[PATCH 3.14 65/88] Btrfs: fix crash on endio of reading corrupted block

[Greg Kroah-Hartman]

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Liu Bo <bo.li.liu@xxxxxxxxxx>

commit 38c1c2e44bacb37efd68b90b3f70386a8ee370ee upstream.

The crash is

------------[ cut here ]------------
kernel BUG at fs/btrfs/extent_io.c:2124!
[...]
Workqueue: btrfs-endio normal_work_helper [btrfs]
RIP: 0010:[<ffffffffa02d6055>]  [<ffffffffa02d6055>] end_bio_extent_readpage+0xb45/0xcd0 [btrfs]

This is in fact a regression.

It is because we forgot to increase @offset properly in reading corrupted block,
so that the @offset remains, and this leads to checksum errors while reading
left blocks queued up in the same bio, and then ends up with hiting the above
BUG_ON.

Reported-by: Chris Murphy <lists@xxxxxxxxxxxxxxxxx>
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Signed-off-by: Chris Mason <clm@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/btrfs/extent_io.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2525,6 +2525,7 @@ static void end_bio_extent_readpage(stru
 					test_bit(BIO_UPTODATE, &bio->bi_flags);
 				if (err)
 					uptodate = 0;
+				offset += len;
 				continue;
 			}
 		}


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