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dm mpath: delay retry of bypassed pg

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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>
This commit is contained in:
Mike Christie
2012-06-03 00:29:45 +01:00
committed by Alasdair G Kergon
parent 1fbdd2b3a3
commit f220fd4efb
1 changed files with 6 additions and 2 deletions
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8
drivers/md/dm-mpath.c
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@@ -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. * Loop through priority groups until we find a valid path.
* First time we skip PGs marked 'bypassed'. * 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 { do {
list_for_each_entry(pg, &m->priority_groups, list) { list_for_each_entry(pg, &m->priority_groups, list) {
if (pg->bypassed == bypassed) if (pg->bypassed == bypassed)
continue; 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; return;
}
} }
} while (bypassed--); } while (bypassed--);