| Message ID | 147938970382.13574.11581172952175034619.stgit@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 2016-11-17 at 13:35 +0000, David Howells wrote: > Add a system call to make extended file information available, including > file creation, data version and some attribute flags where available > through the underlying filesystem. > > > ======== > OVERVIEW > ======== > > The idea was initially proposed as a set of xattrs that could be retrieved > with getxattr(), but the general preferance proved to be for a new syscall > with an extended stat structure. > > This has a number of uses: > > (1) Better support for the y2038 problem [Arnd Bergmann]. > > (2) Creation time: The SMB protocol carries the creation time, which could > be exported by Samba, which will in turn help CIFS make use of > FS-Cache as that can be used for coherency data. > > This is also specified in NFSv4 as a recommended attribute and could > be exported by NFSD [Steve French]. > > (3) Lightweight stat: Ask for just those details of interest, and allow a > netfs (such as NFS) to approximate anything not of interest, possibly > without going to the server [Trond Myklebust, Ulrich Drepper, Andreas > Dilger]. > > (4) Heavyweight stat: Force a netfs to go to the server, even if it thinks > its cached attributes are up to date [Trond Myklebust]. > > (5) Data version number: Could be used by userspace NFS servers [Aneesh > Kumar]. > > Can also be used to modify fill_post_wcc() in NFSD which retrieves > i_version directly, but has just called vfs_getattr(). It could get > it from the kstat struct if it used vfs_xgetattr() instead. > > (6) BSD stat compatibility: Including more fields from the BSD stat such > as creation time (st_btime) and inode generation number (st_gen) > [Jeremy Allison, Bernd Schubert]. > > (7) Inode generation number: Useful for FUSE and userspace NFS servers > [Bernd Schubert]. This was asked for but later deemed unnecessary > with the open-by-handle capability available > > (8) Extra coherency data may be useful in making backups [Andreas Dilger]. > > (9) Allow the filesystem to indicate what it can/cannot provide: A > filesystem can now say it doesn't support a standard stat feature if > that isn't available, so if, for instance, inode numbers or UIDs don't > exist or are fabricated locally... > > (10) Make the fields a consistent size on all arches and make them large. > > (11) Store a 16-byte volume ID in the superblock that can be returned in > struct xstat [Steve French]. > > (12) Include granularity fields in the time data to indicate the > granularity of each of the times (NFSv4 time_delta) [Steve French]. > > (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. > Note that the Linux IOC flags are a mess and filesystems such as Ext4 > define flags that aren't in linux/fs.h, so translation in the kernel > may be a necessity (or, possibly, we provide the filesystem type too). > > (14) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer, > Michael Kerrisk]. > > (15) Spare space, request flags and information flags are provided for > future expansion. > > Note that not all of the above are implemented here. > > > =============== > NEW SYSTEM CALL > =============== > > The new system call is: > > int ret = statx(int dfd, > const char *filename, > unsigned int flags, > unsigned int mask, > struct statx *buffer); > > The dfd, filename and flags parameters indicate the file to query. There > is no equivalent of lstat() as that can be emulated with statx() by passing > AT_SYMLINK_NOFOLLOW in flags. There is also no equivalent of fstat() as > that can be emulated by passing a NULL filename to statx() with the fd of > interest in dfd. > > AT_STATX_FORCE_SYNC can be set in flags. This will require a network > filesystem to synchronise its attributes with the server. > > AT_STATX_DONT_SYNC can be set in flags. This will suppress synchronisation > with the server in a network filesystem. The resulting values should be > considered approximate. > > If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for > stat() on that filesystem. > We also need to specify here what happens if both bits are set. Should that be -EINVAL? > mask is a bitmask indicating the fields in struct statx that are of > interest to the caller. The user should set this to STATX_BASIC_STATS to > get the basic set returned by stat(). It should be note that asking for > more information may entail more I/O operations. > > buffer points to the destination for the data. This must be 256 bytes in > size. > > > ====================== > MAIN ATTRIBUTES RECORD > ====================== > > The following structures are defined in which to return the main attribute > set: > > struct statx { > __u32 stx_mask; > __u32 stx_blksize; > __u64 stx_attributes; > __u32 stx_nlink; > __u32 stx_uid; > __u32 stx_gid; > __u16 stx_mode; > __u16 __spare0[1]; > __u64 stx_ino; > __u64 stx_size; > __u64 stx_blocks; > __u64 stx_version; > __s64 stx_atime; > __s64 stx_btime; > __s64 stx_ctime; > __s64 stx_mtime; > __s32 stx_atime_ns; > __s32 stx_btime_ns; > __s32 stx_ctime_ns; > __s32 stx_mtime_ns; > __u32 stx_rdev_major; > __u32 stx_rdev_minor; > __u32 stx_dev_major; > __u32 stx_dev_minor; > __u64 __spare1[16]; > }; > > The defined bits in request_mask and stx_mask are: > > STATX_TYPE Want/got stx_mode & S_IFMT > STATX_MODE Want/got stx_mode & ~S_IFMT > STATX_NLINK Want/got stx_nlink > STATX_UID Want/got stx_uid > STATX_GID Want/got stx_gid > STATX_ATIME Want/got stx_atime{,_ns} > STATX_MTIME Want/got stx_mtime{,_ns} > STATX_CTIME Want/got stx_ctime{,_ns} > STATX_INO Want/got stx_ino > STATX_SIZE Want/got stx_size > STATX_BLOCKS Want/got stx_blocks > STATX_BASIC_STATS [The stuff in the normal stat struct] > STATX_BTIME Want/got stx_btime{,_ns} > STATX_VERSION Want/got stx_version > STATX_ALL [All currently available stuff] > > stx_btime is the file creation time; stx_version is the data version number > (i_version); stx_mask is a bitmask indicating the data provided; and > __spares*[] are where as-yet undefined fields can be placed. > > Time fields are split into separate seconds and nanoseconds fields to make > packing easier and the granularities can be queried with the filesystem > info system call. Note that times will be negative if before 1970; in such > a case, the nanosecond fields will also be negative if not zero. > > The bits defined in the stx_attributes field convey information about a > file, how it is accessed, where it is and what it does. The following > attributes map to FS_*_FL flags and are the same numerical value: > > STATX_ATTR_COMPRESSED File is compressed by the fs > STATX_ATTR_IMMUTABLE File is marked immutable > STATX_ATTR_APPEND File is append-only > STATX_ATTR_NODUMP File is not to be dumped > STATX_ATTR_ENCRYPTED File requires key to decrypt in fs > > The supported flags are listed by: > > STATX_ATTR_FS_IOC_FLAGS > > [Are any other IOC flags of sufficient general interest to be exposed > through this interface?] > > New flags include: > > STATX_ATTR_NONUNIX_OWNERSHIP File doesn't have Unixy ownership > STATX_ATTR_HAS_ACL File has an ACL > STATX_ATTR_KERNEL_API File is kernel API (eg: procfs/sysfs) > STATX_ATTR_REMOTE File is remote and needs network > STATX_ATTR_FABRICATED File was made up by fs > STATX_ATTR_AUTOMOUNT Object is an automount trigger > STATX_ATTR_UNLISTED_DENTS Dir: Lookup may find files getdents doesn't > > These are for the use of GUI tools that might want to mark files specially, > depending on what they are. > > Fields in struct statx come in a number of classes: > > (0) stx_dev_*, stx_blksize. > > These are local system information and are always available. > > (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time*, stx_ino, > stx_size, stx_blocks. > > These will be returned whether the caller asks for them or not. The > corresponding bits in stx_mask will be set to indicate whether they > actually have valid values. > > If the caller didn't ask for them, then they may be approximated. For > example, NFS won't waste any time updating them from the server, > unless as a byproduct of updating something requested. > > If the values don't actually exist for the underlying object (such as > UID or GID on a DOS file), then the bit won't be set in the stx_mask, > even if the caller asked for the value. In such a case, the returned > value will be a fabrication. > > Note that there are instances where the type might not be valid, for > instance Windows reparse points. > > (2) stx_rdev_*. > > This will be set only if stx_mode indicates we're looking at a > blockdev or a chardev, otherwise will be 0. > > (3) stx_btime*, stx_version. > > Similar to (1), except these will be set to 0 if they don't exist. > > > ======= > TESTING > ======= > > The following test program can be used to test the statx system call: > > samples/statx/test-statx.c > > Just compile and run, passing it paths to the files you want to examine. > The file is built automatically if CONFIG_SAMPLES is enabled. > > Here's some example output. Firstly, an NFS directory that crosses to > another FSID. Note that the FABRICATED and AUTOMOUNT info flags are set. > The former because the directory is invented locally as we don't see the > underlying dir on the server, the latter because transiting this directory > will cause d_automount to be invoked by the VFS. > > [root@andromeda tmp]# ./samples/statx/test-statx -A /warthog/data > statx(/warthog/data) = 0 > results=17ff > Size: 4096 Blocks: 8 IO Block: 1048576 directory > Device: 00:26 Inode: 1703937 Links: 124 > Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 > Access: 2016-11-10 15:52:11.219935864+0000 > Modify: 2016-11-10 08:07:32.482314928+0000 > Change: 2016-11-10 08:07:32.482314928+0000 > Data version: 58242ac41cbf8ab0h > Attributes: 000000000000e000 (-------- -------- -------- -------- -------- -------- mfr----- --------) > IO-blocksize: blksize=1048576 > > Secondly, the result of automounting on that directory. > > [root@andromeda tmp]# ./samples/statx/test-statx /warthog/data > statx(/warthog/data) = 0 > results=17ff > Size: 4096 Blocks: 8 IO Block: 1048576 directory > Device: 00:27 Inode: 2 Links: 124 > Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 > Access: 2016-11-10 15:52:11.219935864+0000 > Modify: 2016-11-10 08:07:32.482314928+0000 > Change: 2016-11-10 08:07:32.482314928+0000 > Data version: 58242ac41cbf8ab0h > Attributes: 0000000000002000 (-------- -------- -------- -------- -------- -------- --r----- --------) > IO-blocksize: blksize=1048576 > > Signed-off-by: David Howells <dhowells@redhat.com> > --- > > arch/x86/entry/syscalls/syscall_32.tbl | 1 > arch/x86/entry/syscalls/syscall_64.tbl | 1 > fs/exportfs/expfs.c | 4 > fs/stat.c | 294 +++++++++++++++++++++++++++++--- > include/linux/fs.h | 5 - > include/linux/stat.h | 19 +- > include/linux/syscalls.h | 3 > include/uapi/linux/fcntl.h | 2 > include/uapi/linux/stat.h | 124 +++++++++++++ > samples/Kconfig | 5 + > samples/Makefile | 3 > samples/statx/Makefile | 10 + > samples/statx/test-statx.c | 248 +++++++++++++++++++++++++++ > 13 files changed, 679 insertions(+), 40 deletions(-) > create mode 100644 samples/statx/Makefile > create mode 100644 samples/statx/test-statx.c > > diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl > index 2b3618542544..9ba050fe47f3 100644 > --- a/arch/x86/entry/syscalls/syscall_32.tbl > +++ b/arch/x86/entry/syscalls/syscall_32.tbl > @@ -389,3 +389,4 @@ > 380 i386 pkey_mprotect sys_pkey_mprotect > 381 i386 pkey_alloc sys_pkey_alloc > 382 i386 pkey_free sys_pkey_free > +383 i386 statx sys_statx > diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl > index e93ef0b38db8..5aef183e2f85 100644 > --- a/arch/x86/entry/syscalls/syscall_64.tbl > +++ b/arch/x86/entry/syscalls/syscall_64.tbl > @@ -338,6 +338,7 @@ > 329 common pkey_mprotect sys_pkey_mprotect > 330 common pkey_alloc sys_pkey_alloc > 331 common pkey_free sys_pkey_free > +332 common statx sys_statx > > # > # x32-specific system call numbers start at 512 to avoid cache impact > diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c > index a4b531be9168..2acc31751248 100644 > --- a/fs/exportfs/expfs.c > +++ b/fs/exportfs/expfs.c > @@ -299,7 +299,9 @@ static int get_name(const struct path *path, char *name, struct dentry *child) > * filesystem supports 64-bit inode numbers. So we need to > * actually call ->getattr, not just read i_ino: > */ > - error = vfs_getattr_nosec(&child_path, &stat); > + stat.query_flags = 0; > + stat.request_mask = STATX_BASIC_STATS; > + error = vfs_xgetattr_nosec(&child_path, &stat); > if (error) > return error; > buffer.ino = stat.ino; > diff --git a/fs/stat.c b/fs/stat.c > index bc045c7994e1..78c0a5086038 100644 > --- a/fs/stat.c > +++ b/fs/stat.c > @@ -18,6 +18,15 @@ > #include <asm/uaccess.h> > #include <asm/unistd.h> > > +/** > + * generic_fillattr - Fill in the basic attributes from the inode struct > + * @inode: Inode to use as the source > + * @stat: Where to fill in the attributes > + * > + * Fill in the basic attributes in the kstat structure from data that's to be > + * found on the VFS inode structure. This is the default if no getattr inode > + * operation is supplied. > + */ > void generic_fillattr(struct inode *inode, struct kstat *stat) > { > stat->dev = inode->i_sb->s_dev; > @@ -27,87 +36,189 @@ void generic_fillattr(struct inode *inode, struct kstat *stat) > stat->uid = inode->i_uid; > stat->gid = inode->i_gid; > stat->rdev = inode->i_rdev; > - stat->size = i_size_read(inode); > - stat->atime = inode->i_atime; > stat->mtime = inode->i_mtime; > stat->ctime = inode->i_ctime; > - stat->blksize = (1 << inode->i_blkbits); > + stat->size = i_size_read(inode); > stat->blocks = inode->i_blocks; > -} > + stat->blksize = 1 << inode->i_blkbits; > > + stat->result_mask |= STATX_BASIC_STATS; > + if (IS_NOATIME(inode)) > + stat->result_mask &= ~STATX_ATIME; > + else > + stat->atime = inode->i_atime; > + > + if (IS_AUTOMOUNT(inode)) > + stat->attributes |= STATX_ATTR_AUTOMOUNT; > +} > EXPORT_SYMBOL(generic_fillattr); > > /** > - * vfs_getattr_nosec - getattr without security checks > + * vfs_xgetattr_nosec - getattr without security checks > * @path: file to get attributes from > * @stat: structure to return attributes in > * > * Get attributes without calling security_inode_getattr. > * > - * Currently the only caller other than vfs_getattr is internal to the > - * filehandle lookup code, which uses only the inode number and returns > - * no attributes to any user. Any other code probably wants > - * vfs_getattr. > + * Currently the only caller other than vfs_xgetattr is internal to the > + * filehandle lookup code, which uses only the inode number and returns no > + * attributes to any user. Any other code probably wants vfs_xgetattr. > + * > + * The caller must set stat->request_mask to indicate what they want and > + * stat->query_flags to indicate whether the server should be queried. > */ > -int vfs_getattr_nosec(struct path *path, struct kstat *stat) > +int vfs_xgetattr_nosec(struct path *path, struct kstat *stat) > { > struct inode *inode = d_backing_inode(path->dentry); > > + stat->query_flags &= ~KSTAT_QUERY_FLAGS; > + > + stat->result_mask = 0; > + stat->attributes = 0; > if (inode->i_op->getattr) > return inode->i_op->getattr(path->mnt, path->dentry, stat); > > generic_fillattr(inode, stat); > return 0; > } > +EXPORT_SYMBOL(vfs_xgetattr_nosec); > > -EXPORT_SYMBOL(vfs_getattr_nosec); > - > -int vfs_getattr(struct path *path, struct kstat *stat) > +/* > + * vfs_xgetattr - Get the enhanced basic attributes of a file > + * @path: The file of interest > + * @stat: Where to return the statistics > + * > + * Ask the filesystem for a file's attributes. The caller must have preset > + * stat->request_mask and stat->query_flags to indicate what they want. > + * > + * If the file is remote, the filesystem can be forced to update the attributes > + * from the backing store by passing AT_FORCE_ATTR_SYNC in query_flags or can > + * suppress the update by passing AT_NO_ATTR_SYNC. > + * > + * Bits must have been set in stat->request_mask to indicate which attributes > + * the caller wants retrieving. Any such attribute not requested may be > + * returned anyway, but the value may be approximate, and, if remote, may not > + * have been synchronised with the server. > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > +int vfs_xgetattr(struct path *path, struct kstat *stat) > { > int retval; > > retval = security_inode_getattr(path); > if (retval) > return retval; > - return vfs_getattr_nosec(path, stat); > + return vfs_xgetattr_nosec(path, stat); > } > +EXPORT_SYMBOL(vfs_xgetattr); > > +/** > + * vfs_getattr - Get the basic attributes of a file > + * @path: The file of interest > + * @stat: Where to return the statistics > + * > + * Ask the filesystem for a file's attributes. If remote, the filesystem isn't > + * forced to update its files from the backing store. Only the basic set of > + * attributes will be retrieved; anyone wanting more must use vfs_xgetattr(), > + * as must anyone who wants to force attributes to be sync'd with the server. > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > +int vfs_getattr(struct path *path, struct kstat *stat) > +{ > + stat->query_flags = 0; > + stat->request_mask = STATX_BASIC_STATS; > + return vfs_xgetattr(path, stat); > +} > EXPORT_SYMBOL(vfs_getattr); > > -int vfs_fstat(unsigned int fd, struct kstat *stat) > +/** > + * vfs_fstatx - Get the enhanced basic attributes by file descriptor > + * @fd: The file descriptor referring to the file of interest > + * @stat: The result structure to fill in. > + * > + * This function is a wrapper around vfs_xgetattr(). The main difference is > + * that it uses a file descriptor to determine the file location. > + * > + * The caller must have preset stat->query_flags and stat->request_mask as for > + * vfs_xgetattr(). > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > +int vfs_fstatx(unsigned int fd, struct kstat *stat) > { > struct fd f = fdget_raw(fd); > int error = -EBADF; > > if (f.file) { > - error = vfs_getattr(&f.file->f_path, stat); > + error = vfs_xgetattr(&f.file->f_path, stat); > fdput(f); > } > return error; > } > +EXPORT_SYMBOL(vfs_fstatx); > + > +/** > + * vfs_fstat - Get basic attributes by file descriptor > + * @fd: The file descriptor referring to the file of interest > + * @stat: The result structure to fill in. > + * > + * This function is a wrapper around vfs_getattr(). The main difference is > + * that it uses a file descriptor to determine the file location. > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > +int vfs_fstat(unsigned int fd, struct kstat *stat) > +{ > + stat->query_flags = 0; > + stat->request_mask = STATX_BASIC_STATS; > + return vfs_fstatx(fd, stat); > +} > EXPORT_SYMBOL(vfs_fstat); > > -int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, > - int flag) > +/** > + * vfs_statx - Get basic and extra attributes by filename > + * @dfd: A file descriptor representing the base dir for a relative filename > + * @filename: The name of the file of interest > + * @flags: Flags to control the query > + * @stat: The result structure to fill in. > + * > + * This function is a wrapper around vfs_xgetattr(). The main difference is > + * that it uses a filename and base directory to determine the file location. > + * Additionally, the addition of AT_SYMLINK_NOFOLLOW to flags will prevent a > + * symlink at the given name from being referenced. > + * > + * The caller must have preset stat->request_mask as for vfs_xgetattr(). The > + * flags are also used to load up stat->query_flags. > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > +int vfs_statx(int dfd, const char __user *filename, int flags, > + struct kstat *stat) > { > struct path path; > int error = -EINVAL; > - unsigned int lookup_flags = 0; > + unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT; > > - if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | > - AT_EMPTY_PATH)) != 0) > - goto out; > + if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | > + AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0) > + return -EINVAL; > > - if (!(flag & AT_SYMLINK_NOFOLLOW)) > - lookup_flags |= LOOKUP_FOLLOW; > - if (flag & AT_EMPTY_PATH) > + if (flags & AT_SYMLINK_NOFOLLOW) > + lookup_flags &= ~LOOKUP_FOLLOW; > + if (flags & AT_NO_AUTOMOUNT) > + lookup_flags &= ~LOOKUP_AUTOMOUNT; > + if (flags & AT_EMPTY_PATH) > lookup_flags |= LOOKUP_EMPTY; > + stat->query_flags = flags; > + > retry: > error = user_path_at(dfd, filename, lookup_flags, &path); > if (error) > goto out; > > - error = vfs_getattr(&path, stat); > + error = vfs_xgetattr(&path, stat); > path_put(&path); > if (retry_estale(error, lookup_flags)) { > lookup_flags |= LOOKUP_REVAL; > @@ -116,17 +227,65 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, > out: > return error; > } > +EXPORT_SYMBOL(vfs_statx); > + > +/** > + * vfs_fstatat - Get basic attributes by filename > + * @dfd: A file descriptor representing the base dir for a relative filename > + * @filename: The name of the file of interest > + * @flags: Flags to control the query > + * @stat: The result structure to fill in. > + * > + * This function is a wrapper around vfs_statx(). The difference is that it > + * preselects basic stats only. The flags are used to load up > + * stat->query_flags in addition to indicating symlink handling during path > + * resolution. > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > +int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, > + int flags) > +{ > + stat->request_mask = STATX_BASIC_STATS; > + return vfs_statx(dfd, filename, flags, stat); > +} > EXPORT_SYMBOL(vfs_fstatat); > > -int vfs_stat(const char __user *name, struct kstat *stat) > +/** > + * vfs_stat - Get basic attributes by filename > + * @filename: The name of the file of interest > + * @stat: The result structure to fill in. > + * > + * This function is a wrapper around vfs_statx(). The difference is that it > + * preselects basic stats only, terminal symlinks are followed regardless and a > + * remote filesystem can't be forced to query the server. If such is desired, > + * vfs_statx() should be used instead. > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > +int vfs_stat(const char __user *filename, struct kstat *stat) > { > - return vfs_fstatat(AT_FDCWD, name, stat, 0); > + stat->request_mask = STATX_BASIC_STATS; > + return vfs_statx(AT_FDCWD, filename, 0, stat); > } > EXPORT_SYMBOL(vfs_stat); > > +/** > + * vfs_lstat - Get basic attrs by filename, without following terminal symlink > + * @filename: The name of the file of interest > + * @stat: The result structure to fill in. > + * > + * This function is a wrapper around vfs_statx(). The difference is that it > + * preselects basic stats only, terminal symlinks are note followed regardless > + * and a remote filesystem can't be forced to query the server. If such is > + * desired, vfs_statx() should be used instead. > + * > + * 0 will be returned on success, and a -ve error code if unsuccessful. > + */ > int vfs_lstat(const char __user *name, struct kstat *stat) > { > - return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW); > + stat->request_mask = STATX_BASIC_STATS; > + return vfs_statx(AT_FDCWD, name, AT_SYMLINK_NOFOLLOW, stat); > } > EXPORT_SYMBOL(vfs_lstat); > > @@ -141,7 +300,7 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta > { > static int warncount = 5; > struct __old_kernel_stat tmp; > - > + > if (warncount > 0) { > warncount--; > printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n", > @@ -166,7 +325,7 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta > #if BITS_PER_LONG == 32 > if (stat->size > MAX_NON_LFS) > return -EOVERFLOW; > -#endif > +#endif > tmp.st_size = stat->size; > tmp.st_atime = stat->atime.tv_sec; > tmp.st_mtime = stat->mtime.tv_sec; > @@ -443,6 +602,79 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename, > } > #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */ > > +/* > + * Set the statx results. > + */ > +static long statx_set_result(struct kstat *stat, struct statx __user *buffer) > +{ > + uid_t uid = from_kuid_munged(current_user_ns(), stat->uid); > + gid_t gid = from_kgid_munged(current_user_ns(), stat->gid); > + > +#define __put_timestamp(kts, uts) ( \ > + __put_user(kts.tv_sec, uts##_s ) || \ > + __put_user(kts.tv_nsec, uts##_ns )) > + > + if (__put_user(stat->result_mask, &buffer->stx_mask ) || > + __put_user(stat->mode, &buffer->stx_mode ) || > + __clear_user(&buffer->__spare0, sizeof(buffer->__spare0)) || > + __put_user(stat->nlink, &buffer->stx_nlink ) || > + __put_user(uid, &buffer->stx_uid ) || > + __put_user(gid, &buffer->stx_gid ) || > + __put_user(stat->attributes, &buffer->stx_attributes ) || > + __put_user(stat->blksize, &buffer->stx_blksize ) || > + __put_user(MAJOR(stat->rdev), &buffer->stx_rdev_major ) || > + __put_user(MINOR(stat->rdev), &buffer->stx_rdev_minor ) || > + __put_user(MAJOR(stat->dev), &buffer->stx_dev_major ) || > + __put_user(MINOR(stat->dev), &buffer->stx_dev_minor ) || > + __put_timestamp(stat->atime, &buffer->stx_atime ) || > + __put_timestamp(stat->btime, &buffer->stx_btime ) || > + __put_timestamp(stat->ctime, &buffer->stx_ctime ) || > + __put_timestamp(stat->mtime, &buffer->stx_mtime ) || > + __put_user(stat->ino, &buffer->stx_ino ) || > + __put_user(stat->size, &buffer->stx_size ) || > + __put_user(stat->blocks, &buffer->stx_blocks ) || > + __put_user(stat->version, &buffer->stx_version ) || > + __clear_user(&buffer->__spare1, sizeof(buffer->__spare1))) > + return -EFAULT; > + > + return 0; > +} > + > +/** > + * sys_statx - System call to get enhanced stats > + * @dfd: Base directory to pathwalk from *or* fd to stat. > + * @filename: File to stat *or* NULL. > + * @flags: AT_* flags to control pathwalk. > + * @mask: Parts of statx struct actually required. > + * @buffer: Result buffer. > + * > + * Note that if filename is NULL, then it does the equivalent of fstat() using > + * dfd to indicate the file of interest. > + */ > +SYSCALL_DEFINE5(statx, > + int, dfd, const char __user *, filename, unsigned, flags, > + unsigned int, mask, > + struct statx __user *, buffer) > +{ > + struct kstat stat; > + int error; > + > + if (!access_ok(VERIFY_WRITE, buffer, sizeof(*buffer))) > + return -EFAULT; > + > + memset(&stat, 0, sizeof(stat)); > + stat.query_flags = flags; > + stat.request_mask = mask & STATX_ALL; > + > + if (filename) > + error = vfs_statx(dfd, filename, flags, &stat); > + else > + error = vfs_fstatx(dfd, &stat); > + if (error) > + return error; > + return statx_set_result(&stat, buffer); > +} > + > /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */ > void __inode_add_bytes(struct inode *inode, loff_t bytes) > { > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 16d2b6e874d6..f153199566b4 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2916,8 +2916,9 @@ extern const struct inode_operations page_symlink_inode_operations; > extern void kfree_link(void *); > extern int generic_readlink(struct dentry *, char __user *, int); > extern void generic_fillattr(struct inode *, struct kstat *); > -int vfs_getattr_nosec(struct path *path, struct kstat *stat); > +extern int vfs_xgetattr_nosec(struct path *path, struct kstat *stat); > extern int vfs_getattr(struct path *, struct kstat *); > +extern int vfs_xgetattr(struct path *, struct kstat *); > void __inode_add_bytes(struct inode *inode, loff_t bytes); > void inode_add_bytes(struct inode *inode, loff_t bytes); > void __inode_sub_bytes(struct inode *inode, loff_t bytes); > @@ -2935,6 +2936,8 @@ extern int vfs_lstat(const char __user *, struct kstat *); > extern int vfs_fstat(unsigned int, struct kstat *); > extern int vfs_fstatat(int , const char __user *, struct kstat *, int); > extern const char *vfs_get_link(struct dentry *, struct delayed_call *); > +extern int vfs_xstat(int, const char __user *, int, struct kstat *); > +extern int vfs_xfstat(unsigned int, struct kstat *); > > extern int __generic_block_fiemap(struct inode *inode, > struct fiemap_extent_info *fieinfo, > diff --git a/include/linux/stat.h b/include/linux/stat.h > index 075cb0c7eb2a..cf25bb5cf754 100644 > --- a/include/linux/stat.h > +++ b/include/linux/stat.h > @@ -19,19 +19,26 @@ > #include <linux/uidgid.h> > > struct kstat { > - u64 ino; > - dev_t dev; > + u32 query_flags; /* Operational flags */ > +#define KSTAT_QUERY_FLAGS (AT_STATX_FORCE_SYNC | AT_STATX_DONT_SYNC) > + u32 request_mask; /* What fields the user asked for */ > + u32 result_mask; /* What fields the user got */ > umode_t mode; > unsigned int nlink; > + uint32_t blksize; /* Preferred I/O size */ > + u64 attributes; > + u64 ino; > + dev_t dev; > + dev_t rdev; > kuid_t uid; > kgid_t gid; > - dev_t rdev; > loff_t size; > - struct timespec atime; > + struct timespec atime; > struct timespec mtime; > struct timespec ctime; > - unsigned long blksize; > - unsigned long long blocks; > + struct timespec btime; /* File creation time */ > + u64 blocks; > + u64 version; /* Data version */ > }; > > #endif > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h > index 91a740f6b884..980c3c9b06f8 100644 > --- a/include/linux/syscalls.h > +++ b/include/linux/syscalls.h > @@ -48,6 +48,7 @@ struct stat; > struct stat64; > struct statfs; > struct statfs64; > +struct statx; > struct __sysctl_args; > struct sysinfo; > struct timespec; > @@ -902,5 +903,7 @@ asmlinkage long sys_pkey_mprotect(unsigned long start, size_t len, > unsigned long prot, int pkey); > asmlinkage long sys_pkey_alloc(unsigned long flags, unsigned long init_val); > asmlinkage long sys_pkey_free(int pkey); > +asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags, > + unsigned mask, struct statx __user *buffer); > > #endif > diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h > index beed138bd359..c49cb6edaafa 100644 > --- a/include/uapi/linux/fcntl.h > +++ b/include/uapi/linux/fcntl.h > @@ -62,6 +62,8 @@ > #define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */ > #define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */ > #define AT_EMPTY_PATH 0x1000 /* Allow empty relative pathname */ > +#define AT_STATX_FORCE_SYNC 0x2000 /* Force the attributes to be sync'd with the server */ > +#define AT_STATX_DONT_SYNC 0x4000 /* Don't sync attributes with the server */ > > > #endif /* _UAPI_LINUX_FCNTL_H */ > diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h > index 7fec7e36d921..32ea14c1c960 100644 > --- a/include/uapi/linux/stat.h > +++ b/include/uapi/linux/stat.h > @@ -1,6 +1,7 @@ > #ifndef _UAPI_LINUX_STAT_H > #define _UAPI_LINUX_STAT_H > > +#include <linux/types.h> > > #if defined(__KERNEL__) || !defined(__GLIBC__) || (__GLIBC__ < 2) > > @@ -41,5 +42,128 @@ > > #endif > > +/* > + * Structures for the extended file attribute retrieval system call > + * (statx()). > + * > + * The caller passes a mask of what they're specifically interested in as a > + * parameter to statx(). What statx() actually got will be indicated in > + * st_mask upon return. > + * > + * For each bit in the mask argument: > + * > + * - if the datum is not supported: > + * > + * - the bit will be cleared, and > + * > + * - the datum will be set to an appropriate fabricated value if one is > + * available (eg. CIFS can take a default uid and gid), otherwise > + * > + * - the field will be cleared; > + * > + * - otherwise, if explicitly requested: > + * > + * - the datum will be synchronised to the server if AT_STATX_FORCE_SYNC is > + * set or if the datum is considered out of date, and > + * > + * - the field will be filled in and the bit will be set; > + * > + * - otherwise, if not requested, but available in approximate form without any > + * effort, it will be filled in anyway, and the bit will be set upon return > + * (it might not be up to date, however, and no attempt will be made to > + * synchronise the internal state first); > + * > + * - otherwise the field and the bit will be cleared before returning. > + * > + * Items in STATX_BASIC_STATS may be marked unavailable on return, but they > + * will have values installed for compatibility purposes so that stat() and > + * co. can be emulated in userspace. > + */ > +struct statx { > + /* 0x00 */ > + __u32 stx_mask; /* What results were written [uncond] */ > + __u32 stx_blksize; /* Preferred general I/O size [uncond] */ > + __u64 stx_attributes; /* Flags conveying information about the file [uncond] */ > + /* 0x10 */ > + __u32 stx_nlink; /* Number of hard links */ > + __u32 stx_uid; /* User ID of owner */ > + __u32 stx_gid; /* Group ID of owner */ > + __u16 stx_mode; /* File mode */ > + __u16 __spare0[1]; > + /* 0x20 */ > + __u64 stx_ino; /* Inode number */ > + __u64 stx_size; /* File size */ > + __u64 stx_blocks; /* Number of 512-byte blocks allocated */ > + __u64 stx_version; /* Data version number */ > + /* 0x40 */ > + __s64 stx_atime_s; /* Last access time */ > + __s64 stx_btime_s; /* File creation time */ > + __s64 stx_ctime_s; /* Last attribute change time */ > + __s64 stx_mtime_s; /* Last data modification time */ > + /* 0x60 */ > + __s32 stx_atime_ns; /* Last access time (ns part) */ > + __s32 stx_btime_ns; /* File creation time (ns part) */ > + __s32 stx_ctime_ns; /* Last attribute change time (ns part) */ > + __s32 stx_mtime_ns; /* Last data modification time (ns part) */ > + /* 0x70 */ > + __u32 stx_rdev_major; /* Device ID of special file [if bdev/cdev] */ > + __u32 stx_rdev_minor; > + __u32 stx_dev_major; /* ID of device containing file [uncond] */ > + __u32 stx_dev_minor; > + /* 0x80 */ > + __u64 __spare1[16]; /* Spare space for future expansion */ > + /* 0x100 */ > +}; > + > +/* > + * Flags to be stx_mask > + * > + * Query request/result mask for statx() and struct statx::stx_mask. > + * > + * These bits should be set in the mask argument of statx() to request > + * particular items when calling statx(). > + */ > +#define STATX_TYPE 0x00000001U /* Want/got stx_mode & S_IFMT */ > +#define STATX_MODE 0x00000002U /* Want/got stx_mode & ~S_IFMT */ > +#define STATX_NLINK 0x00000004U /* Want/got stx_nlink */ > +#define STATX_UID 0x00000008U /* Want/got stx_uid */ > +#define STATX_GID 0x00000010U /* Want/got stx_gid */ > +#define STATX_ATIME 0x00000020U /* Want/got stx_atime */ > +#define STATX_MTIME 0x00000040U /* Want/got stx_mtime */ > +#define STATX_CTIME 0x00000080U /* Want/got stx_ctime */ > +#define STATX_INO 0x00000100U /* Want/got stx_ino */ > +#define STATX_SIZE 0x00000200U /* Want/got stx_size */ > +#define STATX_BLOCKS 0x00000400U /* Want/got stx_blocks */ > +#define STATX_BASIC_STATS 0x000007ffU /* The stuff in the normal stat struct */ > +#define STATX_BTIME 0x00000800U /* Want/got stx_btime */ > +#define STATX_VERSION 0x00001000U /* Want/got stx_version */ > +#define STATX_ALL 0x00001fffU /* All currently supported flags */ > + > +/* > + * Attributes to be found in stx_attributes > + * > + * These give information about the features or the state of a file that might > + * be of use to ordinary userspace programs such as GUIs or ls rather than > + * specialised tools. > + * > + * Note that the flags marked [I] correspond to generic FS_IOC_FLAGS > + * semantically. Where possible, the numerical value is picked to correspond > + * also. > + */ > +#define STATX_ATTR_COMPRESSED 0x00000004 /* [I] File is compressed by the fs */ > +#define STATX_ATTR_IMMUTABLE 0x00000010 /* [I] File is marked immutable */ > +#define STATX_ATTR_APPEND 0x00000020 /* [I] File is append-only */ > +#define STATX_ATTR_NODUMP 0x00000040 /* [I] File is not to be dumped */ > +#define STATX_ATTR_NONUNIX_OWNERSHIP 0x00000100 /* File has non-Unix ownership details */ > +#define STATX_ATTR_HAS_ACL 0x00000200 /* File has an ACL */ > +#define STATX_ATTR_ENCRYPTED 0x00000800 /* [I] File requires key to decrypt in fs */ > +#define STATX_ATTR_FS_IOC_FLAGS 0x00000874 /* Attrs corresponding to FS_*_FL flags */ > + > +#define STATX_ATTR_KERNEL_API 0x00001000 /* File is kernel API (eg: procfs/sysfs) */ > +#define STATX_ATTR_REMOTE 0x00002000 /* File is remote and needs network */ > +#define STATX_ATTR_FABRICATED 0x00004000 /* File was made up by fs and is transient */ > +#define STATX_ATTR_AUTOMOUNT 0x00008000 /* Dir: Automount trigger */ > +#define STATX_ATTR_UNLISTED_DENTS 0x00010000 /* Dir: Lookup may find files getdents doesn't */ > + > > #endif /* _UAPI_LINUX_STAT_H */ > diff --git a/samples/Kconfig b/samples/Kconfig > index a6d2a43bbf2e..94a7488f14ae 100644 > --- a/samples/Kconfig > +++ b/samples/Kconfig > @@ -105,4 +105,9 @@ config SAMPLE_BLACKFIN_GPTIMERS > help > Build samples of blackfin gptimers sample module. > > +config SAMPLE_STATX > + bool "Build example extended-stat using code" > + help > + Build example userspace program to use the new extended-stat syscall. > + > endif # SAMPLES > diff --git a/samples/Makefile b/samples/Makefile > index e17d66d77f09..8eeb15e13413 100644 > --- a/samples/Makefile > +++ b/samples/Makefile > @@ -2,4 +2,5 @@ > > obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \ > hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \ > - configfs/ connector/ v4l/ trace_printk/ blackfin/ > + configfs/ connector/ v4l/ trace_printk/ blackfin/ \ > + statx/ > diff --git a/samples/statx/Makefile b/samples/statx/Makefile > new file mode 100644 > index 000000000000..1f80a3d8cf45 > --- /dev/null > +++ b/samples/statx/Makefile > @@ -0,0 +1,10 @@ > +# kbuild trick to avoid linker error. Can be omitted if a module is built. > +obj- := dummy.o > + > +# List of programs to build > +hostprogs-$(CONFIG_SAMPLE_STATX) := test-statx > + > +# Tell kbuild to always build the programs > +always := $(hostprogs-y) > + > +HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include > diff --git a/samples/statx/test-statx.c b/samples/statx/test-statx.c > new file mode 100644 > index 000000000000..2419b33fc15d > --- /dev/null > +++ b/samples/statx/test-statx.c > @@ -0,0 +1,248 @@ > +/* Test the statx() system call > + * > + * Copyright (C) 2015 Red Hat, Inc. All Rights Reserved. > + * Written by David Howells (dhowells@redhat.com) > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public Licence > + * as published by the Free Software Foundation; either version > + * 2 of the Licence, or (at your option) any later version. > + */ > + > +#define _GNU_SOURCE > +#define _ATFILE_SOURCE > +#include <stdio.h> > +#include <stdlib.h> > +#include <string.h> > +#include <unistd.h> > +#include <ctype.h> > +#include <errno.h> > +#include <time.h> > +#include <sys/syscall.h> > +#include <sys/types.h> > +#include <linux/stat.h> > +#include <linux/fcntl.h> > +#include <sys/stat.h> > + > +#define AT_STATX_FORCE_SYNC 0x2000 > +#define AT_STATX_DONT_SYNC 0x4000 > + > +static __attribute__((unused)) > +ssize_t statx(int dfd, const char *filename, unsigned flags, > + unsigned int mask, struct statx *buffer) > +{ > + return syscall(__NR_statx, dfd, filename, flags, mask, buffer); > +} > + > +static void print_time(const char *field, __s64 tv_sec, __s32 tv_nsec) > +{ > + struct tm tm; > + time_t tim; > + char buffer[100]; > + int len; > + > + tim = tv_sec; > + if (!localtime_r(&tim, &tm)) { > + perror("localtime_r"); > + exit(1); > + } > + len = strftime(buffer, 100, "%F %T", &tm); > + if (len == 0) { > + perror("strftime"); > + exit(1); > + } > + printf("%s", field); > + fwrite(buffer, 1, len, stdout); > + printf(".%09u", tv_nsec); > + len = strftime(buffer, 100, "%z", &tm); > + if (len == 0) { > + perror("strftime2"); > + exit(1); > + } > + fwrite(buffer, 1, len, stdout); > + printf("\n"); > +} > + > +static void dump_statx(struct statx *stx) > +{ > + char buffer[256], ft = '?'; > + > + printf("results=%x\n", stx->stx_mask); > + > + printf(" "); > + if (stx->stx_mask & STATX_SIZE) > + printf(" Size: %-15llu", (unsigned long long)stx->stx_size); > + if (stx->stx_mask & STATX_BLOCKS) > + printf(" Blocks: %-10llu", (unsigned long long)stx->stx_blocks); > + printf(" IO Block: %-6llu ", (unsigned long long)stx->stx_blksize); > + if (stx->stx_mask & STATX_MODE) { > + switch (stx->stx_mode & S_IFMT) { > + case S_IFIFO: printf(" FIFO\n"); ft = 'p'; break; > + case S_IFCHR: printf(" character special file\n"); ft = 'c'; break; > + case S_IFDIR: printf(" directory\n"); ft = 'd'; break; > + case S_IFBLK: printf(" block special file\n"); ft = 'b'; break; > + case S_IFREG: printf(" regular file\n"); ft = '-'; break; > + case S_IFLNK: printf(" symbolic link\n"); ft = 'l'; break; > + case S_IFSOCK: printf(" socket\n"); ft = 's'; break; > + default: > + printf("unknown type (%o)\n", stx->stx_mode & S_IFMT); > + break; > + } > + } > + > + sprintf(buffer, "%02x:%02x", stx->stx_dev_major, stx->stx_dev_minor); > + printf("Device: %-15s", buffer); > + if (stx->stx_mask & STATX_INO) > + printf(" Inode: %-11llu", (unsigned long long) stx->stx_ino); > + if (stx->stx_mask & STATX_SIZE) > + printf(" Links: %-5u", stx->stx_nlink); > + switch (stx->stx_mask & STATX_MODE) { > + case S_IFBLK: > + case S_IFCHR: > + printf(" Device type: %u,%u", stx->stx_rdev_major, stx->stx_rdev_minor); > + break; > + } > + printf("\n"); > + > + if (stx->stx_mask & STATX_MODE) > + printf("Access: (%04o/%c%c%c%c%c%c%c%c%c%c) ", > + stx->stx_mode & 07777, > + ft, > + stx->stx_mode & S_IRUSR ? 'r' : '-', > + stx->stx_mode & S_IWUSR ? 'w' : '-', > + stx->stx_mode & S_IXUSR ? 'x' : '-', > + stx->stx_mode & S_IRGRP ? 'r' : '-', > + stx->stx_mode & S_IWGRP ? 'w' : '-', > + stx->stx_mode & S_IXGRP ? 'x' : '-', > + stx->stx_mode & S_IROTH ? 'r' : '-', > + stx->stx_mode & S_IWOTH ? 'w' : '-', > + stx->stx_mode & S_IXOTH ? 'x' : '-'); > + if (stx->stx_mask & STATX_UID) > + printf("Uid: %5d ", stx->stx_uid); > + if (stx->stx_mask & STATX_GID) > + printf("Gid: %5d\n", stx->stx_gid); > + > + if (stx->stx_mask & STATX_ATIME) > + print_time("Access: ", stx->stx_atime_s, stx->stx_atime_ns); > + if (stx->stx_mask & STATX_MTIME) > + print_time("Modify: ", stx->stx_mtime_s, stx->stx_mtime_ns); > + if (stx->stx_mask & STATX_CTIME) > + print_time("Change: ", stx->stx_ctime_s, stx->stx_ctime_ns); > + if (stx->stx_mask & STATX_BTIME) > + print_time(" Birth: ", stx->stx_btime_s, stx->stx_btime_ns); > + > + if (stx->stx_mask & STATX_VERSION) > + printf("Data version: %llxh\n", > + (unsigned long long)stx->stx_version); > + > + if (stx->stx_attributes) { > + unsigned char bits; > + int loop, byte; > + > + static char attr_representation[64 + 1] = > + /* STATX_ATTR_ flags: */ > + "????????" /* 63-56 */ > + "????????" /* 55-48 */ > + "????????" /* 47-40 */ > + "????????" /* 39-32 */ > + "????????" /* 31-24 0x00000000-ff000000 */ > + "???????u" /* 23-16 0x00000000-00ff0000 */ > + "mfrke?AU" /* 15- 8 0x00000000-0000ff00 */ > + "?dai?c??" /* 7- 0 0x00000000-000000ff */ > + ; > + > + printf("Attributes: %016llx (", stx->stx_attributes); > + for (byte = 64 - 8; byte >= 0; byte -= 8) { > + bits = stx->stx_attributes >> byte; > + for (loop = 7; loop >= 0; loop--) { > + int bit = byte + loop; > + > + if (bits & 0x80) > + putchar(attr_representation[63 - bit]); > + else > + putchar('-'); > + bits <<= 1; > + } > + if (byte) > + putchar(' '); > + } > + printf(")\n"); > + } > + > + printf("IO-blocksize: blksize=%u\n", stx->stx_blksize); > +} > + > +static void dump_hex(unsigned long long *data, int from, int to) > +{ > + unsigned offset, print_offset = 1, col = 0; > + > + from /= 8; > + to = (to + 7) / 8; > + > + for (offset = from; offset < to; offset++) { > + if (print_offset) { > + printf("%04x: ", offset * 8); > + print_offset = 0; > + } > + printf("%016llx", data[offset]); > + col++; > + if ((col & 3) == 0) { > + printf("\n"); > + print_offset = 1; > + } else { > + printf(" "); > + } > + } > + > + if (!print_offset) > + printf("\n"); > +} > + > +int main(int argc, char **argv) > +{ > + struct statx stx; > + int ret, raw = 0, atflag = AT_SYMLINK_NOFOLLOW; > + > + unsigned int mask = STATX_ALL; > + > + for (argv++; *argv; argv++) { > + if (strcmp(*argv, "-F") == 0) { > + atflag |= AT_STATX_FORCE_SYNC; > + continue; > + } > + if (strcmp(*argv, "-D") == 0) { > + atflag |= AT_STATX_DONT_SYNC; > + continue; > + } > + if (strcmp(*argv, "-L") == 0) { > + atflag &= ~AT_SYMLINK_NOFOLLOW; > + continue; > + } > + if (strcmp(*argv, "-O") == 0) { > + mask &= ~STATX_BASIC_STATS; > + continue; > + } > + if (strcmp(*argv, "-A") == 0) { > + atflag |= AT_NO_AUTOMOUNT; > + continue; > + } > + if (strcmp(*argv, "-R") == 0) { > + raw = 1; > + continue; > + } > + > + memset(&stx, 0xbf, sizeof(stx)); > + ret = statx(AT_FDCWD, *argv, atflag, mask, &stx); > + printf("statx(%s) = %d\n", *argv, ret); > + if (ret < 0) { > + perror(*argv); > + exit(1); > + } > + > + if (raw) > + dump_hex((unsigned long long *)&stx, 0, sizeof(stx)); > + > + dump_statx(&stx); > + } > + return 0; > +} > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Nov 17, 2016 at 01:35:03PM +0000, David Howells wrote: > Add a system call to make extended file information available, including > file creation, data version and some attribute flags where available > through the underlying filesystem. > > > ======== > OVERVIEW > ======== > > The idea was initially proposed as a set of xattrs that could be retrieved > with getxattr(), but the general preferance proved to be for a new syscall > with an extended stat structure. > > This has a number of uses: > .... > (5) Data version number: Could be used by userspace NFS servers [Aneesh > Kumar]. > > Can also be used to modify fill_post_wcc() in NFSD which retrieves > i_version directly, but has just called vfs_getattr(). It could get > it from the kstat struct if it used vfs_xgetattr() instead. This needs a much clearer name that stx_version as "version" is entirely ambiguous. e.g. Inodes have internal version numbers to disambiguate life cycles. and there are versioning filesystems which have multiple versions of the same file. So if stx_version this is intended to export the internal filesystem inode change counter (i.e. inode->i_version) then lets call it that: stx_modification_count. It's clear and unambiguous as to what it represents, especially as this counter is more than just a "data modification" counter - inode metadata modifications will also cause it to change.... .... > (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. > Note that the Linux IOC flags are a mess and filesystems such as Ext4 > define flags that aren't in linux/fs.h, so translation in the kernel > may be a necessity (or, possibly, we provide the filesystem type too). And we now also have FS_IOC_FSGETXATTR that extends the flags and information userspace can get from filesystems. It makes little sense to now add xstat() and not add everything this interface also exports... > The defined bits in request_mask and stx_mask are: > > STATX_TYPE Want/got stx_mode & S_IFMT > STATX_MODE Want/got stx_mode & ~S_IFMT > STATX_NLINK Want/got stx_nlink > STATX_UID Want/got stx_uid > STATX_GID Want/got stx_gid > STATX_ATIME Want/got stx_atime{,_ns} > STATX_MTIME Want/got stx_mtime{,_ns} > STATX_CTIME Want/got stx_ctime{,_ns} > STATX_INO Want/got stx_ino > STATX_SIZE Want/got stx_size > STATX_BLOCKS Want/got stx_blocks > STATX_BASIC_STATS [The stuff in the normal stat struct] > STATX_BTIME Want/got stx_btime{,_ns} > STATX_VERSION Want/got stx_version > STATX_ALL [All currently available stuff] What happens when an application uses STATX_ALL from a future kernel that defines more flags than are initially supported, and that application then is run on a kernel that onyl supports the initial fields? > stx_btime is the file creation time; stx_version is the data version number > (i_version); stx_mask is a bitmask indicating the data provided; and > __spares*[] are where as-yet undefined fields can be placed. > > Time fields are split into separate seconds and nanoseconds fields to make > packing easier and the granularities can be queried with the filesystem > info system call. Note that times will be negative if before 1970; in such > a case, the nanosecond fields will also be negative if not zero. So what happens in ten years time when we want to support femptosecond resolution in the timestamp interface? We've got to change everything to 64 bit? Shouldn't we just make everything timestamp related 64 bit? > > The bits defined in the stx_attributes field convey information about a > file, how it is accessed, where it is and what it does. The following > attributes map to FS_*_FL flags and are the same numerical value: Please isolate the new interface flags completely from the FS_*_FL values. We should not repeat the mistake of tying values derived from filesystem specific on-disk values to a user interface. > STATX_ATTR_COMPRESSED File is compressed by the fs > STATX_ATTR_IMMUTABLE File is marked immutable > STATX_ATTR_APPEND File is append-only > STATX_ATTR_NODUMP File is not to be dumped > STATX_ATTR_ENCRYPTED File requires key to decrypt in fs > > The supported flags are listed by: > > STATX_ATTR_FS_IOC_FLAGS Again, we have many more common and extended flags than this. NOATIME and SYNC are two that immediately come to mind as generic flags that should be in this... > > [Are any other IOC flags of sufficient general interest to be exposed > through this interface?] > > New flags include: > > STATX_ATTR_NONUNIX_OWNERSHIP File doesn't have Unixy ownership > STATX_ATTR_HAS_ACL File has an ACL So statx will require us to do ACL lookups? i.e. instead of just reading the inode to get the information, we'll also have to do extended attribute lookups? That's potentially very expensive if the extended attribute is not stored in the inode.... > STATX_ATTR_KERNEL_API File is kernel API (eg: procfs/sysfs) > STATX_ATTR_REMOTE File is remote and needs network > STATX_ATTR_FABRICATED File was made up by fs Every file is fabricated by a filesystem :P Perhaps you're wanting "virtual file" because it is has no physical presence? > Fields in struct statx come in a number of classes: > > (0) stx_dev_*, stx_blksize. > > These are local system information and are always available. What does stx_blksize actually mean? It's completely ambiguous in stat() because we don't actually report the physical block size here - we report the "minimum unit of efficient IO" that we expect applications to use. Please define :P > ======= > TESTING > ======= > > The following test program can be used to test the statx system call: > > samples/statx/test-statx.c > > Just compile and run, passing it paths to the files you want to examine. > The file is built automatically if CONFIG_SAMPLES is enabled. Can we get xfstests written to exercise and validate all this functionality, please? I'd suggest that adding xfs_io support for the statx syscall would be far more useful for xfstests than a standalone test program, too. We already have equivalent stat() functionality in xfs_io and that's used quite a bit in xfstests.... Cheers, Dave.
