jbd2: correctly unescape journal data blocks

Fix a long-standing typo (predating git) that will cause data corruption if a
journal data block needs unescaping.  At the moment the wrong buffer head's
data is being unescaped.

To test this case mount a filesystem with data=journal, start creating and
deleting a bunch of files containing only JBD2_MAGIC_NUMBER (0xc03b3998), then
pull the plug on the device.  Without this patch the files will contain zeros
instead of the correct data after recovery.

Signed-off-by: Duane Griffin <duaneg@dghda.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 146411387ada..5d0405a9e7ca 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -535,7 +535,7 @@ static int do_one_pass(journal_t *journal,
                                         memcpy(nbh->b_data, obh->b_data,
                                                         journal->j_blocksize);
                                         if (flags & JBD2_FLAG_ESCAPE) {
-                                                *((__be32 *)bh->b_data) =
+                                                *((__be32 *)nbh->b_data) =
                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
                                         }