jbd: correctly unescape journal data blocks

From: "Duane Griffin" <[email protected]>

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.

---

 fs/jbd/recovery.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN fs/jbd/recovery.c~jbd-correctly-unescape-journal-data-blocks fs/jbd/recovery.c
@@ -478,7 +478,7 @@ static int do_one_pass(journal_t *journa
 					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);
 					}
 

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