Commit b63f5e84 authored Jan 06, 2017 by Bob Peterson

GFS2: Wake up io waiters whenever a flush is done

Before this patch, if a process called function gfs2_log_reserve to
reserve some journal blocks, but the journal not enough blocks were
free, it would call io_schedule. However, in the log flush daemon,
it woke up the waiters only if an gfs2_ail_flush was no longer
required. This resulted in situations where processes would wait
forever because the number of blocks required was so high that it
pushed the journal into a perpetual state of flush being required.

This patch changes the logd daemon so that it wakes up io waiters
every time the log is actually flushed.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>

parent f07b3520

fs/gfs2/log.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -918,12 +918,15 @@ int gfs2_logd(void *data)
		struct gfs2_sbd *sdp = data;
		unsigned long t = 1;
		DEFINE_WAIT(wait);
		bool did_flush;

		while (!kthread_should_stop()) {

		did_flush = false;
		if (gfs2_jrnl_flush_reqd(sdp) \|\| t == 0) {
		gfs2_ail1_empty(sdp);
		gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
		did_flush = true;
		}

		if (gfs2_ail_flush_reqd(sdp)) {
		@@ -931,9 +934,10 @@ int gfs2_logd(void *data)
		gfs2_ail1_wait(sdp);
		gfs2_ail1_empty(sdp);
		gfs2_log_flush(sdp, NULL, NORMAL_FLUSH);
		did_flush = true;
		}

		if (!gfs2_ail_flush_reqd(sdp))
		if (!gfs2_ail_flush_reqd(sdp) \|\| did_flush)
		wake_up(&sdp->sd_log_waitq);

		t = gfs2_tune_get(sdp, gt_logd_secs) * HZ;