jbd: fix error handling for checkpoint io

When a checkpointing IO fails, current JBD code doesn't check the error
and continue journaling.  This means latest metadata can be lost from both
the journal and filesystem.

This patch leaves the failed metadata blocks in the journal space and
aborts journaling in the case of log_do_checkpoint().  To achieve this, we
need to do:

1. don't remove the failed buffer from the checkpoint list where in
   the case of __try_to_free_cp_buf() because it may be released or
   overwritten by a later transaction
2. log_do_checkpoint() is the last chance, remove the failed buffer
   from the checkpoint list and abort the journal
3. when checkpointing fails, don't update the journal super block to
   prevent the journaled contents from being cleaned.  For safety,
   don't update j_tail and j_tail_sequence either
4. when checkpointing fails, notify this error to the ext3 layer so
   that ext3 don't clear the needs_recovery flag, otherwise the
   journaled contents are ignored and cleaned in the recovery phase
5. if the recovery fails, keep the needs_recovery flag
6. prevent cleanup_journal_tail() from being called between
   __journal_drop_transaction() and journal_abort() (a race issue
   between journal_flush() and __log_wait_for_space()

Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.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/include/linux/jbd.h b/include/linux/jbd.h
index 35d4f6342fac..346e2b80be7d 100644
--- a/include/linux/jbd.h
+++ b/include/linux/jbd.h
@@ -911,7 +911,7 @@ extern int	   journal_set_features
                    (journal_t *, unsigned long, unsigned long, unsigned long);
 extern int         journal_create     (journal_t *);
 extern int         journal_load       (journal_t *journal);
-extern void        journal_destroy    (journal_t *);
+extern int         journal_destroy    (journal_t *);
 extern int         journal_recover    (journal_t *journal);
 extern int         journal_wipe       (journal_t *, int);
 extern int         journal_skip_recovery        (journal_t *);