linux-ext4 - [PATCH] jbd2: correctly unescape journal data blocks

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Message-Id: <1205606985-22645-3-git-send-email-duaneg@dghda.com>
Date:	Sat, 15 Mar 2008 18:49:45 +0000
From:	"Duane Griffin" <duaneg@...da.com>
To:	sct@...hat.com, akpm@...ux-foundation.org
Cc:	linux-ext4@...r.kernel.org, duaneg@...da.com
Subject: [PATCH] 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@...da.com>
---
 fs/jbd2/recovery.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 1464113..5d0405a 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);
 					}
 
-- 
1.5.3.7

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