| Message ID | 20170228145737.19016-6-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Feb 28, 2017 at 06:57:30AM -0800, Christoph Hellwig wrote: > This fcntl can be used to query I/O parameters for the given file > descriptor. Initially it is used for the I/O alignment and atomic > write parameters. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/fcntl.c | 18 ++++++++++++++++++ > include/linux/fs.h | 1 + > include/uapi/linux/fcntl.h | 16 ++++++++++++++++ > 3 files changed, 35 insertions(+) > > diff --git a/fs/fcntl.c b/fs/fcntl.c > index ca5d228be7ea..248fb4cc66a6 100644 > --- a/fs/fcntl.c > +++ b/fs/fcntl.c > @@ -241,6 +241,21 @@ static int f_getowner_uids(struct file *filp, unsigned long arg) > } > #endif > > +static int fcntl_ioinfo(struct file *file, void __user *argp) > +{ > + struct fcntl_ioinfo fio = { 0, }; > + > + if (file->f_op->ioinfo) { > + int ret = file->f_op->ioinfo(file, &fio); > + if (ret) > + return ret; > + } > + > + if (copy_to_user(argp, &fio, sizeof(fio))) > + return -EFAULT; > + return 0; > +} > + > static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, > struct file *filp) > { > @@ -335,6 +350,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, > case F_GET_SEALS: > err = shmem_fcntl(filp, cmd, arg); > break; > + case F_IOINFO: > + err = fcntl_ioinfo(filp, (void __user *)arg); > + break; > default: > break; > } > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 2ba074328894..33b08a8c2bc3 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1680,6 +1680,7 @@ struct file_operations { > u64); > ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *, > u64); > + int (*ioinfo)(struct file *, struct fcntl_ioinfo *); > }; > > struct inode_operations { > diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h > index beed138bd359..6b0aaba7c623 100644 > --- a/include/uapi/linux/fcntl.h > +++ b/include/uapi/linux/fcntl.h > @@ -42,6 +42,22 @@ > #define F_SEAL_WRITE 0x0008 /* prevent writes */ > /* (1U << 31) is reserved for signed error codes */ > > + > +#define F_IOINFO (F_LINUX_SPECIFIC_BASE + 11) > + > +struct fcntl_ioinfo { > + __u16 fio_flags; /* FIO_FL_* */ > + __u16 fio_alignment; /* required I/O alignment on disk */ Hm... is fio_alignment is specified in units of bytes? If so, then shouldn't this be a __u32 so that we can handle some weird future device that wants, say, 1MB alignment for its atomic IO? I'm not sure there /are/ such weird devices, and the current patchset assumes (probably sanely) that atomic requests only have to be lba-aligned, but otoh this is a userland field and we have plenty of reserved space. Though, now that I look at the XFS ioinfo patch, I guess fio_alignment is set only for O_DIRECT files? So it's really the required alignment for directio operations. (Now I think I'm simply confused about this field.) --D > + __u32 __reserved1; /* must be zero */ > + __u64 fio_max_atomic; /* max size for atomic writes */ > + __u64 __reserved2[14];/* must be zero */ > +}; > + > +/* supports atomic writes using O_(D)SYNC */ > +#define FIO_FL_ATOMIC_OSYNC (1 << 0) > +/* supports atomic writes committed using fsync/fdatasync/msync */ > +#define FIO_FL_ATOMIC_FSYNC (1 << 1) > + > /* > * Types of directory notifications that may be requested. > */ > -- > 2.11.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Feb 28, 2017 at 08:51:39AM -0800, Darrick J. Wong wrote: > Hm... is fio_alignment is specified in units of bytes? Yes. > If so, then > shouldn't this be a __u32 so that we can handle some weird future device > that wants, say, 1MB alignment for its atomic IO? That would be pretty useless. Anything bigger than sector / block size would not really be usable for typical applications. > Though, now that I look at the XFS ioinfo patch, I guess fio_alignment > is set only for O_DIRECT files? Yes. > So it's really the required alignment > for directio operations. For buffered I/O we can write at byte granularity and still use the atomic commits, but for direct I/O we can only COW at block size granularity.
diff --git a/fs/fcntl.c b/fs/fcntl.c index ca5d228be7ea..248fb4cc66a6 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -241,6 +241,21 @@ static int f_getowner_uids(struct file *filp, unsigned long arg) } #endif +static int fcntl_ioinfo(struct file *file, void __user *argp) +{ + struct fcntl_ioinfo fio = { 0, }; + + if (file->f_op->ioinfo) { + int ret = file->f_op->ioinfo(file, &fio); + if (ret) + return ret; + } + + if (copy_to_user(argp, &fio, sizeof(fio))) + return -EFAULT; + return 0; +} + static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, struct file *filp) { @@ -335,6 +350,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, case F_GET_SEALS: err = shmem_fcntl(filp, cmd, arg); break; + case F_IOINFO: + err = fcntl_ioinfo(filp, (void __user *)arg); + break; default: break; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 2ba074328894..33b08a8c2bc3 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1680,6 +1680,7 @@ struct file_operations { u64); ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *, u64); + int (*ioinfo)(struct file *, struct fcntl_ioinfo *); }; struct inode_operations { diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index beed138bd359..6b0aaba7c623 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -42,6 +42,22 @@ #define F_SEAL_WRITE 0x0008 /* prevent writes */ /* (1U << 31) is reserved for signed error codes */ + +#define F_IOINFO (F_LINUX_SPECIFIC_BASE + 11) + +struct fcntl_ioinfo { + __u16 fio_flags; /* FIO_FL_* */ + __u16 fio_alignment; /* required I/O alignment on disk */ + __u32 __reserved1; /* must be zero */ + __u64 fio_max_atomic; /* max size for atomic writes */ + __u64 __reserved2[14];/* must be zero */ +}; + +/* supports atomic writes using O_(D)SYNC */ +#define FIO_FL_ATOMIC_OSYNC (1 << 0) +/* supports atomic writes committed using fsync/fdatasync/msync */ +#define FIO_FL_ATOMIC_FSYNC (1 << 1) + /* * Types of directory notifications that may be requested. */
This fcntl can be used to query I/O parameters for the given file descriptor. Initially it is used for the I/O alignment and atomic write parameters. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/fcntl.c | 18 ++++++++++++++++++ include/linux/fs.h | 1 + include/uapi/linux/fcntl.h | 16 ++++++++++++++++ 3 files changed, 35 insertions(+)