From: Duane Griffin <duaneg@dghda.com>
Date: Thu, 20 Mar 2008 00:00:53 +0000 (-0700)
Subject: jbd: correctly unescape journal data blocks
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=439aeec639d7c57f3561054a6d315c40fd24bb74;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

jbd: 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 JFS_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>
---

diff --git a/fs/jbd/recovery.c b/fs/jbd/recovery.c
index 2b8edf4d6eaa..43bc5e5ed064 100644
--- a/fs/jbd/recovery.c
+++ b/fs/jbd/recovery.c
@@ -478,7 +478,7 @@ static int do_one_pass(journal_t *journal,
 					memcpy(nbh->b_data, obh->b_data,
 							journal->j_blocksize);
 					if (flags & JFS_FLAG_ESCAPE) {
-						*((__be32 *)bh->b_data) =
+						*((__be32 *)nbh->b_data) =
 						cpu_to_be32(JFS_MAGIC_NUMBER);
 					}