> On Nov 17, 2016, at 11:39 AM, Jeff Layton <jlayton@redhat.com> wrote: > > On Thu, 2016-11-17 at 13:35 +0000, David Howells wrote: >> Add a system call to make extended file information available, including >> file creation, data version and some attribute flags where available >> through the underlying filesystem. >> >> >> ======== >> OVERVIEW >> ======== >> >> The idea was initially proposed as a set of xattrs that could be retrieved >> with getxattr(), but the general preferance proved to be for a new syscall >> with an extended stat structure. >> >> This has a number of uses: >> >> (1) Better support for the y2038 problem [Arnd Bergmann]. >> >> (2) Creation time: The SMB protocol carries the creation time, which could >> be exported by Samba, which will in turn help CIFS make use of >> FS-Cache as that can be used for coherency data. >> >> This is also specified in NFSv4 as a recommended attribute and could >> be exported by NFSD [Steve French]. >> >> (3) Lightweight stat: Ask for just those details of interest, and allow a >> netfs (such as NFS) to approximate anything not of interest, possibly >> without going to the server [Trond Myklebust, Ulrich Drepper, Andreas >> Dilger]. >> >> (4) Heavyweight stat: Force a netfs to go to the server, even if it thinks >> its cached attributes are up to date [Trond Myklebust]. >> >> (5) Data version number: Could be used by userspace NFS servers [Aneesh >> Kumar]. >> >> Can also be used to modify fill_post_wcc() in NFSD which retrieves >> i_version directly, but has just called vfs_getattr(). It could get >> it from the kstat struct if it used vfs_xgetattr() instead. >> >> (6) BSD stat compatibility: Including more fields from the BSD stat such >> as creation time (st_btime) and inode generation number (st_gen) >> [Jeremy Allison, Bernd Schubert]. >> >> (7) Inode generation number: Useful for FUSE and userspace NFS servers >> [Bernd Schubert]. This was asked for but later deemed unnecessary >> with the open-by-handle capability available >> >> (8) Extra coherency data may be useful in making backups [Andreas Dilger]. >> >> (9) Allow the filesystem to indicate what it can/cannot provide: A >> filesystem can now say it doesn't support a standard stat feature if >> that isn't available, so if, for instance, inode numbers or UIDs don't >> exist or are fabricated locally... >> >> (10) Make the fields a consistent size on all arches and make them large. >> >> (11) Store a 16-byte volume ID in the superblock that can be returned in >> struct xstat [Steve French]. >> >> (12) Include granularity fields in the time data to indicate the >> granularity of each of the times (NFSv4 time_delta) [Steve French]. >> >> (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. >> Note that the Linux IOC flags are a mess and filesystems such as Ext4 >> define flags that aren't in linux/fs.h, so translation in the kernel >> may be a necessity (or, possibly, we provide the filesystem type too). >> >> (14) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer, >> Michael Kerrisk]. >> >> (15) Spare space, request flags and information flags are provided for >> future expansion. >> >> Note that not all of the above are implemented here. >> >> >> =============== >> NEW SYSTEM CALL >> =============== >> >> The new system call is: >> >> int ret = statx(int dfd, >> const char *filename, >> unsigned int flags, >> unsigned int mask, >> struct statx *buffer); >> >> The dfd, filename and flags parameters indicate the file to query. There >> is no equivalent of lstat() as that can be emulated with statx() by passing >> AT_SYMLINK_NOFOLLOW in flags. There is also no equivalent of fstat() as >> that can be emulated by passing a NULL filename to statx() with the fd of >> interest in dfd. >> >> AT_STATX_FORCE_SYNC can be set in flags. This will require a network >> filesystem to synchronise its attributes with the server. >> >> AT_STATX_DONT_SYNC can be set in flags. This will suppress synchronisation >> with the server in a network filesystem. The resulting values should be >> considered approximate. >> >> If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for >> stat() on that filesystem. >> > > We also need to specify here what happens if both bits are set. Should > that be -EINVAL? If that is the case, then it doesn't make sense to have two contradictory flags. Pick a default behaviour (i.e. return what is known on the client), and if this is 100% accurate (e.g. local filesystem or filesystem with strong coherency) then it can optionally set the SYNC flag in the returned flags. If the application needs 100% accurate size info, then it can set the SYNC flag in the request and the filesystem may need to do extra work to fetch accurate data from the server. >> mask is a bitmask indicating the fields in struct statx that are of >> interest to the caller. The user should set this to STATX_BASIC_STATS to >> get the basic set returned by stat(). It should be note that asking for >> more information may entail more I/O operations. >> >> buffer points to the destination for the data. This must be 256 bytes in >> size. >> >> >> ====================== >> MAIN ATTRIBUTES RECORD >> ====================== >> >> The following structures are defined in which to return the main attribute >> set: >> >> struct statx { >> __u32 stx_mask; >> __u32 stx_blksize; >> __u64 stx_attributes; >> __u32 stx_nlink; >> __u32 stx_uid; >> __u32 stx_gid; >> __u16 stx_mode; >> __u16 __spare0[1]; >> __u64 stx_ino; >> __u64 stx_size; >> __u64 stx_blocks; >> __u64 stx_version; >> __s64 stx_atime; >> __s64 stx_btime; >> __s64 stx_ctime; >> __s64 stx_mtime; >> __s32 stx_atime_ns; >> __s32 stx_btime_ns; >> __s32 stx_ctime_ns; >> __s32 stx_mtime_ns; >> __u32 stx_rdev_major; >> __u32 stx_rdev_minor; >> __u32 stx_dev_major; >> __u32 stx_dev_minor; >> __u64 __spare1[16]; >> }; >> >> The defined bits in request_mask and stx_mask are: >> >> STATX_TYPE Want/got stx_mode & S_IFMT >> STATX_MODE Want/got stx_mode & ~S_IFMT >> STATX_NLINK Want/got stx_nlink >> STATX_UID Want/got stx_uid >> STATX_GID Want/got stx_gid >> STATX_ATIME Want/got stx_atime{,_ns} >> STATX_MTIME Want/got stx_mtime{,_ns} >> STATX_CTIME Want/got stx_ctime{,_ns} >> STATX_INO Want/got stx_ino >> STATX_SIZE Want/got stx_size >> STATX_BLOCKS Want/got stx_blocks >> STATX_BASIC_STATS [The stuff in the normal stat struct] >> STATX_BTIME Want/got stx_btime{,_ns} >> STATX_VERSION Want/got stx_version >> STATX_ALL [All currently available stuff] >> >> stx_btime is the file creation time; stx_version is the data version number >> (i_version); stx_mask is a bitmask indicating the data provided; and >> __spares*[] are where as-yet undefined fields can be placed. >> >> Time fields are split into separate seconds and nanoseconds fields to make >> packing easier and the granularities can be queried with the filesystem >> info system call. Note that times will be negative if before 1970; in such >> a case, the nanosecond fields will also be negative if not zero. >> >> The bits defined in the stx_attributes field convey information about a >> file, how it is accessed, where it is and what it does. The following >> attributes map to FS_*_FL flags and are the same numerical value: >> >> STATX_ATTR_COMPRESSED File is compressed by the fs >> STATX_ATTR_IMMUTABLE File is marked immutable >> STATX_ATTR_APPEND File is append-only >> STATX_ATTR_NODUMP File is not to be dumped >> STATX_ATTR_ENCRYPTED File requires key to decrypt in fs >> >> The supported flags are listed by: >> >> STATX_ATTR_FS_IOC_FLAGS >> >> [Are any other IOC flags of sufficient general interest to be exposed >> through this interface?] >> >> New flags include: >> >> STATX_ATTR_NONUNIX_OWNERSHIP File doesn't have Unixy ownership >> STATX_ATTR_HAS_ACL File has an ACL >> STATX_ATTR_KERNEL_API File is kernel API (eg: procfs/sysfs) >> STATX_ATTR_REMOTE File is remote and needs network >> STATX_ATTR_FABRICATED File was made up by fs >> STATX_ATTR_AUTOMOUNT Object is an automount trigger >> STATX_ATTR_UNLISTED_DENTS Dir: Lookup may find files getdents doesn't >> >> These are for the use of GUI tools that might want to mark files specially, >> depending on what they are. >> >> Fields in struct statx come in a number of classes: >> >> (0) stx_dev_*, stx_blksize. >> >> These are local system information and are always available. >> >> (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time*, stx_ino, >> stx_size, stx_blocks. >> >> These will be returned whether the caller asks for them or not. The >> corresponding bits in stx_mask will be set to indicate whether they >> actually have valid values. >> >> If the caller didn't ask for them, then they may be approximated. For >> example, NFS won't waste any time updating them from the server, >> unless as a byproduct of updating something requested. >> >> If the values don't actually exist for the underlying object (such as >> UID or GID on a DOS file), then the bit won't be set in the stx_mask, >> even if the caller asked for the value. In such a case, the returned >> value will be a fabrication. >> >> Note that there are instances where the type might not be valid, for >> instance Windows reparse points. >> >> (2) stx_rdev_*. >> >> This will be set only if stx_mode indicates we're looking at a >> blockdev or a chardev, otherwise will be 0. >> >> (3) stx_btime*, stx_version. >> >> Similar to (1), except these will be set to 0 if they don't exist. >> >> >> ======= >> TESTING >> ======= >> >> The following test program can be used to test the statx system call: >> >> samples/statx/test-statx.c >> >> Just compile and run, passing it paths to the files you want to examine. >> The file is built automatically if CONFIG_SAMPLES is enabled. >> >> Here's some example output. Firstly, an NFS directory that crosses to >> another FSID. Note that the FABRICATED and AUTOMOUNT info flags are set. >> The former because the directory is invented locally as we don't see the >> underlying dir on the server, the latter because transiting this directory >> will cause d_automount to be invoked by the VFS. >> >> [root@andromeda tmp]# ./samples/statx/test-statx -A /warthog/data >> statx(/warthog/data) = 0 >> results=17ff >> Size: 4096 Blocks: 8 IO Block: 1048576 directory >> Device: 00:26 Inode: 1703937 Links: 124 >> Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 >> Access: 2016-11-10 15:52:11.219935864+0000 >> Modify: 2016-11-10 08:07:32.482314928+0000 >> Change: 2016-11-10 08:07:32.482314928+0000 >> Data version: 58242ac41cbf8ab0h >> Attributes: 000000000000e000 (-------- -------- -------- -------- -------- -------- mfr----- --------) >> IO-blocksize: blksize=1048576 >> >> Secondly, the result of automounting on that directory. >> >> [root@andromeda tmp]# ./samples/statx/test-statx /warthog/data >> statx(/warthog/data) = 0 >> results=17ff >> Size: 4096 Blocks: 8 IO Block: 1048576 directory >> Device: 00:27 Inode: 2 Links: 124 >> Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 >> Access: 2016-11-10 15:52:11.219935864+0000 >> Modify: 2016-11-10 08:07:32.482314928+0000 >> Change: 2016-11-10 08:07:32.482314928+0000 >> Data version: 58242ac41cbf8ab0h >> Attributes: 0000000000002000 (-------- -------- -------- -------- -------- -------- --r----- --------) >> IO-blocksize: blksize=1048576 >> >> Signed-off-by: David Howells <dhowells@redhat.com> >> --- >> >> arch/x86/entry/syscalls/syscall_32.tbl | 1 >> arch/x86/entry/syscalls/syscall_64.tbl | 1 >> fs/exportfs/expfs.c | 4 >> fs/stat.c | 294 +++++++++++++++++++++++++++++--- >> include/linux/fs.h | 5 - >> include/linux/stat.h | 19 +- >> include/linux/syscalls.h | 3 >> include/uapi/linux/fcntl.h | 2 >> include/uapi/linux/stat.h | 124 +++++++++++++ >> samples/Kconfig | 5 + >> samples/Makefile | 3 >> samples/statx/Makefile | 10 + >> samples/statx/test-statx.c | 248 +++++++++++++++++++++++++++ >> 13 files changed, 679 insertions(+), 40 deletions(-) >> create mode 100644 samples/statx/Makefile >> create mode 100644 samples/statx/test-statx.c >> >> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl >> index 2b3618542544..9ba050fe47f3 100644 >> --- a/arch/x86/entry/syscalls/syscall_32.tbl >> +++ b/arch/x86/entry/syscalls/syscall_32.tbl >> @@ -389,3 +389,4 @@ >> 380 i386 pkey_mprotect sys_pkey_mprotect >> 381 i386 pkey_alloc sys_pkey_alloc >> 382 i386 pkey_free sys_pkey_free >> +383 i386 statx sys_statx >> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl >> index e93ef0b38db8..5aef183e2f85 100644 >> --- a/arch/x86/entry/syscalls/syscall_64.tbl >> +++ b/arch/x86/entry/syscalls/syscall_64.tbl >> @@ -338,6 +338,7 @@ >> 329 common pkey_mprotect sys_pkey_mprotect >> 330 common pkey_alloc sys_pkey_alloc >> 331 common pkey_free sys_pkey_free >> +332 common statx sys_statx >> >> # >> # x32-specific system call numbers start at 512 to avoid cache impact >> diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c >> index a4b531be9168..2acc31751248 100644 >> --- a/fs/exportfs/expfs.c >> +++ b/fs/exportfs/expfs.c >> @@ -299,7 +299,9 @@ static int get_name(const struct path *path, char *name, struct dentry *child) >> * filesystem supports 64-bit inode numbers. So we need to >> * actually call ->getattr, not just read i_ino: >> */ >> - error = vfs_getattr_nosec(&child_path, &stat); >> + stat.query_flags = 0; >> + stat.request_mask = STATX_BASIC_STATS; >> + error = vfs_xgetattr_nosec(&child_path, &stat); >> if (error) >> return error; >> buffer.ino = stat.ino; >> diff --git a/fs/stat.c b/fs/stat.c >> index bc045c7994e1..78c0a5086038 100644 >> --- a/fs/stat.c >> +++ b/fs/stat.c >> @@ -18,6 +18,15 @@ >> #include <asm/uaccess.h> >> #include <asm/unistd.h> >> >> +/** >> + * generic_fillattr - Fill in the basic attributes from the inode struct >> + * @inode: Inode to use as the source >> + * @stat: Where to fill in the attributes >> + * >> + * Fill in the basic attributes in the kstat structure from data that's to be >> + * found on the VFS inode structure. This is the default if no getattr inode >> + * operation is supplied. >> + */ >> void generic_fillattr(struct inode *inode, struct kstat *stat) >> { >> stat->dev = inode->i_sb->s_dev; >> @@ -27,87 +36,189 @@ void generic_fillattr(struct inode *inode, struct kstat *stat) >> stat->uid = inode->i_uid; >> stat->gid = inode->i_gid; >> stat->rdev = inode->i_rdev; >> - stat->size = i_size_read(inode); >> - stat->atime = inode->i_atime; >> stat->mtime = inode->i_mtime; >> stat->ctime = inode->i_ctime; >> - stat->blksize = (1 << inode->i_blkbits); >> + stat->size = i_size_read(inode); >> stat->blocks = inode->i_blocks; >> -} >> + stat->blksize = 1 << inode->i_blkbits; >> >> + stat->result_mask |= STATX_BASIC_STATS; >> + if (IS_NOATIME(inode)) >> + stat->result_mask &= ~STATX_ATIME; >> + else >> + stat->atime = inode->i_atime; >> + >> + if (IS_AUTOMOUNT(inode)) >> + stat->attributes |= STATX_ATTR_AUTOMOUNT; >> +} >> EXPORT_SYMBOL(generic_fillattr); >> >> /** >> - * vfs_getattr_nosec - getattr without security checks >> + * vfs_xgetattr_nosec - getattr without security checks >> * @path: file to get attributes from >> * @stat: structure to return attributes in >> * >> * Get attributes without calling security_inode_getattr. >> * >> - * Currently the only caller other than vfs_getattr is internal to the >> - * filehandle lookup code, which uses only the inode number and returns >> - * no attributes to any user. Any other code probably wants >> - * vfs_getattr. >> + * Currently the only caller other than vfs_xgetattr is internal to the >> + * filehandle lookup code, which uses only the inode number and returns no >> + * attributes to any user. Any other code probably wants vfs_xgetattr. >> + * >> + * The caller must set stat->request_mask to indicate what they want and >> + * stat->query_flags to indicate whether the server should be queried. >> */ >> -int vfs_getattr_nosec(struct path *path, struct kstat *stat) >> +int vfs_xgetattr_nosec(struct path *path, struct kstat *stat) >> { >> struct inode *inode = d_backing_inode(path->dentry); >> >> + stat->query_flags &= ~KSTAT_QUERY_FLAGS; >> + >> + stat->result_mask = 0; >> + stat->attributes = 0; >> if (inode->i_op->getattr) >> return inode->i_op->getattr(path->mnt, path->dentry, stat); >> >> generic_fillattr(inode, stat); >> return 0; >> } >> +EXPORT_SYMBOL(vfs_xgetattr_nosec); >> >> -EXPORT_SYMBOL(vfs_getattr_nosec); >> - >> -int vfs_getattr(struct path *path, struct kstat *stat) >> +/* >> + * vfs_xgetattr - Get the enhanced basic attributes of a file >> + * @path: The file of interest >> + * @stat: Where to return the statistics >> + * >> + * Ask the filesystem for a file's attributes. The caller must have preset >> + * stat->request_mask and stat->query_flags to indicate what they want. >> + * >> + * If the file is remote, the filesystem can be forced to update the attributes >> + * from the backing store by passing AT_FORCE_ATTR_SYNC in query_flags or can >> + * suppress the update by passing AT_NO_ATTR_SYNC. >> + * >> + * Bits must have been set in stat->request_mask to indicate which attributes >> + * the caller wants retrieving. Any such attribute not requested may be >> + * returned anyway, but the value may be approximate, and, if remote, may not >> + * have been synchronised with the server. >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> +int vfs_xgetattr(struct path *path, struct kstat *stat) >> { >> int retval; >> >> retval = security_inode_getattr(path); >> if (retval) >> return retval; >> - return vfs_getattr_nosec(path, stat); >> + return vfs_xgetattr_nosec(path, stat); >> } >> +EXPORT_SYMBOL(vfs_xgetattr); >> >> +/** >> + * vfs_getattr - Get the basic attributes of a file >> + * @path: The file of interest >> + * @stat: Where to return the statistics >> + * >> + * Ask the filesystem for a file's attributes. If remote, the filesystem isn't >> + * forced to update its files from the backing store. Only the basic set of >> + * attributes will be retrieved; anyone wanting more must use vfs_xgetattr(), >> + * as must anyone who wants to force attributes to be sync'd with the server. >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> +int vfs_getattr(struct path *path, struct kstat *stat) >> +{ >> + stat->query_flags = 0; >> + stat->request_mask = STATX_BASIC_STATS; >> + return vfs_xgetattr(path, stat); >> +} >> EXPORT_SYMBOL(vfs_getattr); >> >> -int vfs_fstat(unsigned int fd, struct kstat *stat) >> +/** >> + * vfs_fstatx - Get the enhanced basic attributes by file descriptor >> + * @fd: The file descriptor referring to the file of interest >> + * @stat: The result structure to fill in. >> + * >> + * This function is a wrapper around vfs_xgetattr(). The main difference is >> + * that it uses a file descriptor to determine the file location. >> + * >> + * The caller must have preset stat->query_flags and stat->request_mask as for >> + * vfs_xgetattr(). >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> +int vfs_fstatx(unsigned int fd, struct kstat *stat) >> { >> struct fd f = fdget_raw(fd); >> int error = -EBADF; >> >> if (f.file) { >> - error = vfs_getattr(&f.file->f_path, stat); >> + error = vfs_xgetattr(&f.file->f_path, stat); >> fdput(f); >> } >> return error; >> } >> +EXPORT_SYMBOL(vfs_fstatx); >> + >> +/** >> + * vfs_fstat - Get basic attributes by file descriptor >> + * @fd: The file descriptor referring to the file of interest >> + * @stat: The result structure to fill in. >> + * >> + * This function is a wrapper around vfs_getattr(). The main difference is >> + * that it uses a file descriptor to determine the file location. >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> +int vfs_fstat(unsigned int fd, struct kstat *stat) >> +{ >> + stat->query_flags = 0; >> + stat->request_mask = STATX_BASIC_STATS; >> + return vfs_fstatx(fd, stat); >> +} >> EXPORT_SYMBOL(vfs_fstat); >> >> -int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, >> - int flag) >> +/** >> + * vfs_statx - Get basic and extra attributes by filename >> + * @dfd: A file descriptor representing the base dir for a relative filename >> + * @filename: The name of the file of interest >> + * @flags: Flags to control the query >> + * @stat: The result structure to fill in. >> + * >> + * This function is a wrapper around vfs_xgetattr(). The main difference is >> + * that it uses a filename and base directory to determine the file location. >> + * Additionally, the addition of AT_SYMLINK_NOFOLLOW to flags will prevent a >> + * symlink at the given name from being referenced. >> + * >> + * The caller must have preset stat->request_mask as for vfs_xgetattr(). The >> + * flags are also used to load up stat->query_flags. >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> +int vfs_statx(int dfd, const char __user *filename, int flags, >> + struct kstat *stat) >> { >> struct path path; >> int error = -EINVAL; >> - unsigned int lookup_flags = 0; >> + unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT; >> >> - if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | >> - AT_EMPTY_PATH)) != 0) >> - goto out; >> + if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | >> + AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0) >> + return -EINVAL; >> >> - if (!