[PATCH 1/2] btrfs: pass unaligned length to btrfs_cmp_data()

[Mark Fasheh <mfasheh@suse.de>]

In the case that we dedupe the tail of a file, we might expand the dedupe
len out to the end of our last block. We don't want to compare data past
i_size however, so pass the original length to btrfs_cmp_data().

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
---
 fs/btrfs/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 2d24ff4..2deea1f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2933,7 +2933,8 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
 		goto out_unlock;
 	}
 
-	ret = btrfs_cmp_data(src, loff, dst, dst_loff, len);
+	/* pass original length for comparison so we stay within i_size */
+	ret = btrfs_cmp_data(src, loff, dst, dst_loff, olen);
 	if (ret == 0)
 		ret = btrfs_clone(src, dst, loff, olen, len, dst_loff);
 
-- 
2.1.2