From: Frederic Weisbecker Date: Mon, 13 Apr 2009 22:10:35 +0000 (+0200) Subject: reiserfs, kill-the-BKL: fix unsafe j_flush_mutex lock X-Git-Tag: firefly_0821_release~9833^2~3455^2~50 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a412f9efdd6424bf4bf28c8e8c92060b5e975482;p=firefly-linux-kernel-4.4.55.git 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 Cc: Alessio Igor Bogani Cc: Jeff Mahoney LKML-Reference: <1239660635-12940-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c index 438c71f0bc91..0ba98ca367c7 100644 --- a/fs/reiserfs/journal.c +++ b/fs/reiserfs/journal.c @@ -1826,7 +1826,7 @@ static int kupdate_transactions(struct super_block *s, 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; }