(flag & AT_SYMLINK_NOFOLLOW)) >> - lookup_flags |= LOOKUP_FOLLOW; >> - if (flag & AT_EMPTY_PATH) >> + if (flags & AT_SYMLINK_NOFOLLOW) >> + lookup_flags &= ~LOOKUP_FOLLOW; >> + if (flags & AT_NO_AUTOMOUNT) >> + lookup_flags &= ~LOOKUP_AUTOMOUNT; >> + if (flags & AT_EMPTY_PATH) >> lookup_flags |= LOOKUP_EMPTY; >> + stat->query_flags = flags; >> + >> retry: >> error = user_path_at(dfd, filename, lookup_flags, &path); >> if (error) >> goto out; >> >> - error = vfs_getattr(&path, stat); >> + error = vfs_xgetattr(&path, stat); >> path_put(&path); >> if (retry_estale(error, lookup_flags)) { >> lookup_flags |= LOOKUP_REVAL; >> @@ -116,17 +227,65 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, >> out: >> return error; >> } >> +EXPORT_SYMBOL(vfs_statx); >> + >> +/** >> + * vfs_fstatat - Get basic attributes by filename >> + * @dfd: A file descriptor representing the base dir for a relative filename >> + * @filename: The name of the file of interest >> + * @flags: Flags to control the query >> + * @stat: The result structure to fill in. >> + * >> + * This function is a wrapper around vfs_statx(). The difference is that it >> + * preselects basic stats only. The flags are used to load up >> + * stat->query_flags in addition to indicating symlink handling during path >> + * resolution. >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> +int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, >> + int flags) >> +{ >> + stat->request_mask = STATX_BASIC_STATS; >> + return vfs_statx(dfd, filename, flags, stat); >> +} >> EXPORT_SYMBOL(vfs_fstatat); >> >> -int vfs_stat(const char __user *name, struct kstat *stat) >> +/** >> + * vfs_stat - Get basic attributes by filename >> + * @filename: The name of the file of interest >> + * @stat: The result structure to fill in. >> + * >> + * This function is a wrapper around vfs_statx(). The difference is that it >> + * preselects basic stats only, terminal symlinks are followed regardless and a >> + * remote filesystem can't be forced to query the server. If such is desired, >> + * vfs_statx() should be used instead. >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> +int vfs_stat(const char __user *filename, struct kstat *stat) >> { >> - return vfs_fstatat(AT_FDCWD, name, stat, 0); >> + stat->request_mask = STATX_BASIC_STATS; >> + return vfs_statx(AT_FDCWD, filename, 0, stat); >> } >> EXPORT_SYMBOL(vfs_stat); >> >> +/** >> + * vfs_lstat - Get basic attrs by filename, without following terminal symlink >> + * @filename: The name of the file of interest >> + * @stat: The result structure to fill in. >> + * >> + * This function is a wrapper around vfs_statx(). The difference is that it >> + * preselects basic stats only, terminal symlinks are note followed regardless >> + * and a remote filesystem can't be forced to query the server. If such is >> + * desired, vfs_statx() should be used instead. >> + * >> + * 0 will be returned on success, and a -ve error code if unsuccessful. >> + */ >> int vfs_lstat(const char __user *name, struct kstat *stat) >> { >> - return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW); >> + stat->request_mask = STATX_BASIC_STATS; >> + return vfs_statx(AT_FDCWD, name, AT_SYMLINK_NOFOLLOW, stat); >> } >> EXPORT_SYMBOL(vfs_lstat); >> >> @@ -141,7 +300,7 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta >> { >> static int warncount = 5; >> struct __old_kernel_stat tmp; >> - >> + >> if (warncount > 0) { >> warncount--; >> printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n", >> @@ -166,7 +325,7 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta >> #if BITS_PER_LONG == 32 >> if (stat->size > MAX_NON_LFS) >> return -EOVERFLOW; >> -#endif >> +#endif >> tmp.st_size = stat->size; >> tmp.st_atime = stat->atime.tv_sec; >> tmp.st_mtime = stat->mtime.tv_sec; >> @@ -443,6 +602,79 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename, >> } >> #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */ >> >> +/* >> + * Set the statx results. >> + */ >> +static long statx_set_result(struct kstat *stat, struct statx __user *buffer) >> +{ >> + uid_t uid = from_kuid_munged(current_user_ns(), stat->uid); >> + gid_t gid = from_kgid_munged(current_user_ns(), stat->gid); >> + >> +#define __put_timestamp(kts, uts) ( \ >> + __put_user(kts.tv_sec, uts##_s ) || \ >> + __put_user(kts.tv_nsec, uts##_ns )) >> + >> + if (__put_user(stat->result_mask, &buffer->stx_mask ) || >> + __put_user(stat->mode, &buffer->stx_mode ) || >> + __clear_user(&buffer->__spare0, sizeof(buffer->__spare0)) || >> + __put_user(stat->nlink, &buffer->stx_nlink ) || >> + __put_user(uid, &buffer->stx_uid ) || >> + __put_user(gid, &buffer->stx_gid ) || >> + __put_user(stat->attributes, &buffer->stx_attributes ) || >> + __put_user(stat->blksize, &buffer->stx_blksize ) || >> + __put_user(MAJOR(stat->rdev), &buffer->stx_rdev_major ) || >> + __put_user(MINOR(stat->rdev), &buffer->stx_rdev_minor ) || >> + __put_user(MAJOR(stat->dev), &buffer->stx_dev_major ) || >> + __put_user(MINOR(stat->dev), &buffer->stx_dev_minor ) || >> + __put_timestamp(stat->atime, &buffer->stx_atime ) || >> + __put_timestamp(stat->btime, &buffer->stx_btime ) || >> + __put_timestamp(stat->ctime, &buffer->stx_ctime ) || >> + __put_timestamp(stat->mtime, &buffer->stx_mtime ) || >> + __put_user(stat->ino, &buffer->stx_ino ) || >> + __put_user(stat->size, &buffer->stx_size ) || >> + __put_user(stat->blocks, &buffer->stx_blocks ) || >> + __put_user(stat->version, &buffer->stx_version ) || >> + __clear_user(&buffer->__spare1, sizeof(buffer->__spare1))) >> + return -EFAULT; >> + >> + return 0; >> +} >> + >> +/** >> + * sys_statx - System call to get enhanced stats >> + * @dfd: Base directory to pathwalk from *or* fd to stat. >> + * @filename: File to stat *or* NULL. >> + * @flags: AT_* flags to control pathwalk. >> + * @mask: Parts of statx struct actually required. >> + * @buffer: Result buffer. >> + * >> + * Note that if filename is NULL, then it does the equivalent of fstat() using >> + * dfd to indicate the file of interest. >> + */ >> +SYSCALL_DEFINE5(statx, >> + int, dfd, const char __user *, filename, unsigned, flags, >> + unsigned int, mask, >> + struct statx __user *, buffer) >> +{ >> + struct kstat stat; >> + int error; >> + >> + if (!access_ok(VERIFY_WRITE, buffer, sizeof(*buffer))) >> + return -EFAULT; >> + >> + memset(&stat, 0, sizeof(stat)); >> + stat.query_flags = flags; >> + stat.request_mask = mask & STATX_ALL; >> + >> + if (filename) >> + error = vfs_statx(dfd, filename, flags, &stat); >> + else >> + error = vfs_fstatx(dfd, &stat); >> + if (error) >> + return error; >> + return statx_set_result(&stat, buffer); >> +} >> + >> /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */ >> void __inode_add_bytes(struct inode *inode, loff_t bytes) >> { >> diff --git a/include/linux/fs.h b/include/linux/fs.h >> index 16d2b6e874d6..f153199566b4 100644 >> --- a/include/linux/fs.h >> +++ b/include/linux/fs.h >> @@ -2916,8 +2916,9 @@ extern const struct inode_operations page_symlink_inode_operations; >> extern void kfree_link(void *); >> extern int generic_readlink(struct dentry *, char __user *, int); >> extern void generic_fillattr(struct inode *, struct kstat *); >> -int vfs_getattr_nosec(struct path *path, struct kstat *stat); >> +extern int vfs_xgetattr_nosec(struct path *path, struct kstat *stat); >> extern int vfs_getattr(struct path *, struct kstat *); >> +extern int vfs_xgetattr(struct path *, struct kstat *); >> void __inode_add_bytes(struct inode *inode, loff_t bytes); >> void inode_add_bytes(struct inode *inode, loff_t bytes); >> void __inode_sub_bytes(struct inode *inode, loff_t bytes); >> @@ -2935,6 +2936,8 @@ extern int vfs_lstat(const char __user *, struct kstat *); >> extern int vfs_fstat(unsigned int, struct kstat *); >> extern int vfs_fstatat(int , const char __user *, struct kstat *, int); >> extern const char *vfs_get_link(struct dentry *, struct delayed_call *); >> +extern int vfs_xstat(int, const char __user *, int, struct kstat *); >> +extern int vfs_xfstat(unsigned int, struct kstat *); >> >> extern int __generic_block_fiemap(struct inode *inode, >> struct fiemap_extent_info *fieinfo, >> diff --git a/include/linux/stat.h b/include/linux/stat.h >> index 075cb0c7eb2a..cf25bb5cf754 100644 >> --- a/include/linux/stat.h >> +++ b/include/linux/stat.h >> @@ -19,19 +19,26 @@ >> #include <linux/uidgid.h> >> >> struct kstat { >> - u64 ino; >> - dev_t dev; >> + u32 query_flags; /* Operational flags */ >> +#define KSTAT_QUERY_FLAGS (AT_STATX_FORCE_SYNC | AT_STATX_DONT_SYNC) >> + u32 request_mask; /* What fields the user asked for */ >> + u32 result_mask; /* What fields the user got */ >> umode_t mode; >> unsigned int nlink; >> + uint32_t blksize; /* Preferred I/O size */ >> + u64 attributes; >> + u64 ino; >> + dev_t dev; >> + dev_t rdev; >> kuid_t uid; >> kgid_t gid; >> - dev_t rdev; >> loff_t size; >> - struct timespec atime; >> + struct timespec atime; >> struct timespec mtime; >> struct timespec ctime; >> - unsigned long blksize; >> - unsigned long long blocks; >> + struct timespec btime; /* File creation time */ >> + u64 blocks; >> + u64 version; /* Data version */ >> }; >> >> #endif >> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h >> index 91a740f6b884..980c3c9b06f8 100644 >> --- a/include/linux/syscalls.h >> +++ b/include/linux/syscalls.h >> @@ -48,6 +48,7 @@ struct stat; >> struct stat64; >> struct statfs; >> struct statfs64; >> +struct statx; >> struct __sysctl_args; >> struct sysinfo; >> struct timespec; >> @@ -902,5 +903,7 @@ asmlinkage long sys_pkey_mprotect(unsigned long start, size_t len, >> unsigned long prot, int pkey); >> asmlinkage long sys_pkey_alloc(unsigned long flags, unsigned long init_val); >> asmlinkage long sys_pkey_free(int pkey); >> +asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags, >> + unsigned mask, struct statx __user *buffer); >> >> #endif >> diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h >> index beed138bd359..c49cb6edaafa 100644 >> --- a/include/uapi/linux/fcntl.h >> +++ b/include/uapi/linux/fcntl.h >> @@ -62,6 +62,8 @@ >> #define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */ >> #define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */ >> #define AT_EMPTY_PATH 0x1000 /* Allow empty relative pathname */ >> +#define AT_STATX_FORCE_SYNC 0x2000 /* Force the attributes to be sync'd with the server */ >> +#define AT_STATX_DONT_SYNC 0x4000 /* Don't sync attributes with the server */ >> >> >> #endif /* _UAPI_LINUX_FCNTL_H */ >> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h >> index 7fec7e36d921..32ea14c1c960 100644 >> --- a/include/uapi/linux/stat.h >> +++ b/include/uapi/linux/stat.h >> @@ -1,6 +1,7 @@ >> #ifndef _UAPI_LINUX_STAT_H >> #define _UAPI_LINUX_STAT_H >> >> +#include <linux/types.h> >> >> #if defined(__KERNEL__) || !defined(__GLIBC__) || (__GLIBC__ < 2) >> >> @@ -41,5 +42,128 @@ >> >> #endif >> >> +/* >> + * Structures for the extended file attribute retrieval system call >> + * (statx()). >> + * >> + * The caller passes a mask of what they're specifically interested in as a >> + * parameter to statx(). What statx() actually got will be indicated in >> + * st_mask upon return. >> + * >> + * For each bit in the mask argument: >> + * >> + * - if the datum is not supported: >> + * >> + * - the bit will be cleared, and >> + * >> + * - the datum will be set to an appropriate fabricated value if one is >> + * available (eg. CIFS can take a default uid and gid), otherwise >> + * >> + * - the field will be cleared; >> + * >> + * - otherwise, if explicitly requested: >> + * >> + * - the datum will be synchronised to the server if AT_STATX_FORCE_SYNC is >> + * set or if the datum is considered out of date, and >> + * >> + * - the field will be filled in and the bit will be set; >> + * >> + * - otherwise, if not requested, but available in approximate form without any >> + * effort, it will be filled in anyway, and the bit will be set upon return >> + * (it might not be up to date, however, and no attempt will be made to >> + * synchronise the internal state first); >> + * >> + * - otherwise the field and the bit will be cleared before returning. >> + * >> + * Items in STATX_BASIC_STATS may be marked unavailable on return, but they >> + * will have values installed for compatibility purposes so that stat() and >> + * co. can be emulated in userspace. >> + */ >> +struct statx { >> + /* 0x00 */ >> + __u32 stx_mask; /* What results were written [uncond] */ >> + __u32 stx_blksize; /* Preferred general I/O size [uncond] */ >> + __u64 stx_attributes; /* Flags conveying information about the file [uncond] */ >> + /* 0x10 */ >> + __u32 stx_nlink; /* Number of hard links */ >> + __u32 stx_uid; /* User ID of owner */ >> + __u32 stx_gid; /* Group ID of owner */ >> + __u16 stx_mode; /* File mode */ >> + __u16 __spare0[1]; >> + /* 0x20 */ >> + __u64 stx_ino; /* Inode number */ >> + __u64 stx_size; /* File size */ >> + __u64 stx_blocks; /* Number of 512-byte blocks allocated */ >> + __u64 stx_version; /* Data version number */ >> + /* 0x40 */ >> + __s64 stx_atime_s; /* Last access time */ >> + __s64 stx_btime_s; /* File creation time */ >> + __s64 stx_ctime_s; /* Last attribute change time */ >> + __s64 stx_mtime_s; /* Last data modification time */ >> + /* 0x60 */ >> + __s32 stx_atime_ns; /* Last access time (ns part) */ >> + __s32 stx_btime_ns; /* File creation time (ns part) */ >> + __s32 stx_ctime_ns; /* Last attribute change time (ns part) */ >> + __s32 stx_mtime_ns; /* Last data modification time (ns part) */ >> + /* 0x70 */ >> + __u32 stx_rdev_major; /* Device ID of special file [if bdev/cdev] */ >> + __u32 stx_rdev_minor; >> + __u32 stx_dev_major; /* ID of device containing file [uncond] */ >> + __u32 stx_dev_minor; >> + /* 0x80 */ >> + __u64 __spare1[16]; /* Spare space for future expansion */ >> + /* 0x100 */ >> +}; >> + >> +/* >> + * Flags to be stx_mask >> + * >> + * Query request/result mask for statx() and struct statx::stx_mask. >> + * >> + * These bits should be set in the mask argument of statx() to request >> + * particular items when calling statx(). >> + */ >> +#define STATX_TYPE 0x00000001U /* Want/got stx_mode & S_IFMT */ >> +#define STATX_MODE 0x00000002U /* Want/got stx_mode & ~S_IFMT */ >> +#define STATX_NLINK 0x00000004U /* Want/got stx_nlink */ >> +#define STATX_UID 0x00000008U /* Want/got stx_uid */ >> +#define STATX_GID 0x00000010U /* Want/got stx_gid */ >> +#define STATX_ATIME 0x00000020U /* Want/got stx_atime */ >> +#define STATX_MTIME 0x00000040U /* Want/got stx_mtime */ >> +#define STATX_CTIME 0x00000080U /* Want/got stx_ctime */ >> +#define STATX_INO 0x00000100U /* Want/got stx_ino */ >> +#define STATX_SIZE 0x00000200U /* Want/got stx_size */ >> +#define STATX_BLOCKS 0x00000400U /* Want/got stx_blocks */ >> +#define STATX_BASIC_STATS 0x000007ffU /* The stuff in the normal stat struct */ >> +#define STATX_BTIME 0x00000800U /* Want/got stx_btime */ >> +#define STATX_VERSION 0x00001000U /* Want/got stx_version */ >> +#define STATX_ALL 0x00001fffU /* All currently supported flags */ >> + >> +/* >> + * Attributes to be found in stx_attributes >> + * >> + * These give information about the features or the state of a file that might >> + * be of use to ordinary userspace programs such as GUIs or ls rather than >> + * specialised tools. >> + * >> + * Note that the flags marked [I] correspond to generic FS_IOC_FLAGS >> + * semantically. Where possible, the numerical value is picked to correspond >> + * also. >> + */ >> +#define STATX_ATTR_COMPRESSED 0x00000004 /* [I] File is compressed by the fs */ >> +#define STATX_ATTR_IMMUTABLE 0x00000010 /* [I] File is marked immutable */ >> +#define STATX_ATTR_APPEND 0x00000020 /* [I] File is append-only */ >> +#define STATX_ATTR_NODUMP 0x00000040 /* [I] File is not to be dumped */ >> +#define STATX_ATTR_NONUNIX_OWNERSHIP 0x00000100 /* File has non-Unix ownership details */ >> +#define STATX_ATTR_HAS_ACL 0x00000200 /* File has an ACL */ >> +#define STATX_ATTR_ENCRYPTED 0x00000800 /* [I] File requires key to decrypt in fs */ >> +#define STATX_ATTR_FS_IOC_FLAGS 0x00000874 /* Attrs corresponding to FS_*_FL flags */ >> + >> +#define STATX_ATTR_KERNEL_API 0x00001000 /* File is kernel API (eg: procfs/sysfs) */ >> +#define STATX_ATTR_REMOTE 0x00002000 /* File is remote and needs network */ >> +#define STATX_ATTR_FABRICATED 0x00004000 /* File was made up by fs and is transient */ >> +#define STATX_ATTR_AUTOMOUNT 0x00008000 /* Dir: Automount trigger */ >> +#define STATX_ATTR_UNLISTED_DENTS 0x00010000 /* Dir: Lookup may find files getdents doesn't */ >> + >> >> #endif /* _UAPI_LINUX_STAT_H */ >> diff --git a/samples/Kconfig b/samples/Kconfig >> index a6d2a43bbf2e..94a7488f14ae 100644 >> --- a/samples/Kconfig >> +++ b/samples/Kconfig >> @@ -105,4 +105,9 @@ config SAMPLE_BLACKFIN_GPTIMERS >> help >> Build samples of blackfin gptimers sample module. >> >> +config SAMPLE_STATX >> + bool "Build example extended-stat using code" >> + help >> + Build example userspace program to use the new extended-stat syscall. >> + >> endif # SAMPLES >> diff --git a/samples/Makefile b/samples/Makefile >> index e17d66d77f09..8eeb15e13413 100644 >> --- a/samples/Makefile >> +++ b/samples/Makefile >> @@ -2,4 +2,5 @@ >> >> obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \ >> hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \ >> - configfs/ connector/ v4l/ trace_printk/ blackfin/ >> + configfs/ connector/ v4l/ trace_printk/ blackfin/ \ >> + statx/ >> diff --git a/samples/statx/Makefile b/samples/statx/Makefile >> new file mode 100644 >> index 000000000000..1f80a3d8cf45 >> --- /dev/null >> +++ b/samples/statx/Makefile >> @@ -0,0 +1,10 @@ >> +# kbuild trick to avoid linker error. Can be omitted if a module is built. >> +obj- := dummy.o >> + >> +# List of programs to build >> +hostprogs-$(CONFIG_SAMPLE_STATX) := test-statx >> + >> +# Tell kbuild to always build the programs >> +always := $(hostprogs-y) >> + >> +HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include >> diff --git a/samples/statx/test-statx.c b/samples/statx/test-statx.c >> new file mode 100644 >> index 000000000000..2419b33fc15d >> --- /dev/null >> +++ b/samples/statx/test-statx.c >> @@ -0,0 +1,248 @@ >> +/* Test the statx() system call >> + * >> + * Copyright (C) 2015 Red Hat, Inc. All Rights Reserved. >> + * Written by David Howells (dhowells@redhat.com) >> + * >> + * This program is free software; you can redistribute it and/or >> + * modify it under the terms of the GNU General Public Licence >> + * as published by the Free Software Foundation; either version >> + * 2 of the Licence, or (at your option) any later version. >> + */ >> + >> +#define _GNU_SOURCE >> +#define _ATFILE_SOURCE >> +#include <stdio.h> >> +#include <stdlib.h> >> +#include <string.h> >> +#include <unistd.h> >> +#include <ctype.h> >> +#include <errno.h> >> +#include <time.h> >> +#include <sys/syscall.h> >> +#include <sys/types.h> >> +#include <linux/stat.h> >> +#include <linux/fcntl.h> >> +#include <sys/stat.h> >> + >> +#define AT_STATX_FORCE_SYNC 0x2000 >> +#define AT_STATX_DONT_SYNC 0x4000 >> + >> +static __attribute__((unused)) >> +ssize_t statx(int dfd, const char *filename, unsigned flags, >> + unsigned int mask, struct statx *buffer) >> +{ >> + return syscall(__NR_statx, dfd, filename, flags, mask, buffer); >> +} >> + >> +static void print_time(const char *field, __s64 tv_sec, __s32 tv_nsec) >> +{ >> + struct tm tm; >> + time_t tim; >> + char buffer[100]; >> + int len; >> + >> + tim = tv_sec; >> + if (!localtime_r(&tim, &tm)) { >> + perror("localtime_r"); >> + exit(1); >> + } >> + len = strftime(buffer, 100, "%F %T", &tm); >> + if (len == 0) { >> + perror("strftime"); >> + exit(1); >> + } >> + printf("%s", field); >> + fwrite(buffer, 1, len, stdout); >> + printf(".%09u", tv_nsec); >> + len = strftime(buffer, 100, "%z", &tm); >> + if (len == 0) { >> + perror("strftime2"); >> + exit(1); >> + } >> + fwrite(buffer, 1, len, stdout); >> + printf("\n"); >> +} >> + >> +static void dump_statx(struct statx *stx) >> +{ >> + char buffer[256], ft = '?'; >> + >> + printf("results=%x\n", stx->stx_mask); >> + >> + printf(" "); >> + if (stx->stx_mask & STATX_SIZE) >> + printf(" Size: %-15llu", (unsigned long long)stx->stx_size); >> + if (stx->stx_mask & STATX_BLOCKS) >> + printf(" Blocks: %-10llu", (unsigned long long)stx->stx_blocks); >> + printf(" IO Block: %-6llu ", (unsigned long long)stx->stx_blksize); >> + if (stx->stx_mask & STATX_MODE) { >> + switch (stx->stx_mode & S_IFMT) { >> + case S_IFIFO: printf(" FIFO\n"); ft = 'p'; break; >> + case S_IFCHR: printf(" character special file\n"); ft = 'c'; break; >> + case S_IFDIR: printf(" directory\n"); ft = 'd'; break; >> + case S_IFBLK: printf(" block special file\n"); ft = 'b'; break; >> + case S_IFREG: printf(" regular file\n"); ft = '-'; break; >> + case S_IFLNK: printf(" symbolic link\n"); ft = 'l'; break; >> + case S_IFSOCK: printf(" socket\n"); ft = 's'; break; >> + default: >> + printf("unknown type (%o)\n", stx->stx_mode & S_IFMT); >> + break; >> + } >> + } >> + >> + sprintf(buffer, "%02x:%02x", stx->stx_dev_major, stx->stx_dev_minor); >> + printf("Device: %-15s", buffer); >> + if (stx->stx_mask & STATX_INO) >> + printf(" Inode: %-11llu", (unsigned long long) stx->stx_ino); >> + if (stx->stx_mask & STATX_SIZE) >> + printf(" Links: %-5u", stx->stx_nlink); >> + switch (stx->stx_mask & STATX_MODE) { >> + case S_IFBLK: >> + case S_IFCHR: >> + printf(" Device type: %u,%u", stx->stx_rdev_major, stx->stx_rdev_minor); >> + break; >> + } >> + printf("\n"); >> + >> + if (stx->stx_mask & STATX_MODE) >> + printf("Access: (%04o/%c%c%c%c%c%c%c%c%c%c) ", >> + stx->stx_mode & 07777, >> + ft, >> + stx->stx_mode & S_IRUSR ? 'r' : '-', >> + stx->stx_mode & S_IWUSR ? 'w' : '-', >> + stx->stx_mode & S_IXUSR ? 'x' : '-', >> + stx->stx_mode & S_IRGRP ? 'r' : '-', >> + stx->stx_mode & S_IWGRP ? 'w' : '-', >> + stx->stx_mode & S_IXGRP ? 'x' : '-', >> + stx->stx_mode & S_IROTH ? 'r' : '-', >> + stx->stx_mode & S_IWOTH ? 'w' : '-', >> + stx->stx_mode & S_IXOTH ? 'x' : '-'); >> + if (stx->stx_mask & STATX_UID) >> + printf("Uid: %5d ", stx->stx_uid); >> + if (stx->stx_mask & STATX_GID) >> + printf("Gid: %5d\n", stx->stx_gid); >> + >> + if (stx->stx_mask & STATX_ATIME) >> + print_time("Access: ", stx->stx_atime_s, stx->stx_atime_ns); >> + if (stx->stx_mask & STATX_MTIME) >> + print_time("Modify: ", stx->stx_mtime_s, stx->stx_mtime_ns); >> + if (stx->stx_mask & STATX_CTIME) >> + print_time("Change: ", stx->stx_ctime_s, stx->stx_ctime_ns); >> + if (stx->stx_mask & STATX_BTIME) >> + print_time(" Birth: ", stx->stx_btime_s, stx->stx_btime_ns); >> + >> + if (stx->stx_mask & STATX_VERSION) >> + printf("Data version: %llxh\n", >> + (unsigned long long)stx->stx_version); >> + >> + if (stx->stx_attributes) { >> + unsigned char bits; >> + int loop, byte; >> + >> + static char attr_representation[64 + 1] = >> + /* STATX_ATTR_ flags: */ >> + "????????" /* 63-56 */ >> + "????????" /* 55-48 */ >> + "????????" /* 47-40 */ >> + "????????" /* 39-32 */ >> + "????????" /* 31-24 0x00000000-ff000000 */ >> + "???????u" /* 23-16 0x00000000-00ff0000 */ >> + "mfrke?AU" /* 15- 8 0x00000000-0000ff00 */ >> + "?dai?c??" /* 7- 0 0x00000000-000000ff */ >> + ; >> + >> + printf("Attributes: %016llx (", stx->stx_attributes); >> + for (byte = 64 - 8; byte >= 0; byte -= 8) { >> + bits = stx->stx_attributes >> byte; >> + for (loop = 7; loop >= 0; loop--) { >> + int bit = byte + loop; >> + >> + if (bits & 0x80) >> + putchar(attr_representation[63 - bit]); >> + else >> + putchar('-'); >> + bits <<= 1; >> + } >> + if (byte) >> + putchar(' '); >> + } >> + printf(")\n"); >> + } >> + >> + printf("IO-blocksize: blksize=%u\n", stx->stx_blksize); >> +} >> + >> +static void dump_hex(unsigned long long *data, int from, int to) >> +{ >> + unsigned offset, print_offset = 1, col = 0; >> + >> + from /= 8; >> + to = (to + 7) / 8; >> + >> + for (offset = from; offset < to; offset++) { >> + if (print_offset) { >> + printf("%04x: ", offset * 8); >> + print_offset = 0; >> + } >> + printf("%016llx", data[offset]); >> + col++; >> + if ((col & 3) == 0) { >> + printf("\n"); >> + print_offset = 1; >> + } else { >> + printf(" "); >> + } >> + } >> + >> + if (!print_offset) >> + printf("\n"); >> +} >> + >> +int main(int argc, char **argv) >> +{ >> + struct statx stx; >> + int ret, raw = 0, atflag = AT_SYMLINK_NOFOLLOW; >> + >> + unsigned int mask = STATX_ALL; >> + >> + for (argv++; *argv; argv++) { >> + if (strcmp(*argv, "-F") == 0) { >> + atflag |= AT_STATX_FORCE_SYNC; >> + continue; >> + } >> + if (strcmp(*argv, "-D") == 0) { >> + atflag |= AT_STATX_DONT_SYNC; >> + continue; >> + } >> + if (strcmp(*argv, "-L") == 0) { >> + atflag &= ~AT_SYMLINK_NOFOLLOW; >> + continue; >> + } >> + if (strcmp(*argv, "-O") == 0) { >> + mask &= ~STATX_BASIC_STATS; >> + continue; >> + } >> + if (strcmp(*argv, "-A") == 0) { >> + atflag |= AT_NO_AUTOMOUNT; >> + continue; >> + } >> + if (strcmp(*argv, "-R") == 0) { >> + raw = 1; >> + continue; >> + } >> + >> + memset(&stx, 0xbf, sizeof(stx)); >> + ret = statx(AT_FDCWD, *argv, atflag, mask, &stx); >> + printf("statx(%s) = %d\n", *argv, ret); >> + if (ret < 0) { >> + perror(*argv); >> + exit(1); >> + } >> + >> + if (raw) >> + dump_hex((unsigned long long *)&stx, 0, sizeof(stx)); >> + >> + dump_statx(&stx); >> + } >> + return 0; >> +} >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > Jeff Layton <jlayton@redhat.com> > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Cheers, Andreas
