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dm mpath: delay requeuing while path initialization is in progress 

Requeuing a request immediately while path initialization is ongoing
causes high CPU usage, something that is undesired.  Hence delay
requeuing while path initialization is in progress.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Bart Van Assche 2017-04-27 10:11:16 -07:00 committed by Mike Snitzer
parent 7083abbbfc
commit c1d7ecf7ca
1 changed files with 7 additions and 3 deletions
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10
drivers/md/dm-mpath.c
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@ -322,13 +322,16 @@ static int __pg_init_all_paths(struct multipath *m)
return atomic_read(&m->pg_init_in_progress); return atomic_read(&m->pg_init_in_progress);
} }
static void pg_init_all_paths(struct multipath *m) static int pg_init_all_paths(struct multipath *m)
{ {
int ret;
unsigned long flags; unsigned long flags;
spin_lock_irqsave(&m->lock, flags); spin_lock_irqsave(&m->lock, flags);
__pg_init_all_paths(m); ret = __pg_init_all_paths(m);
spin_unlock_irqrestore(&m->lock, flags); spin_unlock_irqrestore(&m->lock, flags);
return ret;
} }
static void __switch_pg(struct multipath *m, struct priority_group *pg) static void __switch_pg(struct multipath *m, struct priority_group *pg)
@ -503,7 +506,8 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
return -EIO; /* Failed */ return -EIO; /* Failed */
} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) || } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) { test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
pg_init_all_paths(m); if (pg_init_all_paths(m))
return DM_MAPIO_DELAY_REQUEUE;
return DM_MAPIO_REQUEUE; return DM_MAPIO_REQUEUE;
} }