| Message ID | 1441397823-1203-2-git-send-email-Anna.Schumaker@Netapp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Sep 04, 2015 at 04:16:55PM -0400, Anna Schumaker wrote: > From: Zach Brown <zab@redhat.com> > > Add a copy_file_range() system call for offloading copies between > regular files. > > This gives an interface to underlying layers of the storage stack which > can copy without reading and writing all the data. There are a few > candidates that should support copy offloading in the nearer term: > > - btrfs shares extent references with its clone ioctl > - NFS has patches to add a COPY command which copies on the server > - SCSI has a family of XCOPY commands which copy in the device > > This system call avoids the complexity of also accelerating the creation > of the destination file by operating on an existing destination file > descriptor, not a path. > > Currently the high level vfs entry point limits copy offloading to files > on the same mount and super (and not in the same file). This can be > relaxed if we get implementations which can copy between file systems > safely. > > Signed-off-by: Zach Brown <zab@redhat.com> > [Anna Schumaker: Change -EINVAL to -EBADF during file verification] > Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> > --- > fs/read_write.c | 129 ++++++++++++++++++++++++++++++++++++++ > include/linux/fs.h | 3 + > include/uapi/asm-generic/unistd.h | 4 +- > kernel/sys_ni.c | 1 + > 4 files changed, 136 insertions(+), 1 deletion(-) > > diff --git a/fs/read_write.c b/fs/read_write.c > index 819ef3f..82c4933 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -16,6 +16,7 @@ > #include <linux/pagemap.h> > #include <linux/splice.h> > #include <linux/compat.h> > +#include <linux/mount.h> > #include "internal.h" > > #include <asm/uaccess.h> > @@ -1327,3 +1328,131 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, > return do_sendfile(out_fd, in_fd, NULL, count, 0); > } > #endif > + > +/* > + * copy_file_range() differs from regular file read and write in that it > + * specifically allows return partial success. When it does so is up to > + * the copy_file_range method. > + */ > +ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > + struct file *file_out, loff_t pos_out, > + size_t len, int flags) > +{ > + struct inode *inode_in; > + struct inode *inode_out; > + ssize_t ret; > + > + if (flags) > + return -EINVAL; > + > + if (len == 0) > + return 0; > + > + /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */ > + ret = rw_verify_area(READ, file_in, &pos_in, len); > + if (ret >= 0) > + ret = rw_verify_area(WRITE, file_out, &pos_out, len); > + if (ret < 0) > + return ret; > + > + if (!(file_in->f_mode & FMODE_READ) || > + !(file_out->f_mode & FMODE_WRITE) || > + (file_out->f_flags & O_APPEND) || > + !file_in->f_op || !file_in->f_op->copy_file_range) > + return -EBADF; > + > + inode_in = file_inode(file_in); > + inode_out = file_inode(file_out); > + > + /* make sure offsets don't wrap and the input is inside i_size */ > + if (pos_in + len < pos_in || pos_out + len < pos_out || > + pos_in + len > i_size_read(inode_in)) > + return -EINVAL; > + > + /* this could be relaxed once a method supports cross-fs copies */ > + if (inode_in->i_sb != inode_out->i_sb || > + file_in->f_path.mnt != file_out->f_path.mnt) > + return -EXDEV; > + > + /* forbid ranges in the same file */ > + if (inode_in == inode_out) > + return -EINVAL; btrfs does and XFS will support the case of a file sharing blocks with itself. --D > + > + ret = mnt_want_write_file(file_out); > + if (ret) > + return ret; > + > + ret = file_in->f_op->copy_file_range(file_in, pos_in, file_out, pos_out, > + len, flags); > + if (ret > 0) { > + fsnotify_access(file_in); > + add_rchar(current, ret); > + fsnotify_modify(file_out); > + add_wchar(current, ret); > + } > + inc_syscr(current); > + inc_syscw(current); > + > + mnt_drop_write_file(file_out); > + > + return