On Nov 17, 2016, at 4:40 PM, Dave Chinner <david@fromorbit.com> wrote: > > On Thu, Nov 17, 2016 at 01:35:03PM +0000, David Howells wrote: >> Add a system call to make extended file information available, including >> file creation, data version and some attribute flags where available >> through the underlying filesystem. >> >> >> ======== >> OVERVIEW >> ======== >> >> The idea was initially proposed as a set of xattrs that could be retrieved >> with getxattr(), but the general preferance proved to be for a new syscall >> with an extended stat structure. >> >> This has a number of uses: >> > .... >> (5) Data version number: Could be used by userspace NFS servers [Aneesh >> Kumar]. >> >> Can also be used to modify fill_post_wcc() in NFSD which retrieves >> i_version directly, but has just called vfs_getattr(). It could get >> it from the kstat struct if it used vfs_xgetattr() instead. > > This needs a much clearer name that stx_version as "version" is > entirely ambiguous. e.g. Inodes have internal version numbers to > disambiguate life cycles. and there are versioning filesystems > which have multiple versions of the same file. > > So if stx_version this is intended to export the internal filesystem > inode change counter (i.e. inode->i_version) then lets call it that: > stx_modification_count. It's clear and unambiguous as to what it > represents, especially as this counter is more than just a "data > modification" counter - inode metadata modifications will also > cause it to change... Honestly, I don't think "modification count" is necessarily more clear than "version". This value isn't necessarily a counter incremented to hold the number of times the inode was modified, but is used by NFS only to determine whether the inode has been modified from one access to the next. It may not be incremented sequentially for each inode, but rather be a global value across all inodes in the filesystem. It is much more important to clearly document what this version field means. Maybe "stx_modification_version", but I'm fine with "version" as well, since this is what the field is named in the kernel. >> (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. >> Note that the Linux IOC flags are a mess and filesystems such as Ext4 >> define flags that aren't in linux/fs.h, so translation in the kernel >> may be a necessity (or, possibly, we provide the filesystem type too). > > And we now also have FS_IOC_FSGETXATTR that extends the flags > and information userspace can get from filesystems. It makes little > sense to now add xstat() and not add everything this interface > also exports... The number of flags available will always be a moving target. Better to get the core functionality landed, and then add in new flags in a later patch, otherwise this patch will never be landed. >> The defined bits in request_mask and stx_mask are: >> >> STATX_TYPE Want/got stx_mode & S_IFMT >> STATX_MODE Want/got stx_mode & ~S_IFMT >> STATX_NLINK Want/got stx_nlink >> STATX_UID Want/got stx_uid >> STATX_GID Want/got stx_gid >> STATX_ATIME Want/got stx_atime{,_ns} >> STATX_MTIME Want/got stx_mtime{,_ns} >> STATX_CTIME Want/got stx_ctime{,_ns} >> STATX_INO Want/got stx_ino >> STATX_SIZE Want/got stx_size >> STATX_BLOCKS Want/got stx_blocks >> STATX_BASIC_STATS [The stuff in the normal stat struct] >> STATX_BTIME Want/got stx_btime{,_ns} >> STATX_VERSION Want/got stx_version >> STATX_ALL [All currently available stuff] > > What happens when an application uses STATX_ALL from a future kernel > that defines more flags than are initially supported, and that > application then is run on a kernel that onyl supports the initial > fields? Fields that are unknown by the current kernel/filesystem will not be set, and this is reflected in the flags that are returned to userspace. The minimum required flags are the intersection of the requested flags from userspace and the flags known by the kernel/filesystem. It is possible for the filesystem to optionally return extra flags/fields if they are free to provide, but it should always return the requested flags *if* it knows what those flags mean. >> stx_btime is the file creation time; stx_version is the data version >> number (i_version); stx_mask is a bitmask indicating the data provided; >> and __spares*[] are where as-yet undefined fields can be placed. >> >> Time fields are split into separate seconds and nanoseconds fields to make >> packing easier and the granularities can be queried with the filesystem >> info system call. Note that times will be negative if before 1970; in >> such a case, the nanosecond fields will also be negative if not zero. > > So what happens in ten years time when we want to support > femptosecond resolution in the timestamp interface? We've got to > change everything to 64 bit? Shouldn't we just make everything > timestamp related 64 bit? Is this a serious request? Are we going to need to multiply everything by 10e9 to convert to/from nanoseconds for the next 10 years on the off chance that we have timestamps more accurate than this in the future? We could just as easily add extra 32-bit fields in the future to hold the fraction of nanoseconds if we ever actually need this. Given that we've totally bailed on keeping accurate atimes below a day, I'm not really worried about needing this. >> The bits defined in the stx_attributes field convey information about a >> file, how it is accessed, where it is and what it does. The following >> attributes map to FS_*_FL flags and are the same numerical value: > > Please isolate the new interface flags completely from the FS_*_FL > values. We should not repeat the mistake of tying values derived > from filesystem specific on-disk values to a user interface. Using the existing FS_*_FL flags as initial values is not worse than starting with any other arbitrary values for the flags. >> STATX_ATTR_COMPRESSED File is compressed by the fs >> STATX_ATTR_IMMUTABLE File is marked immutable >> STATX_ATTR_APPEND File is append-only >> STATX_ATTR_NODUMP File is not to be dumped >> STATX_ATTR_ENCRYPTED File requires key to decrypt in fs >> >> The supported flags are listed by: >> >> STATX_ATTR_FS_IOC_FLAGS > > Again, we have many more common and extended flags than this. > NOATIME and SYNC are two that immediately come to mind as generic > flags that should be in this... Sure, and they can be added incrementally in a later patch. I'm not sure why NOATIME and SYNC are missing, and I'm not against adding them, but it is equally likely that they were removed in a previous round of bikeshedding to avoid some real or perceived issue, so that this patch can finally land rather than being in limbo for another 5 years. >> [Are any other IOC flags of sufficient general interest to be exposed >> through this interface?] >> >> New flags include: >> >> STATX_ATTR_NONUNIX_OWNERSHIP File doesn't have Unixy ownership >> STATX_ATTR_HAS_ACL File has an ACL > > So statx will require us to do ACL lookups? i.e. instead of just > reading the inode to get the information, we'll also have to do > extended attribute lookups? That's potentially very expensive if > the extended attribute is not stored in the inode.... No, there is no requirement to return anything that the caller didn't ask for. Only fields that are explicitly requested need to be returned, and others can optionally be returned if it is easy for the filesystem to do so. >> STATX_ATTR_KERNEL_API File is kernel API (eg: procfs/sysfs) >> STATX_ATTR_REMOTE File is remote and needs network >> STATX_ATTR_FABRICATED File was made up by fs > > Every file is fabricated by a filesystem :P > > Perhaps you're wanting "virtual file" because it is has no physical > presence? > >> Fields in struct statx come in a number of classes: >> >> (0) stx_dev_*, stx_blksize. >> >> These are local system information and are always available. > > What does stx_blksize actually mean? It's completely ambiguous in > stat() because we don't actually report the physical block size > here - we report the "minimum unit of efficient IO" that we expect > applications to use. Please define :P > > >> ======= >> TESTING >> ======= >> >> The following test program can be used to test the statx system call: >> >> samples/statx/test-statx.c >> >> Just compile and run, passing it paths to the files you want to examine. >> The file is built automatically if CONFIG_SAMPLES is enabled. > > Can we get xfstests written to exercise and validate all this > functionality, please? I'd suggest that adding xfs_io support for > the statx syscall would be far more useful for xfstests than a > standalone test program, too. We already have equivalent stat() > functionality in xfs_io and that's used quite a bit in xfstests.... > > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Cheers, Andreas
Jeff Layton <jlayton@redhat.com> wrote: > > If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for > > stat() on that filesystem. > > > > We also need to specify here what happens if both bits are set. Should > that be -EINVAL? Makes sense. This leads to another thought: should fstatat() be allowed to take AT_STATX_* flags? David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Andreas Dilger <adilger@dilger.ca> wrote: > >> If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for > >> stat() on that filesystem. > > > > We also need to specify here what happens if both bits are set. Should > > that be -EINVAL? > > If that is the case, then it doesn't make sense to have two contradictory > flags. Yes it does. There are actually *three* cases, not two. Maybe, rather than a pair of flags, I should stake out a 2-bit field with three possible values. > Pick a default behaviour (i.e. return what is known on the client), The default behaviour has to be what stat() does now for any particular filesystem. statx() is likely to get used to emulate stat() so that stat() can be made to return safe timestamps. If we make it so that statx() cannot do this, it's very likely that we'll see yet another stat() variant syscall being added. > and if this is 100% accurate (e.g. local filesystem or filesystem with > strong coherency) In a netfs, it was 100% accurate at the point the server started transmitting its reply. This may no longer be true - even with something like AFS that has change notifications. > then it can optionally set the SYNC flag in the returned > flags. So you suggest putting the SYNC flag(s) in the request mask rather than sharing the AT_* flag space? > If the application needs 100% accurate size info, then it can set the SYNC > flag in the request and the filesystem may need to do extra work to fetch > accurate data from the server. Note that one of the things that people asked for was a DONT_GO_TO_THE_SERVER_AT_ALL flag. I take it this is your suggested default? David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Nov 18, 2016, at 1:59 AM, David Howells <dhowells@redhat.com> wrote: > > Andreas Dilger <adilger@dilger.ca> wrote: > >>>> If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for >>>> stat() on that filesystem. >>> >>> We also need to specify here what happens if both bits are set. Should >>> that be -EINVAL? >> >> If that is the case, then it doesn't make sense to have two contradictory >> flags. > > Yes it does. There are actually *three* cases, not two. Maybe, rather > than a pair of flags, I should stake out a 2-bit field with three possible > values. That would probably be better in this case. >> Pick a default behaviour (i.e. return what is known on the client), > > The default behaviour has to be what stat() does now for any particular > filesystem. statx() is likely to get used to emulate stat() so that stat() > can be made to return safe timestamps. If we make it so that statx() cannot > do this, it's very likely that we'll see yet another stat() variant syscall > being added. > >> and if this is 100% accurate (e.g. local filesystem or filesystem with >> strong coherency) > > In a netfs, it was 100% accurate at the point the server started > transmitting its reply. This may no longer be true - even with something > like AFS that has change notifications. Sure, that is always true, even when running with a local filesystem. My distinction here is "whether the client currently has a lock that ensures its copy of the size is correct" vs. "the client has some size that was correct at one point but may be totally incorrect now". >> then it can optionally set the SYNC flag in the returned >> flags. > > So you suggest putting the SYNC flag(s) in the request mask rather than > sharing the AT_* flag space? Sorry, I was conflating flags. >> If the application needs 100% accurate size info, then it can set the SYNC >> flag in the request and the filesystem may need to do extra work to fetch >> accurate data from the server. > > Note that one of the things that people asked for was a > DONT_GO_TO_THE_SERVER_AT_ALL flag. I take it this is your suggested default? Isn't that what NFS does today? In any case, I'm not trying to rewrite NFS semantics here. The main fix would be to have the three-valued two-bit flag so that there aren't two flags that mean opposite things. That would also allow expansion to have a fourth state in the future, if there was a need. Cheers, Andreas
Dave Chinner <david@fromorbit.com> wrote: > > (5) Data version number: Could be used by userspace NFS servers [Aneesh > > Kumar]. > > > > Can also be used to modify fill_post_wcc() in NFSD which retrieves > > i_version directly, but has just called vfs_getattr(). It could get > > it from the kstat struct if it used vfs_xgetattr() instead. > > This needs a much clearer name that stx_version as "version" is > entirely ambiguous. e.g. Inodes have internal version numbers to > disambiguate life cycles. and there are versioning filesystems > which have multiple versions of the same file. We've already been through that. I wanted to call it stx_data_version but that got argued down to stx_version. The problem is that what the version number means is entirely filesystem dependent, and it might not just reflect changes in the data. > So if stx_version this is intended to export the internal filesystem > inode change counter (i.e. inode->i_version) then lets call it that: > stx_modification_count. It's clear and unambiguous as to what it > represents, especially as this counter is more than just a "data > modification" counter - inode metadata modifications will also > cause it to change.... I disagree that it's unambiguous. It works like mtime, right? Which wouldn't be of use for certain filesystems. An example of this would be AFS, where it's incremented by 1 each time a write is committed, but is not updated for metadata changes. This is what matters for data caching. > > (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. > > Note that the Linux IOC flags are a mess and filesystems such as Ext4 > > define flags that aren't in linux/fs.h, so translation in the kernel > > may be a necessity (or, possibly, we provide the filesystem type too). > > And we now also have FS_IOC_FSGETXATTR that extends the flags > and information userspace can get from filesystems. It makes little > sense to now add xstat() and not add everything this interface > also exports... I'm not sure I agree. Stuff like extent sizes and extent hint flags seem like very specialised things that don't belong in the stat interface. The project ID, on the other hand is arguably a good thing to include. But we can always add this later. Note that are also two variants of the fsxattr struct defined in the kernel - though one is a superset of the other. > > Time fields are split into separate seconds and nanoseconds fields to make > > packing easier and the granularities can be queried with the filesystem > > info system call. Note that times will be negative if before 1970; in such > > a case, the nanosecond fields will also be negative if not zero. > > So what happens in ten years time when we want to support > femptosecond resolution in the timestamp interface? We've got to > change everything to 64 bit? Shouldn't we just make everything > timestamp related 64 bit? You really think we're going to have accurate timestamps with a resolution of a millionth of a nanosecond? This means you're going to be doing a 64-bit division every time you want a nanosecond timestamp. Also, violet light has a period of ~1.2fs so your 1fs oscillator might emit UV radiation. > > The bits defined in the stx_attributes field convey information about a > > file, how it is accessed, where it is and what it does. The following > > attributes map to FS_*_FL flags and are the same numerical value: > > Please isolate the new interface flags completely from the FS_*_FL > values. We should not repeat the mistake of tying values derived > from filesystem specific on-disk values to a user interface. Why shouldn't I make a numerical correspondance with at least one set of such flags? I get to define a whole new numberspace and can pick the values I want. I see no particular reason to pick explicitly non-corresponding values where possible. Now, I can agree that the code should say, for example: if (ext4->flag & FS_COMPRESSED_FL) statx.attr |= STATX_ATTR_COMPRESSED; if (ext4->flag & FS_ENCRYPTED_FL) statx.attr |= STATX_ATTR_ENCRYPTED; if (ext4->flag & FS_IMMUTABLE_FL) statx.attr |= STATX_ATTR_IMMUTABLE; ... and that the *compiler* should collapse this to: statx.attr |= ext4->flag & mask; but see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78317 David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Dave Chinner <david@fromorbit.com> wrote: > > STATX_ATTR_KERNEL_API File is kernel API (eg: procfs/sysfs) > > STATX_ATTR_REMOTE File is remote and needs network > > STATX_ATTR_FABRICATED File was made up by fs > > Every file is fabricated by a filesystem :P > > Perhaps you're wanting "virtual file" because it is has no physical > presence? Yeah - that might be a better name. The idea of FABRICATED is to note objects that have no actual existence in the backing store. Directories that had to be invented to act as mountpoints would be a good example of this. > > Fields in struct statx come in a number of classes: > > > > (0) stx_dev_*, stx_blksize. > > > > These are local system information and are always available. > > What does stx_blksize actually mean? It's completely ambiguous in > stat() because we don't actually report the physical block size > here - we report the "minimum unit of efficient IO" that we expect > applications to use. Please define :P Definition: "Same as struct stat::st_blksize". > > The following test program can be used to test the statx system call: > > > > samples/statx/test-statx.c > > > > Just compile and run, passing it paths to the files you want to examine. > > The file is built automatically if CONFIG_SAMPLES is enabled. > > Can we get xfstests written to exercise and validate all this > functionality, please? I'd suggest that adding xfs_io support for > the statx syscall would be far more useful for xfstests than a > standalone test program, too. We already have equivalent stat() > functionality in xfs_io and that's used quite a bit in xfstests.... Feel free to write some! ;-) But I need a simple standalone test program to be able to test what I write, and I've no inclination to wheel out huge testsuites for an interface that people are still arguing about and wanting changed. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Andreas Dilger <adilger@dilger.ca> wrote: > > What happens when an application uses STATX_ALL from a future kernel > > that defines more flags than are initially supported, and that > > application then is run on a kernel that onyl supports the initial > > fields? > > Fields that are unknown by the current kernel/filesystem will not be set, > and this is reflected in the flags that are returned to userspace. Yep. A userspace program can stick 0xffffffff in there if it wants. No error will be incurred. It just won't necessarily get anything back for each of those bits. That said, if we, say, want to reserve bit 31 as a struct extension bit, sticking in 0xffffffff without knowing what this is going to do to you on a kernel that supports a longer struct might give you a problem. But, basically, STATX_ALL indicates what flags have fields in the copy of the struct you got from the header file. There's an extra scenario: you could compile your userspace program against the headers for a particular kernel and then run against a later kernel. In such a case, you may find bits set that are outside STATX_ALL in stx_mask. However, you don't have definitions for those bits and can only ignore them. > > Again, we have many more common and extended flags than this. > > NOATIME and SYNC are two that immediately come to mind as generic > > flags that should be in this... > > Sure, and they can be added incrementally in a later patch. I'm not > sure why NOATIME and SYNC are missing, and I'm not against adding them, > but it is equally likely that they were removed in a previous round of > bikeshedding to avoid some real or perceived issue, so that this patch > can finally land rather than being in limbo for another 5 years. Does it make sense to return them through statx? Note that NOATIME might be considered superfluous given that STATX_ATIME is cleared in such a case. > >> New flags include: > >> > >> STATX_ATTR_NONUNIX_OWNERSHIP File doesn't have Unixy ownership > >> STATX_ATTR_HAS_ACL File has an ACL > > > > So statx will require us to do ACL lookups? i.e. instead of just > > reading the inode to get the information, we'll also have to do > > extended attribute lookups? That's potentially very expensive if > > the extended attribute is not stored in the inode.... > > No, there is no requirement to return anything that the caller didn't > ask for. Only fields that are explicitly requested need to be returned, > and others can optionally be returned if it is easy for the filesystem > to do so. Actually, Dave might have a point. We don't necessarily know that the file has an ACL without doing a getxattr() to probe for it - on the other hand, I would expect the permissions check to have done precisely that. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Dave Chinner <david@fromorbit.com> wrote: > > (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. > > Note that the Linux IOC flags are a mess and filesystems such as Ext4 > > define flags that aren't in linux/fs.h, so translation in the kernel > > may be a necessity (or, possibly, we provide the filesystem type too). > > And we now also have FS_IOC_FSGETXATTR that extends the flags > and information userspace can get from filesystems. Btw, can you point me at the manpage that defines the fsxattr struct and its flags? Also, ioctl_list(2) should probably include FS_IOC_FS[GS]ETXATTR. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2016-11-18 at 08:48 +0000, David Howells wrote: > Jeff Layton <jlayton@redhat.com> wrote: > > > > > > > > > If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for > > > stat() on that filesystem. > > > > > > > We also need to specify here what happens if both bits are set. Should > > that be -EINVAL? > > Makes sense. > > This leads to another thought: should fstatat() be allowed to take AT_STATX_* > flags? > > David In principle, we could. fstatat currently rejects flags that it doesn't understand with -EINVAL. That said, I'd vote no -- if you wanted to change an application to start setting these flags in fstatat calls, then it's just as simple to convert it over to use statx. I don't see a lot of benefit in adding that to a legacy syscall.
