* [PATCH] ioctl: add note regarding CLONE_RANGE(len=0) behaviour
@ 2014-02-06 14:29 David Disseldorp
0 siblings, 0 replies; only message in thread
From: David Disseldorp @ 2014-02-06 14:29 UTC (permalink / raw)
To: linux-btrfs; +Cc: David Disseldorp
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>
---
ioctl.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/ioctl.h b/ioctl.h
index a589cd7..f7d435d 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -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;
--
1.8.4.5
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2014-02-06 14:29 [PATCH] ioctl: add note regarding CLONE_RANGE(len=0) behaviour David Disseldorp
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