ret; > +} > +EXPORT_SYMBOL(vfs_copy_file_range); > + > +SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in, > + int, fd_out, loff_t __user *, off_out, > + size_t, len, unsigned int, flags) > +{ > + loff_t pos_in; > + loff_t pos_out; > + struct fd f_in; > + struct fd f_out; > + ssize_t ret; > + > + f_in = fdget(fd_in); > + f_out = fdget(fd_out); > + if (!f_in.file || !f_out.file) { > + ret = -EBADF; > + goto out; > + } > + > + ret = -EFAULT; > + if (off_in) { > + if (copy_from_user(&pos_in, off_in, sizeof(loff_t))) > + goto out; > + } else { > + pos_in = f_in.file->f_pos; > + } > + > + if (off_out) { > + if (copy_from_user(&pos_out, off_out, sizeof(loff_t))) > + goto out; > + } else { > + pos_out = f_out.file->f_pos; > + } > + > + ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len, > + flags); > + if (ret > 0) { > + pos_in += ret; > + pos_out += ret; > + > + if (off_in) { > + if (copy_to_user(off_in, &pos_in, sizeof(loff_t))) > + ret = -EFAULT; > + } else { > + f_in.file->f_pos = pos_in; > + } > + > + if (off_out) { > + if (copy_to_user(off_out, &pos_out, sizeof(loff_t))) > + ret = -EFAULT; > + } else { > + f_out.file->f_pos = pos_out; > + } > + } > +out: > + fdput(f_in); > + fdput(f_out); > + return ret; > +} > diff --git a/include/linux/fs.h b/include/linux/fs.h > index cc008c3..c97aed8 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1631,6 +1631,7 @@ struct file_operations { > #ifndef CONFIG_MMU > unsigned (*mmap_capabilities)(struct file *); > #endif > + ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, int); > }; > > struct inode_operations { > @@ -1684,6 +1685,8 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *, > unsigned long, loff_t *); > extern ssize_t vfs_writev(struct file *, const struct iovec __user *, > unsigned long, loff_t *); > +extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *, > + loff_t, size_t, int); > > struct super_operations { > struct inode *(*alloc_inode)(struct super_block *sb); > diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h > index e016bd9..2b60f0c 100644 > --- a/include/uapi/asm-generic/unistd.h > +++ b/include/uapi/asm-generic/unistd.h > @@ -709,9 +709,11 @@ __SYSCALL(__NR_memfd_create, sys_memfd_create) > __SYSCALL(__NR_bpf, sys_bpf) > #define __NR_execveat 281 > __SC_COMP(__NR_execveat, sys_execveat, compat_sys_execveat) > +#define __NR_copy_file_range 282 > +__SYSCALL(__NR_copy_file_range, sys_copy_file_range) > > #undef __NR_syscalls > -#define __NR_syscalls 282 > +#define __NR_syscalls 283 > > /* > * All syscalls below here should go away really, > diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c > index 7995ef5..4e01cd9 100644 > --- a/kernel/sys_ni.c > +++ b/kernel/sys_ni.c > @@ -173,6 +173,7 @@ cond_syscall(sys_setfsuid); > cond_syscall(sys_setfsgid); > cond_syscall(sys_capget); > cond_syscall(sys_capset); > +cond_syscall(sys_copy_file_range); > > /* arch-specific weak syscall entries */ > cond_syscall(sys_pciconfig_read); > -- > 2.5.1 > > -- > 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
diff --git a/fs/read_write.c b/fs/read_write.c index 819ef3f..82c4933 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -16,6 +16,7 @@ #include <linux/pagemap.h> #include <linux/splice.h> #include <linux/compat.h> +#include <linux/mount.h> #include "internal.h" #include <asm/uaccess.h> @@ -1327,3 +1328,131 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, return do_sendfile(out_fd, in_fd, NULL, count, 0); } #endif + +/* + * copy_file_range() differs from regular file read and write in that it + * specifically allows return partial success. When it does so is up to + * the copy_file_range method. + */ +ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, + struct file *file_out, loff_t pos_out, + size_t len, int flags) +{ + struct inode *inode_in; + struct inode *inode_out; + ssize_t ret; + + if (flags) + return -EINVAL; + + if (len == 0) + return 0; + + /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */ + ret = rw_verify_area(READ, file_in, &pos_in, len); + if (ret >= 0) + ret = rw_verify_area(WRITE, file_out, &pos_out, len); + if (ret < 0) + return ret; + + if (!