[patch 70/76] jbd2: correctly unescape journal data blocks

[Chris Wright]

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

From: Duane Griffin <duaneg@xxxxxxxxx>

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@xxxxxxxxx>
Acked-by: Jan Kara <jack@xxxxxxx>
Cc: <linux-ext4@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 fs/jbd2/recovery.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -488,7 +488,7 @@ static int do_one_pass(journal_t *journa
 					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);
 					}
 

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