On Fri, 2016-11-18 at 09:36 +0000, David Howells wrote: > Dave Chinner <david@fromorbit.com> wrote: > > > > (5) Data version number: Could be used by userspace NFS servers [Aneesh > > > Kumar]. > > > > > > Can also be used to modify fill_post_wcc() in NFSD which retrieves > > > i_version directly, but has just called vfs_getattr(). It could get > > > it from the kstat struct if it used vfs_xgetattr() instead. > > > > This needs a much clearer name that stx_version as "version" is > > entirely ambiguous. e.g. Inodes have internal version numbers to > > disambiguate life cycles. and there are versioning filesystems > > which have multiple versions of the same file. > > We've already been through that. I wanted to call it stx_data_version but > that got argued down to stx_version. The problem is that what the version > number means is entirely filesystem dependent, and it might not just reflect > changes in the data. > It had better not just reflect data changes. knfsd populates the NFSv4 change attribute from inode->i_version. It _must_ have changed between subsequent queries if either the data or metadata has changed (basically whenever you would update either the ctime or the mtime). > > So if stx_version this is intended to export the internal filesystem > > inode change counter (i.e. inode->i_version) then lets call it that: > > stx_modification_count. It's clear and unambiguous as to what it > > represents, especially as this counter is more than just a "data > > modification" counter - inode metadata modifications will also > > cause it to change.... > > I disagree that it's unambiguous. It works like mtime, right? > More like ctime + mtime mashed together. > Which wouldn't be of use for certain filesystems. An example of this would be > AFS, where it's incremented by 1 each time a write is committed, but is not > updated for metadata changes. This is what matters for data caching. > No. Basically the rules are that if something in the inode data or metadata changed, then it must be a "larger" value (also accounting for wraparound). So you also need to change it (usually by incrementing it) when doing namespace changes that involve it (renames, unlinks, etc.). > > > (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. > > > Note that the Linux IOC flags are a mess and filesystems such as Ext4 > > > define flags that aren't in linux/fs.h, so translation in the kernel > > > may be a necessity (or, possibly, we provide the filesystem type too). > > > > And we now also have FS_IOC_FSGETXATTR that extends the flags > > and information userspace can get from filesystems. It makes little > > sense to now add xstat() and not add everything this interface > > also exports... > > I'm not sure I agree. Stuff like extent sizes and extent hint flags seem like > very specialised things that don't belong in the stat interface. The project > ID, on the other hand is arguably a good thing to include. But we can always > add this later. > Yes. The entire point of this interface is that it is extendable. I'm all for simplicity here and just adding the bare minimum of fields to get the new interface in. The main thing we must do here though is to ID anything that would hobble us from being able to add new attributes later. Adding new fields in later piecemeal patches allows us to demonstrate that that concept actually works. > Note that are also two variants of the fsxattr struct defined in the kernel - > though one is a superset of the other. > > > > Time fields are split into separate seconds and nanoseconds fields to make > > > packing easier and the granularities can be queried with the filesystem > > > info system call. Note that times will be negative if before 1970; in such > > > a case, the nanosecond fields will also be negative if not zero. > > > > So what happens in ten years time when we want to support > > femptosecond resolution in the timestamp interface? We've got to > > change everything to 64 bit? Shouldn't we just make everything > > timestamp related 64 bit? > > You really think we're going to have accurate timestamps with a resolution of > a millionth of a nanosecond? This means you're going to be doing a 64-bit > division every time you want a nanosecond timestamp. > > Also, violet light has a period of ~1.2fs so your 1fs oscillator might emit UV > radiation. > Could contemporary machines get away with just shifting down by 32 bits? > > > The bits defined in the stx_attributes field convey information about a > > > file, how it is accessed, where it is and what it does. The following > > > attributes map to FS_*_FL flags and are the same numerical value: > > > > Please isolate the new interface flags completely from the FS_*_FL > > values. We should not repeat the mistake of tying values derived > > from filesystem specific on-disk values to a user interface. > > Why shouldn't I make a numerical correspondance with at least one set of such > flags? I get to define a whole new numberspace and can pick the values I > want. I see no particular reason to pick explicitly non-corresponding values > where possible. > > Now, I can agree that the code should say, for example: > > if (ext4->flag & FS_COMPRESSED_FL) > statx.attr |= STATX_ATTR_COMPRESSED; > if (ext4->flag & FS_ENCRYPTED_FL) > statx.attr |= STATX_ATTR_ENCRYPTED; > if (ext4->flag & FS_IMMUTABLE_FL) > statx.attr |= STATX_ATTR_IMMUTABLE; > ... > > and that the *compiler* should collapse this to: > > statx.attr |= ext4->flag & mask; > > but see: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78317 > > David > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Jeff Layton <jlayton@poochiereds.net> wrote: > > We've already been through that. I wanted to call it stx_data_version but > > that got argued down to stx_version. The problem is that what the version > > number means is entirely filesystem dependent, and it might not just reflect > > changes in the data. > > > > It had better not just reflect data changes. > > knfsd populates the NFSv4 change attribute from inode->i_version. It > _must_ have changed between subsequent queries if either the data or > metadata has changed (basically whenever you would update either the > ctime or the mtime). No, I think it *should* just reflect the data changes - otherwise you have have to burn your cached data unnecessarily. > > > So if stx_version this is intended to export the internal filesystem > > > inode change counter (i.e. inode->i_version) then lets call it that: > > > stx_modification_count. It's clear and unambiguous as to what it > > > represents, especially as this counter is more than just a "data > > > modification" counter - inode metadata modifications will also > > > cause it to change.... > > > > I disagree that it's unambiguous. It works like mtime, right? > > More like ctime + mtime mashed together. Isn't ctime updated every time mtime is? In which case stx_change_count would be a better name. > > Which wouldn't be of use for certain filesystems. An example of this > > would be AFS, where it's incremented by 1 each time a write is committed, > > but is not updated for metadata changes. This is what matters for data > > caching. > > > > No. Basically the rules are that if something in the inode data or > metadata changed, then it must be a "larger" value (also accounting for > wraparound). So you also need to change it (usually by incrementing it) > when doing namespace changes that involve it (renames, unlinks, etc.). That's entirely filesystem dependent. A better rule is that if you do a write and then compare the data version you got back to the version you had before; if it's increased by exactly one, there were no other writes between your last retrieval of the attributes and your write that just got committed. Admittedly, this assumes that the server serialises writes to a particular file. If the value just increases, you don't know that didn't happen by this mechanism, so the version is of limited value. > Adding new fields in later piecemeal patches allows us to demonstrate > that that concept actually works. You're probably right, but the downside is that we really need some way to find out what's supported. On the other hand, we probably need that anyway, hence my suggestion of an fsinfo() syscall also. > > You really think we're going to have accurate timestamps with a resolution > > of a millionth of a nanosecond? This means you're going to be doing a > > 64-bit division every time you want a nanosecond timestamp. > ... > > Could contemporary machines get away with just shifting down by 32 > bits? A better way would probably be to have: struct timestamp { __u64 seconds; __u32 nanoseconds; __u32 femtoseconds; }; where you effectively add all the fields together with appropriate multipliers. But I still wonder if we really are going to move to femtosecond timestamps, given that that's going to involve clock frequencies well in excess of 1 THz to be useful. Even attoseconds is probably unnecessary, given that clock frequencies don't seem to be moving much beyond a few GHz, though it's reasonable that we could have a timestamp counter that has an attosecond period - it's just that the processing time to deal with it seems likely to render it unnecessary. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2016-11-18 at 18:04 +0000, David Howells wrote: > Jeff Layton <jlayton@poochiereds.net> wrote: > > > > We've already been through that. I wanted to call it stx_data_version but > > > that got argued down to stx_version. The problem is that what the version > > > number means is entirely filesystem dependent, and it might not just reflect > > > changes in the data. > > > > > > > It had better not just reflect data changes. > > > > knfsd populates the NFSv4 change attribute from inode->i_version. It > > _must_ have changed between subsequent queries if either the data or > > metadata has changed (basically whenever you would update either the > > ctime or the mtime). > > No, I think it *should* just reflect the data changes - otherwise you have > have to burn your cached data unnecessarily. > > > > > So if stx_version this is intended to export the internal filesystem > > > > inode change counter (i.e. inode->i_version) then lets call it that: > > > > stx_modification_count. It's clear and unambiguous as to what it > > > > represents, especially as this counter is more than just a "data > > > > modification" counter - inode metadata modifications will also > > > > cause it to change.... > > > > > > I disagree that it's unambiguous. It works like mtime, right? > > > > More like ctime + mtime mashed together. > > Isn't ctime updated every time mtime is? In which case stx_change_count would > be a better name. > > > > Which wouldn't be of use for certain filesystems. An example of this > > > would be AFS, where it's incremented by 1 each time a write is committed, > > > but is not updated for metadata changes. This is what matters for data > > > caching. > > > > > > > No. Basically the rules are that if something in the inode data or > > metadata changed, then it must be a "larger" value (also accounting for > > wraparound). So you also need to change it (usually by incrementing it) > > when doing namespace changes that involve it (renames, unlinks, etc.). > > That's entirely filesystem dependent. > My mistake. I had thought that i_version was only used for NFSv4, and a few internal callers (particularly, some readdir implementations). I didn't realize that AFS also uses it. > A better rule is that if you do a write and then compare the data version you > got back to the version you had before; if it's increased by exactly one, > there were no other writes between your last retrieval of the attributes and > your write that just got committed. Admittedly, this assumes that the server > serialises writes to a particular file. > > If the value just increases, you don't know that didn't happen by this > mechanism, so the version is of limited value. > For the case of NFSv4, you can't infer that anyway. The protocol pretty much states that the client has to treat this value as semi-opaque. It can't infer anything other than "something has changed" (though it can look to see if a change attribute is "old" and discard it). Does AFS allow you to infer something from the actual value? Now that I realize that AFS has very different semantics, we might want to step back for a bit on presenting i_version to userspace. I think we need to come to some agreement on what i_version should actually mean before we expose it to userland to use. Maybe we should consider separate stx_change_attr and stx_data_change_attr fields in here? > > Adding new fields in later piecemeal patches allows us to demonstrate > > that that concept actually works. > > You're probably right, but the downside is that we really need some way to > find out what's supported. On the other hand, we probably need that anyway, > hence my suggestion of an fsinfo() syscall also. > Yeah, I think we will need an fsinfo call of some sort eventually. Alternately, we could just add the fields of interest to statx so that the callers can just query for it with the other fields (e.g. STATX_TS_GRANULARITY). Just document those attributes as being per- mount or whatever. > > > You really think we're going to have accurate timestamps with a resolution > > > of a millionth of a nanosecond? This means you're going to be doing a > > > 64-bit division every time you want a nanosecond timestamp. > > > > ... > > > > Could contemporary machines get away with just shifting down by 32 > > bits? > > A better way would probably be to have: > > struct timestamp { > __u64 seconds; > __u32 nanoseconds; > __u32 femtoseconds; > }; > > where you effectively add all the fields together with appropriate > multipliers. > Harder for those femtosecond scale machines to deal with, but maybe you're right. If the plan is to do that then we can just punt that out until that need arises, and add stx_?time_fsec fields at that point. The ugliness would all be hidden behind the glibc wrapper anyway (in principle). > But I still wonder if we really are going to move to femtosecond timestamps, > given that that's going to involve clock frequencies well in excess of 1 THz > to be useful. Even attoseconds is probably unnecessary, given that clock > frequencies don't seem to be moving much beyond a few GHz, though it's > reasonable that we could have a timestamp counter that has an attosecond > period - it's just that the processing time to deal with it seems likely to > render it unnecessary. > > David True, and we have to figure here that these are _file_ times, so you'd have to have file updates happening on sub-nanosecond timescales for this to make sense as well. I don't think we really need to add this now, especially if we can add the extra fields if/when the need ever arises.
Jeff Layton <jlayton@redhat.com> wrote:
> Does AFS allow you to infer something from the actual value?
Yes. Given:
(1) Each write on a file is atomic with respect to all other writes to that
same file.
(2) The data version is incremented by exactly one for each write committed,
and that value is returned in the reply to the write RPC call.
If you think you have a file with version 99, you do a call and get back
version 100, you *know* that there was no conflicting write before your write.
If the version came back as 101, however, you *know* that there was a write
you didn't know about. Therefore, you have to flush your cache.
David
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On Fri, Nov 18, 2016 at 10:29:04AM +0000, David Howells wrote: > Dave Chinner <david@fromorbit.com> wrote: > > > > (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. > > > Note that the Linux IOC flags are a mess and filesystems such as Ext4 > > > define flags that aren't in linux/fs.h, so translation in the kernel > > > may be a necessity (or, possibly, we provide the filesystem type too). > > > > And we now also have FS_IOC_FSGETXATTR that extends the flags > > and information userspace can get from filesystems. > > Btw, can you point me at the manpage that defines the fsxattr struct and its > flags? man xfsctl is the original source. However, .... > Also, ioctl_list(2) should probably include FS_IOC_FS[GS]ETXATTR. ... I thought patches had been sent to Michael to document them at the VFS ioctl level. maybe I confused it with something else..... Cheers, Dave.
On Fri, Nov 18, 2016 at 09:43:38AM +0000, David Howells wrote: > Dave Chinner <david@fromorbit.com> wrote: > > > Fields in struct statx come in a number of classes: > > > > > > (0) stx_dev_*, stx_blksize. > > > > > > These are local system information and are always available. > > > > What does stx_blksize actually mean? It's completely ambiguous in > > stat() because we don't actually report the physical block size > > here - we report the "minimum unit of efficient IO" that we expect > > applications to use. Please define :P > > Definition: "Same as struct stat::st_blksize". So it is still defined as "mostly useless", then? :/ > > > The following test program can be used to test the statx system call: > > > > > > samples/statx/test-statx.c > > > > > > Just compile and run, passing it paths to the files you want to examine. > > > The file is built automatically if CONFIG_SAMPLES is enabled. > > > > Can we get xfstests written to exercise and validate all this > > functionality, please? I'd suggest that adding xfs_io support for > > the statx syscall would be far more useful for xfstests than a > > standalone test program, too. We already have equivalent stat() > > functionality in xfs_io and that's used quite a bit in xfstests.... > > Feel free to write some! ;-) No, not my job. It is the responsibility of the person added new functionality to write the validity tests for everyone else to use. > But I need a simple standalone test program to be able to test what I write, > and I've no inclination to wheel out huge testsuites for an interface that > people are still arguing about and wanting changed. The test suite should be developed concurrently with the code. You know, best software engineering practices and all that. Just a small example: Darrick landed 100+ reflink related tests in xfstests before we merged the XFS reflink functionality. And that's just for XFS - this is something that /all filesystems/ need to work correctly with, so it's even more important that we have tests to verify functionality /before/ it gets merged. Quite frankly, I think this has to be an unconditional requirement for such generic, expandabled new syscall functionality - either we get test coverage for it before merge, or we don't merge it. We've demonstrated time and time again that shit doesn't work if it's not tested and cannot be widely verified by independent filesystem developers. Again, I'll use the example of Darrick's reflink tests - that exposed multiple bugs in the btrfs reflink implementation that nobody knew existed because /they'd never been tested/. And we've found several subtle differences in fs implementations that would seriously confuse applications (e.g. how a range of "0 bytes" is treated by the filesystem) as a result of adding tests to exercise these exact semantics. These are the sorts of issues we need test coverage to avoid, and we need it before merge, not after. Cheers, Dave. > > David >
Dave Chinner <david@fromorbit.com> wrote: > > Btw, can you point me at the manpage that defines the fsxattr struct and its > > flags? > > man xfsctl is the original source. However, .... warthog>man xfsctl No manual entry for xfsctl This should be in the kernel manpages repo since it's kernel UAPI. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Nov 17, 2016 at 08:28:57PM -0700, Andreas Dilger wrote: > On Nov 17, 2016, at 4:40 PM, Dave Chinner <david@fromorbit.com> wrote: > >> > >> Time fields are split into separate seconds and nanoseconds fields to make > >> packing easier and the granularities can be queried with the filesystem > >> info system call. Note that times will be negative if before 1970; in > >> such a case, the nanosecond fields will also be negative if not zero. > > > > So what happens in ten years time when we want to support > > femptosecond resolution in the timestamp interface? We've got to > > change everything to 64 bit? Shouldn't we just make everything > > timestamp related 64 bit? > > Is this a serious request? Are we going to need to multiply everything > by 10e9 to convert to/from nanoseconds for the next 10 years on the off > chance that we have timestamps more accurate than this in the future? We've been stuck with the stat() interface since, what, the early 1980s? And it will still be used in 10-15 years time. That's a /50-year lifetime/ for a syscall interface. So it's not unreasonable to think that statx() might have a similar lifetime. statx() is clearly intended to support >y2038 dates cleanly, so clearly we're intending statx() to still be around in 20-25 years. And when we start thinking in those timeframes, an increase in timestamp resoultion of at least another 10e-3 is likely.... > > Please isolate the new interface flags completely from the FS_*_FL > > values. We should not repeat the mistake of tying values derived > > from filesystem specific on-disk values to a user interface. > > Using the existing FS_*_FL flags as initial values is not worse than > starting with any other arbitrary values for the flags. Except it starts with a sparse set of flags for no good reason. Someone comes along needed to add a new flag and wonders WTF there are holes in the flags space, and whether it is because flags have been removed and whether it's unsafe to use the flag space in the holes... New user facing APIs should be clean and neat and not carry any unnecessary historical baggage with them.... > >> STATX_ATTR_NONUNIX_OWNERSHIP File doesn't have Unixy ownership > >> STATX_ATTR_HAS_ACL File has an ACL > > > > So statx will require us to do ACL lookups? i.e. instead of just > > reading the inode to get the information, we'll also have to do > > extended attribute lookups? That's potentially very expensive if > > the extended attribute is not stored in the inode.... > > No, there is no requirement to return anything that the caller didn't > ask for. Applications are going to use STATX_ALL because it's simpler than specifying 10 different flags on every statx() call and then checking them on return. i.e. the set/check feature flags API sounds good until you have to write the boiler plate code it requires time you want to stat a file... Cheers, Dave.
On Fri, Nov 18, 2016 at 09:48:21PM +0000, David Howells wrote: > Dave Chinner <david@fromorbit.com> wrote: > > > > Btw, can you point me at the manpage that defines the fsxattr struct and its > > > flags? > > > > man xfsctl is the original source. However, .... > > warthog>man xfsctl > No manual entry for xfsctl > > This should be in the kernel manpages repo since it's kernel UAPI. "original source" is where the API came from - that's XFS_IOC_FSGETXATTR - and xfsctl from xfsprogs is where that was documented. That page documents a bunch of other XFS specific ioctls, too, so it is appropriately located. Like I said, I thought patches had been sent to Michael to lift the FS_IOC_FSGETXATTR documentation from this page into the official linux man pages package. If not, that can be chased up separately, but the XFS ioctl man page certainly does not belong there. Cheers, Dave.
Dave Chinner <david@fromorbit.com> wrote: > > Definition: "Same as struct stat::st_blksize". > > So it is still defined as "mostly useless", then? :/ If we're going to be able to emulate stat() with this, then st_blksize must be determinable from whatever's in struct statx. If you can provide something better for stx_blksize and an algorithm for mapping that to st_blksize, then please do so. > The test suite should be developed concurrently with the code. You > know, best software engineering practices and all that. Just a small > example: Darrick landed 100+ reflink related tests in xfstests > before we merged the XFS reflink functionality. I can't give you tests to merge yet. Given the amount of bikeshedding that's taken place on this, I'm glad I *haven't* done the testsuite yet - it would have much more than doubled the amount of work. I *still* don't know what the final form is going to be. I've chucked out almost everything extra because every bit has someone who argues with it - and this includes people who argue against things that have to be there! Further: warthog>ls xfstests-dev/doc CHANGES The documentation is missing. There's a bit in the top level README, but there's a whole lot of information that *should* be there - and isn't. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Dave Chinner <david@fromorbit.com> wrote: > And when we start thinking in those timeframes, an > increase in timestamp resoultion of at least another 10e-3 is > likely.... Is it, though? To be useful, surely you have to be able to jam quite a few instructions into a 1ns block, including memory accesses. Rather than providing: struct timestamp { __s64 seconds; __s64 femtoseconds; }; which would require 64-bit divisions to get nanosecond timestamps that we do actually use, I would lean towards: struct timestamp { __s64 seconds; __s32 nanoseconds; __s32 femtoseconds; }; where the fields are, in effect, additive. Which means I could represent this as: __s64 stx_atime_s; /* Last access time */ __s64 stx_btime_s; /* File creation time */ __s64 stx_ctime_s; /* Last attribute change time */ __s64 stx_mtime_s; /* Last data modification time */ __s32 stx_atime_ns; /* Last access time (ns part) */ __s32 stx_btime_ns; /* File creation time (ns part) */ __s32 stx_ctime_ns; /* Last attribute change time (ns part) */ __s32 stx_mtime_ns; /* Last data modification time (ns part) */ and then add: __s32 stx_atime_fs; /* Last access time (fs part) */ __s32 stx_btime_fs; /* File creation time (fs part) */ __s32 stx_ctime_fs; /* Last attribute change time (fs part) */ __s32 stx_mtime_fs; /* Last data modification time (fs part) */ later. If we *really* do want to allow for atto- or femto- second resolution timestamps (and you've still not entirely convinced me that it's going to be necessary - the speed of signal propagation still has an ungetroundable limit), then we could stick the space in now - but I think it's likely to remain dead space. Maybe we should switch to Windows-style timestamp resolution: struct timestamp { __s64 hundred_ns; /* Time in 100ns increments */ __s32 femtoseconds; /* Additional fs component */ }; > > Using the existing FS_*_FL flags as initial values is not worse than > > starting with any other arbitrary values for the flags. > > Except it starts with a sparse set of flags for no good reason. Actually, a very good reason. You can map those flags, on ext4 at least, with a load, an AND and an OR. Three instructions[*]. If the bits don't correspond, it gets more expensive (4-5 instructions per bit + 1). [*] Leastways, it *should* be three instructions, but gcc fails to optimise it correctly. I have a bz logged for this. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Dave, [Best to CC me when I'm mentioned in the discussion. I only caught this by chance.] On 18 November 2016 at 23:17, Dave Chinner <david@fromorbit.com> wrote: > On Fri, Nov 18, 2016 at 09:48:21PM +0000, David Howells wrote: >> Dave Chinner <david@fromorbit.com> wrote: >> >> > > Btw, can you point me at the manpage that defines the fsxattr struct and its >> > > flags? >> > >> > man xfsctl is the original source. However, .... >> >> warthog>man xfsctl >> No manual entry for xfsctl >> >> This should be in the kernel manpages repo since it's kernel UAPI. > > "original source" is where the API came from - that's > XFS_IOC_FSGETXATTR - and xfsctl from xfsprogs is where that was > documented. That page documents a bunch of other XFS specific > ioctls, too, so it is appropriately located. > > Like I said, I thought patches had been sent to Michael to lift the > FS_IOC_FSGETXATTR documentation from this page into the official > linux man pages package. If not, that can be chased up separately, > but the XFS ioctl man page certainly does not belong there. No patches for FS_IOC_FSGETXATTR documentation came to man-pages, as far as I know. I'll be happy to take them. Cheers, Michael
On Fri, Nov 18, 2016 at 10:54:02PM +0000, David Howells wrote: > Dave Chinner <david@fromorbit.com> wrote: > > > And when we start thinking in those timeframes, an > > increase in timestamp resoultion of at least another 10e-3 is > > likely.... > > Is it, though? To be useful, surely you have to be able to jam quite a few > instructions into a 1ns block, including memory accesses. > > Rather than providing: > > struct timestamp { > __s64 seconds; > __s64 femtoseconds; > }; > > which would require 64-bit divisions to get nanosecond timestamps that we do > actually use, I would lean towards: > > struct timestamp { > __s64 seconds; > __s32 nanoseconds; > __s32 femtoseconds; > }; No. Just provide a 64 bit high resoultion field, and define it to contain nanoseconds. When we need higher resolution to be exported to userspace, we use a /feature flag/ to indicate that is contains something like attoseconds or the like. This also gives userspace a method of choosing the resolution it wants..... > __s32 stx_btime_ns; /* File creation time (ns part) */ > __s32 stx_ctime_ns; /* Last attribute change time (ns part) */ > __s32 stx_mtime_ns; /* Last data modification time (ns part) */ > > and then add: > > __s32 stx_atime_fs; /* Last access time (fs part) */ > __s32 stx_btime_fs; /* File creation time (fs part) */ > __s32 stx_ctime_fs; /* Last attribute change time (fs part) */ > __s32 stx_mtime_fs; /* Last data modification time (fs part) */ > > later. Which burns a significant part of the spare space in the structure. > If we *really* do want to allow for atto- or femto- second resolution > timestamps (and you've still not entirely convinced me that it's going to be > necessary - the speed of signal propagation still has an ungetroundable > limit), then we could stick the space in now - but I think it's likely to > remain dead space. We don't really care if the strucuture 250 bytes or 300 bytes, it's not going to have any significant impact on memory usage or performance. We should just suck it up now and future proof the timestamp interface, as history has proven repeatedly that we suck as making our time/timestamp interfaces future proof.... > > > Using the existing FS_*_FL flags as initial values is not worse than > > > starting with any other arbitrary values for the flags. > > > > Except it starts with a sparse set of flags for no good reason. > > Actually, a very good reason. You can map those flags, on ext4 at least, with > a load, an AND and an OR. Three instructions[*]. If the bits don't > correspond, it gets more expensive (4-5 instructions per bit + 1). Two words: premature optimisation. Every other filesystem has to map their own internal flags to the user interface flags, so why should we make the user interface harder to understand and maintain just to allow a special snowflake optimisation for /only one filesystem/? There's a worse problem than that, though - we can't add certain flags to the userspace API because the /conflict with ext4 on-disk flags/ that aren't exported to userspace and so to work around that we have this shitty hack to define what parts of the flag space contain flags that the userspace API can interact with: #define FS_FL_USER_VISIBLE 0x0003DFFF /* User visible flags */ #define FS_FL_USER_MODIFIABLE 0x000380FF /* User modifiable flags */ These mask out the ext2/3/4 flags that should not be visible to userspace and/or not be modifiable by userspace. Having to maintain crap like this is a direct result of exporting on-disk flag values to userspace APIs. *Let's not repeat the mistakes of the past* in new interfaces. Cheers, Dave. > > [*] Leastways, it *should* be three instructions, but gcc fails to optimise it > correctly. I have a bz logged for this. > > David >
> > increase in timestamp resoultion of at least another 10e-3 is > > likely.... > > Is it, though? To be useful, surely you have to be able to jam quite a few > instructions into a 1ns block, including memory accesses. > > Rather than providing: > > struct timestamp { > __s64 seconds; > __s64 femtoseconds; > }; > > which would require 64-bit divisions to get nanosecond timestamps that we do > actually use, I would lean towards: > > struct timestamp { > __s64 seconds; > __s32 nanoseconds; > __s32 femtoseconds; > }; Which gets silly. The nanosecond world is defined by the speed of light. Short of someone finding a way to change that digital computing as we know it today is going to be living in the nanoseconds world. You hit the point of 'can't measure the difference' before you hit the point of 'can usefully order things using' Alan -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Nov 21, 2016 at 02:30:13PM +0000, One Thousand Gnomes wrote: > > > increase in timestamp resoultion of at least another 10e-3 is > > > likely.... > > > > Is it, though? To be useful, surely you have to be able to jam quite a few > > instructions into a 1ns block, including memory accesses. > > > > Rather than providing: > > > > struct timestamp { > > __s64 seconds; > > __s64 femtoseconds; > > }; > > > > which would require 64-bit divisions to get nanosecond timestamps that we do > > actually use, I would lean towards: > > > > struct timestamp { > > __s64 seconds; > > __s32 nanoseconds; > > __s32 femtoseconds; > > }; > > Which gets silly. The nanosecond world is defined by the speed of light. > Short of someone finding a way to change that digital computing as we > know it today is going to be living in the nanoseconds world. You hit the > point of 'can't measure the difference' before you hit the point of 'can > usefully order things using' We already have clock rates that are fractions of a nanosecond per cycle. We have pmem storage here right now that is accessed at the speed of the CPU - actual nanosecond resolution timestamp capability is a reality at the bleeding edge of storage technology right now. It doesn't take much vision to extend the current hardare capabilities with coherent hardware accelerators (e.g. as has been added to the Power platform) writing directly into pmem storage and providing higher resolution timestamps than the CPU can generate. Call me silly if you want - I don't care - but let's not ignore the emerging storage technology trends that are there for everyone to see... Cheers, Dave.