(file_in->f_mode & FMODE_READ) || + !(file_out->f_mode & FMODE_WRITE) || + (file_out->f_flags & O_APPEND) || + !file_in->f_op || !file_in->f_op->copy_file_range) + return -EBADF; + + inode_in = file_inode(file_in); + inode_out = file_inode(file_out); + + /* make sure offsets don't wrap and the input is inside i_size */ + if (pos_in + len < pos_in || pos_out + len < pos_out || + pos_in + len > i_size_read(inode_in)) + return -EINVAL; + + /* this could be relaxed once a method supports cross-fs copies */ + if (inode_in->i_sb != inode_out->i_sb || + file_in->f_path.mnt != file_out->f_path.mnt) + return -EXDEV; + + /* forbid ranges in the same file */ + if (inode_in == inode_out) + return -EINVAL; + + ret = mnt_want_write_file(file_out); + if (ret) + return ret; + + ret = file_in->f_op->copy_file_range(file_in, pos_in, file_out, pos_out, + len, flags); + if (ret > 0) { + fsnotify_access(file_in); + add_rchar(current, ret); + fsnotify_modify(file_out); + add_wchar(current, ret); + } + inc_syscr(current); + inc_syscw(current); + + mnt_drop_write_file(file_out); + + return ret; +} +EXPORT_SYMBOL(vfs_copy_file_range); + +SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in, + int, fd_out, loff_t __user *, off_out, + size_t, len, unsigned int, flags) +{ + loff_t pos_in; + loff_t pos_out; + struct fd f_in; + struct fd f_out; + ssize_t ret; + + f_in = fdget(fd_in); + f_out = fdget(fd_out); + if (!f_in.file || !f_out.file) { + ret = -EBADF; + goto out; + } + + ret = -EFAULT; + if (off_in) { + if (copy_from_user(&pos_in, off_in, sizeof(loff_t))) + goto out; + } else { + pos_in = f_in.file->f_pos; + } + + if (off_out) { + if (copy_from_user(&pos_out, off_out, sizeof(loff_t))) + goto out; + } else { + pos_out = f_out.file->f_pos; + } + + ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len, + flags); + if (ret > 0) { + pos_in += ret; + pos_out += ret; + + if (off_in) { + if (copy_to_user(off_in, &pos_in, sizeof(loff_t))) + ret = -EFAULT; + } else { + f_in.file->f_pos = pos_in; + } + + if (off_out) { + if (copy_to_user(off_out, &pos_out, sizeof(loff_t))) + ret = -EFAULT; + } else { + f_out.file->f_pos = pos_out; + } + } +out: + fdput(f_in); + fdput(f_out); + return ret; +} diff --git a/include/linux/fs.h b/include/linux/fs.h index cc008c3..c97aed8 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1631,6 +1631,7 @@ struct file_operations { #ifndef CONFIG_MMU unsigned (*mmap_capabilities)(struct file *); #endif + ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, int); }; struct inode_operations { @@ -1684,6 +1685,8 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *, unsigned long, loff_t *); extern ssize_t vfs_writev(struct file *, const struct iovec __user *, unsigned long, loff_t *); +extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *, + loff_t, size_t, int); struct super_operations { struct inode *(*alloc_inode)(struct super_block *sb); diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index e016bd9..2b60f0c 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -709,9 +709,11 @@ __SYSCALL(__NR_memfd_create, sys_memfd_create) __SYSCALL(__NR_bpf, sys_bpf) #define __NR_execveat 281 __SC_COMP(__NR_execveat, sys_execveat, compat_sys_execveat) +#define __NR_copy_file_range 282 +__SYSCALL(__NR_copy_file_range, sys_copy_file_range) #undef __NR_syscalls -#define __NR_syscalls 282 +#define __NR_syscalls 283 /* * All syscalls below here should go away really, diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 7995ef5..4e01cd9 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -173,6 +173,7 @@ cond_syscall(sys_setfsuid); cond_syscall(sys_setfsgid); cond_syscall(sys_capget); cond_syscall(sys_capset); +cond_syscall(sys_copy_file_range); /* arch-specific weak syscall entries */ cond_syscall(sys_pciconfig_read);