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fs: jbd2: pull your plug when waiting for space 

Two cps in parallel managed to stall the the ext4 fs. It seems that
journal code is either waiting for locks or sleeping waiting for
something to happen. This seems similar to what Mike observed on ext3,
here is his description:

|With an -rt kernel, and a heavy sync IO load, tasks can jam
|up on journal locks without unplugging, which can lead to
|terminal IO starvation.  Unplug and schedule when waiting
|for space.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
This commit is contained in:
Sebastian Andrzej Siewior 2014-02-17 17:30:03 +01:00 committed by Alibek Omarov
parent c80a59e1aa
commit f9b2a5eee5
1 changed files with 2 additions and 0 deletions
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2
fs/jbd2/checkpoint.c
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@ -125,6 +125,8 @@ void __jbd2_log_wait_for_space(journal_t *journal)
if (journal->j_flags & JBD2_ABORT)
return;
write_unlock(&journal->j_state_lock);
if (current->plug)
io_schedule();
mutex_lock(&journal->j_checkpoint_mutex);
/*