Dave Chinner <david@fromorbit.com> wrote: > No. Just provide a 64 bit high resoultion field, and define it to > contain nanoseconds. When we need higher resolution to be exported > to userspace, we use a /feature flag/ to indicate that is contains > something like attoseconds or the like. That sounds suspiciously like a bad idea - if you're talking about a flag with a currently undefined meaning that the kernel can inflict on userspace without warning to change the meaning of the nanoseconds field to something we haven't defined yet. Userspace would have to ask for it. David -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2016-11-22 at 10:39 +0000, David Howells wrote: > Dave Chinner <david@fromorbit.com> wrote: > > > > > No. Just provide a 64 bit high resoultion field, and define it to > > contain nanoseconds. When we need higher resolution to be exported > > to userspace, we use a /feature flag/ to indicate that is contains > > something like attoseconds or the like. > > That sounds suspiciously like a bad idea - if you're talking about a flag with > a currently undefined meaning that the kernel can inflict on userspace without > warning to change the meaning of the nanoseconds field to something we haven't > defined yet. > > Userspace would have to ask for it. > Agreed. I think the best thing would be to simply plan to add new femtoseconds fields in the struct if/when it becomes needed. We can easily hide the ugliness of the fields not being adjacent to the rest of the timestamp behind the femtosecond resolution glibc API that will also be needed. If we're worried about space utilization, then let's pad the struct out by 4 extra 32-bit fields in advance of that. Again, a major design point of statx is that it is to be extendable. I don't see any reason that we need to do this now.
On Tue, Nov 22, 2016 at 10:39:29AM +0000, David Howells wrote: > Dave Chinner <david@fromorbit.com> wrote: > > > No. Just provide a 64 bit high resoultion field, and define it to > > contain nanoseconds. When we need higher resolution to be exported > > to userspace, we use a /feature flag/ to indicate that is contains > > something like attoseconds or the like. > > That sounds suspiciously like a bad idea - if you're talking about a flag with > a currently undefined meaning that the kernel can inflict on userspace without > warning to change the meaning of the nanoseconds field to something we haven't > defined yet. > > Userspace would have to ask for it. Yes, of course it would - this would enable userspace to move from struct timespec to something with higher resolution without having to use different structures or guess what the resolution being returned by the kernel is for different filesystems, We had a major mess with the time_t -> struct timespec upgrade of the stat() kernel interface to support nanosecond timestamps in the syscall because when stat() was first designed all those years ago single second resolution was all anyone needed. The original designers of the stat API didn't have 30+ years of history telling them that machines will get faster than anyone could imagine and that timestamps will always get more accurate and increase in resolution. Perhaps people are fine with repeating past mistakes - all I can do is point them out and suggest alternative approaches that will avoid a repeat... Cheers, Dave.
========
OVERVIEW
========
The idea was initially proposed as a set of xattrs that could be retrieved
with getxattr(), but the general preferance proved to be for a new syscall
with an extended stat structure.
This has a number of uses:
(1) Better support for the y2038 problem [Arnd Bergmann].
(2) Creation time: The SMB protocol carries the creation time, which could
be exported by Samba, which will in turn help CIFS make use of
FS-Cache as that can be used for coherency data.
This is also specified in NFSv4 as a recommended attribute and could
be exported by NFSD [Steve French].
(3) Lightweight stat: Ask for just those details of interest, and allow a
netfs (such as NFS) to approximate anything not of interest, possibly
without going to the server [Trond Myklebust, Ulrich Drepper, Andreas
Dilger].
(4) Heavyweight stat: Force a netfs to go to the server, even if it thinks
its cached attributes are up to date [Trond Myklebust].
(5) Data version number: Could be used by userspace NFS servers [Aneesh
Kumar].
Can also be used to modify fill_post_wcc() in NFSD which retrieves
i_version directly, but has just called vfs_getattr(). It could get
it from the kstat struct if it used vfs_xgetattr() instead.
(6) BSD stat compatibility: Including more fields from the BSD stat such
as creation time (st_btime) and inode generation number (st_gen)
[Jeremy Allison, Bernd Schubert].
(7) Inode generation number: Useful for FUSE and userspace NFS servers
[Bernd Schubert]. This was asked for but later deemed unnecessary
with the open-by-handle capability available
(8) Extra coherency data may be useful in making backups [Andreas Dilger].
(9) Allow the filesystem to indicate what it can/cannot provide: A
filesystem can now say it doesn't support a standard stat feature if
that isn't available, so if, for instance, inode numbers or UIDs don't
exist or are fabricated locally...
(10) Make the fields a consistent size on all arches and make them large.
(11) Store a 16-byte volume ID in the superblock that can be returned in
struct xstat [Steve French].
(12) Include granularity fields in the time data to indicate the
granularity of each of the times (NFSv4 time_delta) [Steve French].
(13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags.
Note that the Linux IOC flags are a mess and filesystems such as Ext4
define flags that aren't in linux/fs.h, so translation in the kernel
may be a necessity (or, possibly, we provide the filesystem type too).
(14) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
Michael Kerrisk].
(15) Spare space, request flags and information flags are provided for
future expansion.
Note that not all of the above are implemented here.
===============
NEW SYSTEM CALL
===============
The new system call is:
int ret = statx(int dfd,
const char *filename,
unsigned int flags,
unsigned int mask,
struct statx *buffer);
The dfd, filename and flags parameters indicate the file to query. There
is no equivalent of lstat() as that can be emulated with statx() by passing
AT_SYMLINK_NOFOLLOW in flags. There is also no equivalent of fstat() as
that can be emulated by passing a NULL filename to statx() with the fd of
interest in dfd.
AT_STATX_FORCE_SYNC can be set in flags. This will require a network
filesystem to synchronise its attributes with the server.
AT_STATX_DONT_SYNC can be set in flags. This will suppress synchronisation
with the server in a network filesystem. The resulting values should be
considered approximate.
If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for
stat() on that filesystem.
mask is a bitmask indicating the fields in struct statx that are of
interest to the caller. The user should set this to STATX_BASIC_STATS to
get the basic set returned by stat(). It should be note that asking for
more information may entail more I/O operations.
buffer points to the destination for the data. This must be 256 bytes in
size.
======================
MAIN ATTRIBUTES RECORD
======================
The following structures are defined in which to return the main attribute
set:
struct statx {
__u32 stx_mask;
__u32 stx_blksize;
__u64 stx_attributes;
__u32 stx_nlink;
__u32 stx_uid;
__u32 stx_gid;
__u16 stx_mode;
__u16 __spare0[1];
__u64 stx_ino;
__u64 stx_size;
__u64 stx_blocks;
__u64 stx_version;
__s64 stx_atime;
__s64 stx_btime;
__s64 stx_ctime;
__s64 stx_mtime;
__s32 stx_atime_ns;
__s32 stx_btime_ns;
__s32 stx_ctime_ns;
__s32 stx_mtime_ns;
__u32 stx_rdev_major;
__u32 stx_rdev_minor;
__u32 stx_dev_major;
__u32 stx_dev_minor;
__u64 __spare1[16];
};
The defined bits in request_mask and stx_mask are:
STATX_TYPE Want/got stx_mode & S_IFMT
STATX_MODE Want/got stx_mode & ~S_IFMT
STATX_NLINK Want/got stx_nlink
STATX_UID Want/got stx_uid
STATX_GID Want/got stx_gid
STATX_ATIME Want/got stx_atime{,_ns}
STATX_MTIME Want/got stx_mtime{,_ns}
STATX_CTIME Want/got stx_ctime{,_ns}
STATX_INO Want/got stx_ino
STATX_SIZE Want/got stx_size
STATX_BLOCKS Want/got stx_blocks
STATX_BASIC_STATS [The stuff in the normal stat struct]
STATX_BTIME Want/got stx_btime{,_ns}
STATX_VERSION Want/got stx_version
STATX_ALL [All currently available stuff]
stx_btime is the file creation time; stx_version is the data version number
(i_version); stx_mask is a bitmask indicating the data provided; and
__spares*[] are where as-yet undefined fields can be placed.
Time fields are split into separate seconds and nanoseconds fields to make
packing easier and the granularities can be queried with the filesystem
info system call. Note that times will be negative if before 1970; in such
a case, the nanosecond fields will also be negative if not zero.
The bits defined in the stx_attributes field convey information about a
file, how it is accessed, where it is and what it does. The following
attributes map to FS_*_FL flags and are the same numerical value:
STATX_ATTR_COMPRESSED File is compressed by the fs
STATX_ATTR_IMMUTABLE File is marked immutable
STATX_ATTR_APPEND File is append-only
STATX_ATTR_NODUMP File is not to be dumped
STATX_ATTR_ENCRYPTED File requires key to decrypt in fs
The supported flags are listed by:
STATX_ATTR_FS_IOC_FLAGS
[Are any other IOC flags of sufficient general interest to be exposed
through this interface?]
New flags include:
STATX_ATTR_NONUNIX_OWNERSHIP File doesn't have Unixy ownership
STATX_ATTR_HAS_ACL File has an ACL
STATX_ATTR_KERNEL_API File is kernel API (eg: procfs/sysfs)
STATX_ATTR_REMOTE File is remote and needs network
STATX_ATTR_FABRICATED File was made up by fs
STATX_ATTR_AUTOMOUNT Object is an automount trigger
STATX_ATTR_UNLISTED_DENTS Dir: Lookup may find files getdents doesn't
These are for the use of GUI tools that might want to mark files specially,
depending on what they are.
Fields in struct statx come in a number of classes:
(0) stx_dev_*, stx_blksize.
These are local system information and are always available.
(1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time*, stx_ino,
stx_size, stx_blocks.
These will be returned whether the caller asks for them or not. The
corresponding bits in stx_mask will be set to indicate whether they
actually have valid values.
If the caller didn't ask for them, then they may be approximated. For
example, NFS won't waste any time updating them from the server,
unless as a byproduct of updating something requested.
If the values don't actually exist for the underlying object (such as
UID or GID on a DOS file), then the bit won't be set in the stx_mask,
even if the caller asked for the value. In such a case, the returned
value will be a fabrication.
Note that there are instances where the type might not be valid, for
instance Windows reparse points.
(2) stx_rdev_*.
This will be set only if stx_mode indicates we're looking at a
blockdev or a chardev, otherwise will be 0.
(3) stx_btime*, stx_version.
Similar to (1), except these will be set to 0 if they don't exist.
=======
TESTING
=======
The following test program can be used to test the statx system call:
samples/statx/test-statx.c
Just compile and run, passing it paths to the files you want to examine.
The file is built automatically if CONFIG_SAMPLES is enabled.
Here's some example output. Firstly, an NFS directory that crosses to
another FSID. Note that the FABRICATED and AUTOMOUNT info flags are set.
The former because the directory is invented locally as we don't see the
underlying dir on the server, the latter because transiting this directory
will cause d_automount to be invoked by the VFS.
[root@andromeda tmp]# ./samples/statx/test-statx -A /warthog/data
statx(/warthog/data) = 0
results=17ff
Size: 4096 Blocks: 8 IO Block: 1048576 directory
Device: 00:26 Inode: 1703937 Links: 124
Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041
Access: 2016-11-10 15:52:11.219935864+0000
Modify: 2016-11-10 08:07:32.482314928+0000
Change: 2016-11-10 08:07:32.482314928+0000
Data version: 58242ac41cbf8ab0h
Attributes: 000000000000e000 (-------- -------- -------- -------- -------- -------- mfr----- --------)
IO-blocksize: blksize=1048576
Secondly, the result of automounting on that directory.
[root@andromeda tmp]# ./samples/statx/test-statx /warthog/data
statx(/warthog/data) = 0
results=17ff
Size: 4096 Blocks: 8 IO Block: 1048576 directory
Device: 00:27 Inode: 2 Links: 124
Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041
Access: 2016-11-10 15:52:11.219935864+0000
Modify: 2016-11-10 08:07:32.482314928+0000
Change: 2016-11-10 08:07:32.482314928+0000
Data version: 58242ac41cbf8ab0h
Attributes: 0000000000002000 (-------- -------- -------- -------- -------- -------- --r----- --------)
IO-blocksize: blksize=1048576
Signed-off-by: David Howells <dhowells@redhat.com>
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/exportfs/expfs.c | 4
fs/stat.c | 294 +++++++++++++++++++++++++++++---
include/linux/fs.h | 5 -
include/linux/stat.h | 19 +-
include/linux/syscalls.h | 3
include/uapi/linux/fcntl.h | 2
include/uapi/linux/stat.h | 124 +++++++++++++
samples/Kconfig | 5 +
samples/Makefile | 3
samples/statx/Makefile | 10 +
samples/statx/test-statx.c | 248 +++++++++++++++++++++++++++
13 files changed, 679 insertions(+), 40 deletions(-)
create mode 100644 samples/statx/Makefile
create mode 100644 samples/statx/test-statx.c
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 2b3618542544..9ba050fe47f3 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -389,3 +389,4 @@
380 i386 pkey_mprotect sys_pkey_mprotect
381 i386 pkey_alloc sys_pkey_alloc
382 i386 pkey_free sys_pkey_free
+383 i386 statx sys_statx
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index e93ef0b38db8..5aef183e2f85 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -338,6 +338,7 @@
329 common pkey_mprotect sys_pkey_mprotect
330 common pkey_alloc sys_pkey_alloc
331 common pkey_free sys_pkey_free
+332 common statx sys_statx
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index a4b531be9168..2acc31751248 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -299,7 +299,9 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
* filesystem supports 64-bit inode numbers. So we need to
* actually call ->getattr, not just read i_ino:
*/
- error = vfs_getattr_nosec(&child_path, &stat);
+ stat.query_flags = 0;
+ stat.request_mask = STATX_BASIC_STATS;
+ error = vfs_xgetattr_nosec(&child_path, &stat);
if (error)
return error;
buffer.ino = stat.ino;
diff --git a/fs/stat.c b/fs/stat.c
index bc045c7994e1..78c0a5086038 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -18,6 +18,15 @@
#include <asm/uaccess.h>
#include <asm/unistd.h>
+/**
+ * generic_fillattr - Fill in the basic attributes from the inode struct
+ * @inode: Inode to use as the source
+ * @stat: Where to fill in the attributes
+ *
+ * Fill in the basic attributes in the kstat structure from data that's to be
+ * found on the VFS inode structure. This is the default if no getattr inode
+ * operation is supplied.
+ */
void generic_fillattr(struct inode *inode, struct kstat *stat)
{
stat->dev = inode->i_sb->s_dev;
@@ -27,87 +36,189 @@ void generic_fillattr(struct inode *inode, struct kstat *stat)
stat->uid = inode->i_uid;
stat->gid = inode->i_gid;
stat->rdev = inode->i_rdev;
- stat->size = i_size_read(inode);
- stat->atime = inode->i_atime;
stat->mtime = inode->i_mtime;
stat->ctime = inode->i_ctime;
- stat->blksize = (1 << inode->i_blkbits);
+ stat->size = i_size_read(inode);
stat->blocks = inode->i_blocks;
-}
+ stat->blksize = 1 << inode->i_blkbits;
+ stat->result_mask |= STATX_BASIC_STATS;
+ if (IS_NOATIME(inode))
+ stat->result_mask &= ~STATX_ATIME;
+ else
+ stat->atime = inode->i_atime;
+
+ if (IS_AUTOMOUNT(inode))
+ stat->attributes |= STATX_ATTR_AUTOMOUNT;
+}
EXPORT_SYMBOL(generic_fillattr);
/**
- * vfs_getattr_nosec - getattr without security checks
+ * vfs_xgetattr_nosec - getattr without security checks
* @path: file to get attributes from
* @stat: structure to return attributes in
*
* Get attributes without calling security_inode_getattr.
*
- * Currently the only caller other than vfs_getattr is internal to the
- * filehandle lookup code, which uses only the inode number and returns
- * no attributes to any user. Any other code probably wants
- * vfs_getattr.
+ * Currently the only caller other than vfs_xgetattr is internal to the
+ * filehandle lookup code, which uses only the inode number and returns no
+ * attributes to any user. Any other code probably wants vfs_xgetattr.
+ *
+ * The caller must set stat->request_mask to indicate what they want and
+ * stat->query_flags to indicate whether the server should be queried.
*/
-int vfs_getattr_nosec(struct path *path, struct kstat *stat)
+int vfs_xgetattr_nosec(struct path *path, struct kstat *stat)
{
struct inode *inode = d_backing_inode(path->dentry);
+ stat->query_flags &= ~KSTAT_QUERY_FLAGS;
+
+ stat->result_mask = 0;
+ stat->attributes = 0;
if (inode->i_op->getattr)
return inode->i_op->getattr(path->mnt, path->dentry, stat);
generic_fillattr(inode, stat);
return 0;
}
+EXPORT_SYMBOL(vfs_xgetattr_nosec);
-EXPORT_SYMBOL(vfs_getattr_nosec);
-
-int vfs_getattr(struct path *path, struct kstat *stat)
+/*
+ * vfs_xgetattr - Get the enhanced basic attributes of a file
+ * @path: The file of interest
+ * @stat: Where to return the statistics
+ *
+ * Ask the filesystem for a file's attributes. The caller must have preset
+ * stat->request_mask and stat->query_flags to indicate what they want.
+ *
+ * If the file is remote, the filesystem can be forced to update the attributes
+ * from the backing store by passing AT_FORCE_ATTR_SYNC in query_flags or can
+ * suppress the update by passing AT_NO_ATTR_SYNC.
+ *
+ * Bits must have been set in stat->request_mask to indicate which attributes
+ * the caller wants retrieving. Any such attribute not requested may be
+ * returned anyway, but the value may be approximate, and, if remote, may not
+ * have been synchronised with the server.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_xgetattr(struct path *path, struct kstat *stat)
{
int retval;
retval = security_inode_getattr(path);
if (retval)
return retval;
- return vfs_getattr_nosec(path, stat);
+ return vfs_xgetattr_nosec(path, stat);
}
+EXPORT_SYMBOL(vfs_xgetattr);
+/**
+ * vfs_getattr - Get the basic attributes of a file
+ * @path: The file of interest
+ * @stat: Where to return the statistics
+ *
+ * Ask the filesystem for a file's attributes. If remote, the filesystem isn't
+ * forced to update its files from the backing store. Only the basic set of
+ * attributes will be retrieved; anyone wanting more must use vfs_xgetattr(),
+ * as must anyone who wants to force attributes to be sync'd with the server.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_getattr(struct path *path, struct kstat *stat)
+{
+ stat->query_flags = 0;
+ stat->request_mask = STATX_BASIC_STATS;
+ return vfs_xgetattr(path, stat);
+}
EXPORT_SYMBOL(vfs_getattr);
-int vfs_fstat(unsigned int fd, struct kstat *stat)
+/**
+ * vfs_fstatx - Get the enhanced basic attributes by file descriptor
+ * @fd: The file descriptor referring to the file of interest
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_xgetattr(). The main difference is
+ * that it uses a file descriptor to determine the file location.
+ *
+ * The caller must have preset stat->query_flags and stat->request_mask as for
+ * vfs_xgetattr().
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_fstatx(unsigned int fd, struct kstat *stat)
{
struct fd f = fdget_raw(fd);
int error = -EBADF;
if (f.file) {
- error = vfs_getattr(&f.file->f_path, stat);
+ error = vfs_xgetattr(&f.file->f_path, stat);
fdput(f);
}
return error;
}
+EXPORT_SYMBOL(vfs_fstatx);
+
+/**
+ * vfs_fstat - Get basic attributes by file descriptor
+ * @fd: The file descriptor referring to the file of interest
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_getattr(). The main difference is
+ * that it uses a file descriptor to determine the file location.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_fstat(unsigned int fd, struct kstat *stat)
+{
+ stat->query_flags = 0;
+ stat->request_mask = STATX_BASIC_STATS;
+ return vfs_fstatx(fd, stat);
+}
EXPORT_SYMBOL(vfs_fstat);
-int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
- int flag)
+/**
+ * vfs_statx - Get basic and extra attributes by filename
+ * @dfd: A file descriptor representing the base dir for a relative filename
+ * @filename: The name of the file of interest
+ * @flags: Flags to control the query
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_xgetattr(). The main difference is
+ * that it uses a filename and base directory to determine the file location.
+ * Additionally, the addition of AT_SYMLINK_NOFOLLOW to flags will prevent a
+ * symlink at the given name from being referenced.
+ *
+ * The caller must have preset stat->request_mask as for vfs_xgetattr(). The
+ * flags are also used to load up stat->query_flags.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_statx(int dfd, const char __user *filename, int flags,
+ struct kstat *stat)
{
struct path path;
int error = -EINVAL;
- unsigned int lookup_flags = 0;
+ unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
- if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
- AT_EMPTY_PATH)) != 0)
- goto out;
+ if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
+ AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
+ return -EINVAL;
- if (!(flag & AT_SYMLINK_NOFOLLOW))
- lookup_flags |= LOOKUP_FOLLOW;
- if (flag & AT_EMPTY_PATH)
+ if (flags & AT_SYMLINK_NOFOLLOW)
+ lookup_flags &= ~LOOKUP_FOLLOW;
+ if (flags & AT_NO_AUTOMOUNT)
+ lookup_flags &= ~LOOKUP_AUTOMOUNT;
+ if (flags & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
+ stat->query_flags = flags;
+
retry:
error = user_path_at(dfd, filename, lookup_flags, &path);
if (error)
goto out;
- error = vfs_getattr(&path, stat);
+ error = vfs_xgetattr(&path, stat);
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
@@ -116,17 +227,65 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
out:
return error;
}
+EXPORT_SYMBOL(vfs_statx);
+
+/**
+ * vfs_fstatat - Get basic attributes by filename
+ * @dfd: A file descriptor representing the base dir for a relative filename
+ * @filename: The name of the file of interest
+ * @flags: Flags to control the query
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_statx(). The difference is that it
+ * preselects basic stats only. The flags are used to load up
+ * stat->query_flags in addition to indicating symlink handling during path
+ * resolution.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
+ int flags)
+{
+ stat->request_mask = STATX_BASIC_STATS;
+ return vfs_statx(dfd, filename, flags, stat);
+}
EXPORT_SYMBOL(vfs_fstatat);
-int vfs_stat(const char __user *name, struct kstat *stat)
+/**
+ * vfs_stat - Get basic attributes by filename
+ * @filename: The name of the file of interest
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_statx(). The difference is that it
+ * preselects basic stats only, terminal symlinks are followed regardless and a
+ * remote filesystem can't be forced to query the server. If such is desired,
+ * vfs_statx() should be used instead.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_stat(const char __user *filename, struct kstat *stat)
{
- return vfs_fstatat(AT_FDCWD, name, stat, 0);
+ stat->request_mask = STATX_BASIC_STATS;
+ return vfs_statx(AT_FDCWD, filename, 0, stat);
}
EXPORT_SYMBOL(vfs_stat);
+/**
+ * vfs_lstat - Get basic attrs by filename, without following terminal symlink
+ * @filename: The name of the file of interest
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_statx(). The difference is that it
+ * preselects basic stats only, terminal symlinks are note followed regardless
+ * and a remote filesystem can't be forced to query the server. If such is
+ * desired, vfs_statx() should be used instead.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
int vfs_lstat(const char __user *name, struct kstat *stat)
{
- return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
+ stat->request_mask = STATX_BASIC_STATS;
+ return vfs_statx(AT_FDCWD, name, AT_SYMLINK_NOFOLLOW, stat);
}
EXPORT_SYMBOL(vfs_lstat);
@@ -141,7 +300,7 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta
{
static int warncount = 5;
struct __old_kernel_stat tmp;
-
+
if (warncount > 0) {
warncount--;
printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
@@ -166,7 +325,7 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta
#if BITS_PER_LONG == 32
if (stat->size > MAX_NON_LFS)
return -EOVERFLOW;
-#endif
+#endif
tmp.st_size = stat->size;
tmp.st_atime = stat->atime.tv_sec;
tmp.st_mtime = stat->mtime.tv_sec;
@@ -443,6 +602,79 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
}
#endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
+/*
+ * Set the statx results.
