ioctl: add note regarding CLONE_RANGE(len=0) behaviour

A BTRFS_IOC_CLONE_RANGE request with a src_length value of zero has the
effect of cloning all data from src_offset through to end-of-file.

Document this behaviour in the header file for those who (like me)
incorrectly assume that no data is cloned in such a case.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
master
David Disseldorp 2014-02-06 15:29:18 +01:00 committed by Chris Mason
parent afb47079fa
commit 1484081f61
1 changed files with 1 additions and 0 deletions

View File

@ -506,6 +506,7 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
#define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \
struct btrfs_ioctl_vol_args)
/* With a @src_length of zero, the range from @src_offset->EOF is cloned! */
struct btrfs_ioctl_clone_range_args {
__s64 src_fd;
__u64 src_offset, src_length;