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ioctl_fideduperange.2: Minor tweaks 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2016-06-08 12:31:06 +02:00
parent 990a64f7e3
commit 2db75216ad
1 changed files with 19 additions and 22 deletions
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41
man2/ioctl_fideduperange.2
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@ -28,7 +28,7 @@ ioctl_fideduperange \- share some the data of one file with another file
If a filesystem supports files sharing physical storage between multiple
files, this
.BR ioctl (2)
system call can be used to make some of the data in the
operation can be used to make some of the data in the
.B src_fd
file appear in the
.B dest_fd
@ -52,12 +52,12 @@ This information is conveyed in a structure of the following form:
.nf
struct file_dedupe_range {
__u64 src_offset;
__u64 src_length;
__u16 dest_count;
__u16 reserved1;
__u32 reserved2;
struct file_dedupe_range_info info[0];
__u64 src_offset;
__u64 src_length;
__u16 dest_count;
__u16 reserved1;
__u32 reserved2;
struct file_dedupe_range_info info[0];
};
.fi
.in
@ -129,11 +129,11 @@ regions in directories.
.TP
.B EINVAL
The filesystem does not support deduplicating the ranges of the given files.
This error can also appear if either file descriptor represents a device, fifo,
or socket.
This error can also appear if either file descriptor represents
a device, FIFO, or socket.
Disk filesystems generally require the offset and length arguments
to be aligned to the fundamental block size.
Neither btrfs nor XFS support
Neither Btrfs nor XFS support
overlapping deduplication ranges in the same file.
.TP
.B EBADF
@ -156,21 +156,18 @@ Swap files cannot share storage.
.B EOPNOTSUPP
This can appear if the filesystem does not support deduplicating 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.
Some filesystems may limit the amount of data that can be deduplicated in a
single call.
.SH CONFORMING TO
This API is Linux-specific.
This ioctl was previously known as
.B BTRFS_IOC_FILE_EXTENT_SAME
and was private to btrfs.
.fi
.in
and was private to Btrfs.
.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.
Some filesystems may limit the amount of data that can be deduplicated in a
single call.
.SH SEE ALSO
.BR ioctl (2)