From f220fd4efb334a772f9a14b2372175f38d89355e Mon Sep 17 00:00:00 2001
From: Mike Christie <michaelc@cs.wisc.edu>
Date: Sun, 3 Jun 2012 00:29:45 +0100
Subject: [PATCH] dm mpath: delay retry of bypassed pg
If I/O needs retrying and only bypassed priority groups are available,
set the pg_init_delay_retry flag to wait before retrying.
If, for example, the reason for the bypass is that the controller is
getting reset or there is a firmware upgrade happening, retrying right
away would cause a flood of log messages and retries for what could be a
few seconds or even several minutes.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
drivers/md/dm-mpath.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index c35160786cf4e..2469ba68dc2ba 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -329,14 +329,18 @@ static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
/*
* Loop through priority groups until we find a valid path.
* First time we skip PGs marked 'bypassed'.
- * Second time we only try the ones we skipped.
+ * Second time we only try the ones we skipped, but set
+ * pg_init_delay_retry so we do not hammer controllers.
*/
do {
list_for_each_entry(pg, &m->priority_groups, list) {
if (pg->bypassed == bypassed)
continue;
- if (!__choose_path_in_pg(m, pg, nr_bytes))
+ if (!__choose_path_in_pg(m, pg, nr_bytes)) {
+ if (!bypassed)
+ m->pg_init_delay_retry = 1;
return;
+ }
}
} while (bypassed--);
--
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