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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-06-08 12:17:02 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-06-08 12:34:54 +0200 |
| commit | 603fc95a2b0d3a4a860132d38ab6d9e26db73ced (patch) | |
| tree | e9f80df16eb12908e0266306f9ecdc1ea7b108ba | |
| parent | 1d691addc217ec5757561b8f8aa7462e29bbe0c5 (diff) | |
| download | man-pages-603fc95a2b0d3a4a860132d38ab6d9e26db73ced.tar.gz | |
ioctl_ficlonerange.2: Minor tweaks
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
| -rw-r--r-- | man2/ioctl_ficlonerange.2 | 38 |
1 files changed, 20 insertions, 18 deletions
diff --git a/man2/ioctl_ficlonerange.2 b/man2/ioctl_ficlonerange.2 index eee2a3f4c0..376f685c2a 100644 --- a/man2/ioctl_ficlonerange.2 +++ b/man2/ioctl_ficlonerange.2 @@ -30,10 +30,10 @@ ioctl_ficlonerange, ioctl_ficlone \- share some the data of one file with anothe If a filesystem supports files sharing physical storage between multiple files ("reflink"), this .BR ioctl (2) -system call can be used to make some of the data in the -.B src_fd +operation can be used to make some of the data in the +.I src_fd file appear in the -.B dest_fd +.I dest_fd file by sharing the underlying storage, which is faster than making a separate physical copy of the data. If a file write should occur to a shared region, @@ -58,10 +58,10 @@ the following form: .nf struct file_clone_range { - __s64 src_fd; - __u64 src_offset; - __u64 src_length; - __u64 dest_offset; + __s64 src_fd; + __u64 src_offset; + __u64 src_length; + __u64 dest_offset; }; .fi @@ -69,7 +69,9 @@ struct file_clone_range { Clones are atomic with regards to concurrent writes, so no locks need to be taken to obtain a consistent cloned copy. -The FICLONE ioctl clones entire files. +The +.B FICLONE +ioctl clones entire files. .SH RETURN VALUE On error, \-1 is returned, and .I errno @@ -89,18 +91,18 @@ regions in directories. .B EINVAL The filesystem does not support reflinking the ranges of the given files. This error can also appear if either file descriptor represents -a device, fifo, or socket. +a device, FIFO, or socket. Disk filesystems generally require the offset and length arguments to be aligned to the fundamental block size. -XFS and btrfs do not support +XFS and Btrfs do not support overlapping reflink ranges in the same file. .TP .B EBADF .IR src_fd is not open for reading; .IR dest_fd -is not open for writing or is open for append-only writes; or the filesystem -which +is not open for writing or is open for append-only writes; +or the filesystem which .IR src_fd resides on does not support reflink. .TP @@ -115,17 +117,17 @@ Swap files cannot share storage. .B EOPNOTSUPP This can appear if the filesystem does not support reflinking either file descriptor. -.SH NOTES -Because a copy on write operation requires the allocation of new storage, the -.B fallocate (2) -operation may un-share shared blocks to guarantee that subsequent writes will -not fail because of lack of disk space. .SH CONFORMING TO This API is Linux-specific. This ioctl was previously known as .B BTRFS_IOC_CLONE_RANGE -and was private to btrfs. +and was private to Btrfs. .fi .in +.SH NOTES +Because a copy-on-write operation requires the allocation of new storage, the +.BR fallocate (2) +operation may unshare shared blocks to guarantee that subsequent writes will +not fail because of lack of disk space. .SH SEE ALSO .BR ioctl (2) |