[Cluster-devel] [GFS2 PATCH] GFS2: Wake up io waiters whenever a flush is done
Bob Peterson
rpeterso at redhat.com
Sat Jan 7 03:19:25 UTC 2017
Hi,
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 at redhat.com>
---
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 4df349c..5028a9d 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -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;
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