+ */
+static long statx_set_result(struct kstat *stat, struct statx __user *buffer)
+{
+ uid_t uid = from_kuid_munged(current_user_ns(), stat->uid);
+ gid_t gid = from_kgid_munged(current_user_ns(), stat->gid);
+
+#define __put_timestamp(kts, uts) ( \
+ __put_user(kts.tv_sec, uts##_s ) || \
+ __put_user(kts.tv_nsec, uts##_ns ))
+
+ if (__put_user(stat->result_mask, &buffer->stx_mask ) ||
+ __put_user(stat->mode, &buffer->stx_mode ) ||
+ __clear_user(&buffer->__spare0, sizeof(buffer->__spare0)) ||
+ __put_user(stat->nlink, &buffer->stx_nlink ) ||
+ __put_user(uid, &buffer->stx_uid ) ||
+ __put_user(gid, &buffer->stx_gid ) ||
+ __put_user(stat->attributes, &buffer->stx_attributes ) ||
+ __put_user(stat->blksize, &buffer->stx_blksize ) ||
+ __put_user(MAJOR(stat->rdev), &buffer->stx_rdev_major ) ||
+ __put_user(MINOR(stat->rdev), &buffer->stx_rdev_minor ) ||
+ __put_user(MAJOR(stat->dev), &buffer->stx_dev_major ) ||
+ __put_user(MINOR(stat->dev), &buffer->stx_dev_minor ) ||
+ __put_timestamp(stat->atime, &buffer->stx_atime ) ||
+ __put_timestamp(stat->btime, &buffer->stx_btime ) ||
+ __put_timestamp(stat->ctime, &buffer->stx_ctime ) ||
+ __put_timestamp(stat->mtime, &buffer->stx_mtime ) ||
+ __put_user(stat->ino, &buffer->stx_ino ) ||
+ __put_user(stat->size, &buffer->stx_size ) ||
+ __put_user(stat->blocks, &buffer->stx_blocks ) ||
+ __put_user(stat->version, &buffer->stx_version ) ||
+ __clear_user(&buffer->__spare1, sizeof(buffer->__spare1)))
+ return -EFAULT;
+
+ return 0;
+}
+
+/**
+ * sys_statx - System call to get enhanced stats
+ * @dfd: Base directory to pathwalk from *or* fd to stat.
+ * @filename: File to stat *or* NULL.
+ * @flags: AT_* flags to control pathwalk.
+ * @mask: Parts of statx struct actually required.
+ * @buffer: Result buffer.
+ *
+ * Note that if filename is NULL, then it does the equivalent of fstat() using
+ * dfd to indicate the file of interest.
+ */
+SYSCALL_DEFINE5(statx,
+ int, dfd, const char __user *, filename, unsigned, flags,
+ unsigned int, mask,
+ struct statx __user *, buffer)
+{
+ struct kstat stat;
+ int error;
+
+ if (!access_ok(VERIFY_WRITE, buffer, sizeof(*buffer)))
+ return -EFAULT;
+
+ memset(&stat, 0, sizeof(stat));
+ stat.query_flags = flags;
+ stat.request_mask = mask & STATX_ALL;
+
+ if (filename)
+ error = vfs_statx(dfd, filename, flags, &stat);
+ else
+ error = vfs_fstatx(dfd, &stat);
+ if (error)
+ return error;
+ return statx_set_result(&stat, buffer);
+}
+
/* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
void __inode_add_bytes(struct inode *inode, loff_t bytes)
{
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 16d2b6e874d6..f153199566b4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2916,8 +2916,9 @@ extern const struct inode_operations page_symlink_inode_operations;
extern void kfree_link(void *);
extern int generic_readlink(struct dentry *, char __user *, int);
extern void generic_fillattr(struct inode *, struct kstat *);
-int vfs_getattr_nosec(struct path *path, struct kstat *stat);
+extern int vfs_xgetattr_nosec(struct path *path, struct kstat *stat);
extern int vfs_getattr(struct path *, struct kstat *);
+extern int vfs_xgetattr(struct path *, struct kstat *);
void __inode_add_bytes(struct inode *inode, loff_t bytes);
void inode_add_bytes(struct inode *inode, loff_t bytes);
void __inode_sub_bytes(struct inode *inode, loff_t bytes);
@@ -2935,6 +2936,8 @@ extern int vfs_lstat(const char __user *, struct kstat *);
extern int vfs_fstat(unsigned int, struct kstat *);
extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
+extern int vfs_xstat(int, const char __user *, int, struct kstat *);
+extern int vfs_xfstat(unsigned int, struct kstat *);
extern int __generic_block_fiemap(struct inode *inode,
struct fiemap_extent_info *fieinfo,
diff --git a/include/linux/stat.h b/include/linux/stat.h
index 075cb0c7eb2a..cf25bb5cf754 100644
--- a/include/linux/stat.h
+++ b/include/linux/stat.h
@@ -19,19 +19,26 @@
#include <linux/uidgid.h>
struct kstat {
- u64 ino;
- dev_t dev;
+ u32 query_flags; /* Operational flags */
+#define KSTAT_QUERY_FLAGS (AT_STATX_FORCE_SYNC | AT_STATX_DONT_SYNC)
+ u32 request_mask; /* What fields the user asked for */
+ u32 result_mask; /* What fields the user got */
umode_t mode;
unsigned int nlink;
+ uint32_t blksize; /* Preferred I/O size */
+ u64 attributes;
+ u64 ino;
+ dev_t dev;
+ dev_t rdev;
kuid_t uid;
kgid_t gid;
- dev_t rdev;
loff_t size;
- struct timespec atime;
+ struct timespec atime;
struct timespec mtime;
struct timespec ctime;
- unsigned long blksize;
- unsigned long long blocks;
+ struct timespec btime; /* File creation time */
+ u64 blocks;
+ u64 version; /* Data version */
};
#endif
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 91a740f6b884..980c3c9b06f8 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -48,6 +48,7 @@ struct stat;
struct stat64;
struct statfs;
struct statfs64;
+struct statx;
struct __sysctl_args;
struct sysinfo;
struct timespec;
@@ -902,5 +903,7 @@ asmlinkage long sys_pkey_mprotect(unsigned long start, size_t len,
unsigned long prot, int pkey);
asmlinkage long sys_pkey_alloc(unsigned long flags, unsigned long init_val);
asmlinkage long sys_pkey_free(int pkey);
+asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
+ unsigned mask, struct statx __user *buffer);
#endif
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index beed138bd359..c49cb6edaafa 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -62,6 +62,8 @@
#define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */
#define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */
#define AT_EMPTY_PATH 0x1000 /* Allow empty relative pathname */
+#define AT_STATX_FORCE_SYNC 0x2000 /* Force the attributes to be sync'd with the server */
+#define AT_STATX_DONT_SYNC 0x4000 /* Don't sync attributes with the server */
#endif /* _UAPI_LINUX_FCNTL_H */
diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
index 7fec7e36d921..32ea14c1c960 100644
--- a/include/uapi/linux/stat.h
+++ b/include/uapi/linux/stat.h
@@ -1,6 +1,7 @@
#ifndef _UAPI_LINUX_STAT_H
#define _UAPI_LINUX_STAT_H
+#include <linux/types.h>
#if defined(__KERNEL__) || !defined(__GLIBC__) || (__GLIBC__ < 2)
@@ -41,5 +42,128 @@
#endif
+/*
+ * Structures for the extended file attribute retrieval system call
+ * (statx()).
+ *
+ * The caller passes a mask of what they're specifically interested in as a
+ * parameter to statx(). What statx() actually got will be indicated in
+ * st_mask upon return.
+ *
+ * For each bit in the mask argument:
+ *
+ * - if the datum is not supported:
+ *
+ * - the bit will be cleared, and
+ *
+ * - the datum will be set to an appropriate fabricated value if one is
+ * available (eg. CIFS can take a default uid and gid), otherwise
+ *
+ * - the field will be cleared;
+ *
+ * - otherwise, if explicitly requested:
+ *
+ * - the datum will be synchronised to the server if AT_STATX_FORCE_SYNC is
+ * set or if the datum is considered out of date, and
+ *
+ * - the field will be filled in and the bit will be set;
+ *
+ * - otherwise, if not requested, but available in approximate form without any
+ * effort, it will be filled in anyway, and the bit will be set upon return
+ * (it might not be up to date, however, and no attempt will be made to
+ * synchronise the internal state first);
+ *
+ * - otherwise the field and the bit will be cleared before returning.
+ *
+ * Items in STATX_BASIC_STATS may be marked unavailable on return, but they
+ * will have values installed for compatibility purposes so that stat() and
+ * co. can be emulated in userspace.
+ */
+struct statx {
+ /* 0x00 */
+ __u32 stx_mask; /* What results were written [uncond] */
+ __u32 stx_blksize; /* Preferred general I/O size [uncond] */
+ __u64 stx_attributes; /* Flags conveying information about the file [uncond] */
+ /* 0x10 */
+ __u32 stx_nlink; /* Number of hard links */
+ __u32 stx_uid; /* User ID of owner */
+ __u32 stx_gid; /* Group ID of owner */
+ __u16 stx_mode; /* File mode */
+ __u16 __spare0[1];
+ /* 0x20 */
+ __u64 stx_ino; /* Inode number */
+ __u64 stx_size; /* File size */
+ __u64 stx_blocks; /* Number of 512-byte blocks allocated */
+ __u64 stx_version; /* Data version number */
+ /* 0x40 */
+ __s64 stx_atime_s; /* Last access time */
+ __s64 stx_btime_s; /* File creation time */
+ __s64 stx_ctime_s; /* Last attribute change time */
+ __s64 stx_mtime_s; /* Last data modification time */
+ /* 0x60 */
+ __s32 stx_atime_ns; /* Last access time (ns part) */
+ __s32 stx_btime_ns; /* File creation time (ns part) */
+ __s32 stx_ctime_ns; /* Last attribute change time (ns part) */
+ __s32 stx_mtime_ns; /* Last data modification time (ns part) */
+ /* 0x70 */
+ __u32 stx_rdev_major; /* Device ID of special file [if bdev/cdev] */
+ __u32 stx_rdev_minor;
+ __u32 stx_dev_major; /* ID of device containing file [uncond] */
+ __u32 stx_dev_minor;
+ /* 0x80 */
+ __u64 __spare1[16]; /* Spare space for future expansion */
+ /* 0x100 */
+};
+
+/*
+ * Flags to be stx_mask
+ *
+ * Query request/result mask for statx() and struct statx::stx_mask.
+ *
+ * These bits should be set in the mask argument of statx() to request
+ * particular items when calling statx().
+ */
+#define STATX_TYPE 0x00000001U /* Want/got stx_mode & S_IFMT */
+#define STATX_MODE 0x00000002U /* Want/got stx_mode & ~S_IFMT */
+#define STATX_NLINK 0x00000004U /* Want/got stx_nlink */
+#define STATX_UID 0x00000008U /* Want/got stx_uid */
+#define STATX_GID 0x00000010U /* Want/got stx_gid */
+#define STATX_ATIME 0x00000020U /* Want/got stx_atime */
+#define STATX_MTIME 0x00000040U /* Want/got stx_mtime */
+#define STATX_CTIME 0x00000080U /* Want/got stx_ctime */
+#define STATX_INO 0x00000100U /* Want/got stx_ino */
+#define STATX_SIZE 0x00000200U /* Want/got stx_size */
+#define STATX_BLOCKS 0x00000400U /* Want/got stx_blocks */
+#define STATX_BASIC_STATS 0x000007ffU /* The stuff in the normal stat struct */
+#define STATX_BTIME 0x00000800U /* Want/got stx_btime */
+#define STATX_VERSION 0x00001000U /* Want/got stx_version */
+#define STATX_ALL 0x00001fffU /* All currently supported flags */
+
+/*
+ * Attributes to be found in stx_attributes
+ *
+ * These give information about the features or the state of a file that might
+ * be of use to ordinary userspace programs such as GUIs or ls rather than
+ * specialised tools.
+ *
+ * Note that the flags marked [I] correspond to generic FS_IOC_FLAGS
+ * semantically. Where possible, the numerical value is picked to correspond
+ * also.
+ */
+#define STATX_ATTR_COMPRESSED 0x00000004 /* [I] File is compressed by the fs */
+#define STATX_ATTR_IMMUTABLE 0x00000010 /* [I] File is marked immutable */
+#define STATX_ATTR_APPEND 0x00000020 /* [I] File is append-only */
+#define STATX_ATTR_NODUMP 0x00000040 /* [I] File is not to be dumped */
+#define STATX_ATTR_NONUNIX_OWNERSHIP 0x00000100 /* File has non-Unix ownership details */
+#define STATX_ATTR_HAS_ACL 0x00000200 /* File has an ACL */
+#define STATX_ATTR_ENCRYPTED 0x00000800 /* [I] File requires key to decrypt in fs */
+#define STATX_ATTR_FS_IOC_FLAGS 0x00000874 /* Attrs corresponding to FS_*_FL flags */
+
+#define STATX_ATTR_KERNEL_API 0x00001000 /* File is kernel API (eg: procfs/sysfs) */
+#define STATX_ATTR_REMOTE 0x00002000 /* File is remote and needs network */
+#define STATX_ATTR_FABRICATED 0x00004000 /* File was made up by fs and is transient */
+#define STATX_ATTR_AUTOMOUNT 0x00008000 /* Dir: Automount trigger */
+#define STATX_ATTR_UNLISTED_DENTS 0x00010000 /* Dir: Lookup may find files getdents doesn't */
+
#endif /* _UAPI_LINUX_STAT_H */
diff --git a/samples/Kconfig b/samples/Kconfig
index a6d2a43bbf2e..94a7488f14ae 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -105,4 +105,9 @@ config SAMPLE_BLACKFIN_GPTIMERS
help
Build samples of blackfin gptimers sample module.
+config SAMPLE_STATX
+ bool "Build example extended-stat using code"
+ help
+ Build example userspace program to use the new extended-stat syscall.
+
endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index e17d66d77f09..8eeb15e13413 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -2,4 +2,5 @@
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \
hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
- configfs/ connector/ v4l/ trace_printk/ blackfin/
+ configfs/ connector/ v4l/ trace_printk/ blackfin/ \
+ statx/
diff --git a/samples/statx/Makefile b/samples/statx/Makefile
new file mode 100644
index 000000000000..1f80a3d8cf45
--- /dev/null
+++ b/samples/statx/Makefile
@@ -0,0 +1,10 @@
+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-$(CONFIG_SAMPLE_STATX) := test-statx
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
diff --git a/samples/statx/test-statx.c b/samples/statx/test-statx.c
new file mode 100644
index 000000000000..2419b33fc15d
--- /dev/null
+++ b/samples/statx/test-statx.c
@@ -0,0 +1,248 @@
+/* Test the statx() system call
+ *
+ * Copyright (C) 2015 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define _GNU_SOURCE
+#define _ATFILE_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <time.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <linux/stat.h>
+#include <linux/fcntl.h>
+#include <sys/stat.h>
+
+#define AT_STATX_FORCE_SYNC 0x2000
+#define AT_STATX_DONT_SYNC 0x4000
+
+static __attribute__((unused))
+ssize_t statx(int dfd, const char *filename, unsigned flags,
+ unsigned int mask, struct statx *buffer)
+{
+ return syscall(__NR_statx, dfd, filename, flags, mask, buffer);
+}
+
+static void print_time(const char *field, __s64 tv_sec, __s32 tv_nsec)
+{
+ struct tm tm;
+ time_t tim;
+ char buffer[100];
+ int len;
+
+ tim = tv_sec;
+ if (!localtime_r(&tim, &tm)) {
+ perror("localtime_r");
+ exit(1);
+ }
+ len = strftime(buffer, 100, "%F %T", &tm);
+ if (len == 0) {
+ perror("strftime");
+ exit(1);
+ }
+ printf("%s", field);
+ fwrite(buffer, 1, len, stdout);
+ printf(".%09u", tv_nsec);
+ len = strftime(buffer, 100, "%z", &tm);
+ if (len == 0) {
+ perror("strftime2");
+ exit(1);
+ }
+ fwrite(buffer, 1, len, stdout);
+ printf("\n");
+}
+
+static void dump_statx(struct statx *stx)
+{
+ char buffer[256], ft = '?';
+
+ printf("results=%x\n", stx->stx_mask);
+
+ printf(" ");
+ if (stx->stx_mask & STATX_SIZE)
+ printf(" Size: %-15llu", (unsigned long long)stx->stx_size);
+ if (stx->stx_mask & STATX_BLOCKS)
+ printf(" Blocks: %-10llu", (unsigned long long)stx->stx_blocks);
+ printf(" IO Block: %-6llu ", (unsigned long long)stx->stx_blksize);
+ if (stx->stx_mask & STATX_MODE) {
+ switch (stx->stx_mode & S_IFMT) {
+ case S_IFIFO: printf(" FIFO\n"); ft = 'p'; break;
+ case S_IFCHR: printf(" character special file\n"); ft = 'c'; break;
+ case S_IFDIR: printf(" directory\n"); ft = 'd'; break;
+ case S_IFBLK: printf(" block special file\n"); ft = 'b'; break;
+ case S_IFREG: printf(" regular file\n"); ft = '-'; break;
+ case S_IFLNK: printf(" symbolic link\n"); ft = 'l'; break;
+ case S_IFSOCK: printf(" socket\n"); ft = 's'; break;
+ default:
+ printf("unknown type (%o)\n", stx->stx_mode & S_IFMT);
+ break;
+ }
+ }
+
+ sprintf(buffer, "%02x:%02x", stx->stx_dev_major, stx->stx_dev_minor);
+ printf("Device: %-15s", buffer);
+ if (stx->stx_mask & STATX_INO)
+ printf(" Inode: %-11llu", (unsigned long long) stx->stx_ino);
+ if (stx->stx_mask & STATX_SIZE)
+ printf(" Links: %-5u", stx->stx_nlink);
+ switch (stx->stx_mask & STATX_MODE) {
+ case S_IFBLK:
+ case S_IFCHR:
+ printf(" Device type: %u,%u", stx->stx_rdev_major, stx->stx_rdev_minor);
+ break;
+ }
+ printf("\n");
+
+ if (stx->stx_mask & STATX_MODE)
+ printf("Access: (%04o/%c%c%c%c%c%c%c%c%c%c) ",
+ stx->stx_mode & 07777,
+ ft,
+ stx->stx_mode & S_IRUSR ? 'r' : '-',
+ stx->stx_mode & S_IWUSR ? 'w' : '-',
+ stx->stx_mode & S_IXUSR ? 'x' : '-',
+ stx->stx_mode & S_IRGRP ? 'r' : '-',
+ stx->stx_mode & S_IWGRP ? 'w' : '-',
+ stx->stx_mode & S_IXGRP ? 'x' : '-',
+ stx->stx_mode & S_IROTH ? 'r' : '-',
+ stx->stx_mode & S_IWOTH ? 'w' : '-',
+ stx->stx_mode & S_IXOTH ? 'x' : '-');
+ if (stx->stx_mask & STATX_UID)
+ printf("Uid: %5d ", stx->stx_uid);
+ if (stx->stx_mask & STATX_GID)
+ printf("Gid: %5d\n", stx->stx_gid);
+
+ if (stx->stx_mask & STATX_ATIME)
+ print_time("Access: ", stx->stx_atime_s, stx->stx_atime_ns);
+ if (stx->stx_mask & STATX_MTIME)
+ print_time("Modify: ", stx->stx_mtime_s, stx->stx_mtime_ns);
+ if (stx->stx_mask & STATX_CTIME)
+ print_time("Change: ", stx->stx_ctime_s, stx->stx_ctime_ns);
+ if (stx->stx_mask & STATX_BTIME)
+ print_time(" Birth: ", stx->stx_btime_s, stx->stx_btime_ns);
+
+ if (stx->stx_mask & STATX_VERSION)
+ printf("Data version: %llxh\n",
+ (unsigned long long)stx->stx_version);
+
+ if (stx->stx_attributes) {
+ unsigned char bits;
+ int loop, byte;
+
+ static char attr_representation[64 + 1] =
+ /* STATX_ATTR_ flags: */
+ "????????" /* 63-56 */
+ "????????" /* 55-48 */
+ "????????" /* 47-40 */
+ "????????" /* 39-32 */
+ "????????" /* 31-24 0x00000000-ff000000 */
+ "???????u" /* 23-16 0x00000000-00ff0000 */
+ "mfrke?AU" /* 15- 8 0x00000000-0000ff00 */
+ "?dai?c??" /* 7- 0 0x00000000-000000ff */
+ ;
+
+ printf("Attributes: %016llx (", stx->stx_attributes);
+ for (byte = 64 - 8; byte >= 0; byte -= 8) {
+ bits = stx->stx_attributes >> byte;
+ for (loop = 7; loop >= 0; loop--) {
+ int bit = byte + loop;
+
+ if (bits & 0x80)
+ putchar(attr_representation[63 - bit]);
+ else
+ putchar('-');
+ bits <<= 1;
+ }
+ if (byte)
+ putchar(' ');
+ }
+ printf(")\n");
+ }
+
+ printf("IO-blocksize: blksize=%u\n", stx->stx_blksize);
+}
+
+static void dump_hex(unsigned long long *data, int from, int to)
+{
+ unsigned offset, print_offset = 1, col = 0;
+
+ from /= 8;
+ to = (to + 7) / 8;
+
+ for (offset = from; offset < to; offset++) {
+ if (print_offset) {
+ printf("%04x: ", offset * 8);
+ print_offset = 0;
+ }
+ printf("%016llx", data[offset]);
+ col++;
+ if ((col & 3) == 0) {
+ printf("\n");
+ print_offset = 1;
+ } else {
+ printf(" ");
+ }
+ }
+
+ if (!print_offset)
+ printf("\n");
+}
+
+int main(int argc, char **argv)
+{
+ struct statx stx;
+ int ret, raw = 0, atflag = AT_SYMLINK_NOFOLLOW;
+
+ unsigned int mask = STATX_ALL;
+
+ for (argv++; *argv; argv++) {
+ if (strcmp(*argv, "-F") == 0) {
+ atflag |= AT_STATX_FORCE_SYNC;
+ continue;
+ }
+ if (strcmp(*argv, "-D") == 0) {
+ atflag |= AT_STATX_DONT_SYNC;
+ continue;
+ }
+ if (strcmp(*argv, "-L") == 0) {
+ atflag &= ~AT_SYMLINK_NOFOLLOW;
+ continue;
+ }
+ if (strcmp(*argv, "-O") == 0) {
+ mask &= ~STATX_BASIC_STATS;
+ continue;
+ }
+ if (strcmp(*argv, "-A") == 0) {
+ atflag |= AT_NO_AUTOMOUNT;
+ continue;
+ }
+ if (strcmp(*argv, "-R") == 0) {
+ raw = 1;
+ continue;
+ }
+
+ memset(&stx, 0xbf, sizeof(stx));
+ ret = statx(AT_FDCWD, *argv, atflag, mask, &stx);
+ printf("statx(%s) = %d\n", *argv, ret);
+ if (ret < 0) {
+ perror(*argv);
+ exit(1);
+ }
+
+ if (raw)
+ dump_hex((unsigned long long *)&stx, 0, sizeof(stx));
+
+ dump_statx(&stx);
+ }
+ return 0;
+}