Btrfs: Fix file clone when source offset is not 0
Suppose:
- the source extent is: [0, 100]
- the src offset is 10
- the clone length is 90
- the dest offset is 0
This statement:
new_key.offset = key.offset + destoff - off
will produce such an extent for the dest file:
[ino, BTRFS_EXTENT_DATA_KEY, -10]
, which is obviously wrong.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f87552a..1b61dab 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1788,7 +1788,10 @@
memcpy(&new_key, &key, sizeof(new_key));
new_key.objectid = inode->i_ino;
- new_key.offset = key.offset + destoff - off;
+ if (off <= key.offset)
+ new_key.offset = key.offset + destoff - off;
+ else
+ new_key.offset = destoff;
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {