reiserfs, kill-the-BKL: fix unsafe j_flush_mutex lock
Impact: fix a deadlock
The j_flush_mutex is acquired safely in journal.c:
if we can't take it, we free the reiserfs per superblock lock
and wait a bit.
But we have a remaining place in kupdate_transactions() where
j_flush_mutex is still acquired traditionnaly. Thus the following
scenario (warned by lockdep) can happen:
A B
mutex_lock(&write_lock) mutex_lock(&write_lock)
mutex_lock(&j_flush_mutex) mutex_lock(&j_flush_mutex) //block
mutex_unlock(&write_lock)
sleep...
mutex_lock(&write_lock) //deadlock
Fix this by using reiserfs_mutex_lock_safe() in kupdate_transactions().
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Alessio Igor Bogani <abogani@texware.it>
Cc: Jeff Mahoney <jeffm@suse.com>
LKML-Reference: <1239660635-12940-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 438c71f..0ba98ca 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -1826,7 +1826,7 @@
struct reiserfs_journal *journal = SB_JOURNAL(s);
chunk.nr = 0;
- mutex_lock(&journal->j_flush_mutex);
+ reiserfs_mutex_lock_safe(&journal->j_flush_mutex, s);
if (!journal_list_still_alive(s, orig_trans_id)) {
goto done;
}