# touch /mnt/dst
# clone_range -s 8192 -l 4096 /mnt/src /mnt/dst
# ls -l /mnt/dst
-rw-r--r-- 1 root root 4096 dst
# umount /mnt
# btrfs-debug-tree /dev/sda7
...
item 11 key (258 EXTENT_DATA 0) itemoff 3230 itemsize 53
extent data disk byte 12582912 nr 49152
extent data offset 8192 nr 12288 ram 49152
extent compression 0
num_bytes should be 4096 not 12288.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
---
fs/btrfs/ioctl.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 660a6c8..3351b1b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2331,14 +2331,21 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
if (type == BTRFS_FILE_EXTENT_REG ||
type == BTRFS_FILE_EXTENT_PREALLOC) {
+ /*
+ * a | --- range to clone ---| b
+ * | ------------- extent ------------- |
+ */
+
+ /* substract range b */
+ if (key.offset + datal > off + len)
+ datal = off + len - key.offset;
+
+ /* substract range a */
if (off > key.offset) {
datao += off - key.offset;
datal -= off - key.offset;
}
- if (key.offset + datal > off + len)
- datal = off + len - key.offset;
-
ret = btrfs_drop_extents(trans, inode,
new_key.offset,
new_key.offset + datal,
--
1.7.3.1
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