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.vanass...@sandisk.com>
Reviewed-by: Hannes Reinecke <h...@suse.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: <sta...@vger.kernel.org>
---
drivers/md/dm-mpath.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index cc41e34607c3..d739688246a0 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -322,13 +322,16 @@ static int __pg_init_all_paths(struct multipath *m)
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)
{
unsigned long flags;
+ int ret;
spin_lock_irqsave(&m->lock, flags);
- __pg_init_all_paths(m);
+ ret = __pg_init_all_paths(m);
spin_unlock_irqrestore(&m->lock, flags);
+
+ return ret;
}
static void __switch_pg(struct multipath *m, struct priority_group *pg)
@@ -485,7 +488,6 @@ static int multipath_clone_and_map(struct dm_target *ti,
struct request *rq,
struct request **__clone)
{
struct multipath *m = ti->private;
- int r = DM_MAPIO_REQUEUE;
size_t nr_bytes = blk_rq_bytes(rq);
struct pgpath *pgpath;
struct block_device *bdev;
@@ -504,8 +506,8 @@ static int multipath_clone_and_map(struct dm_target *ti,
struct request *rq,
return -EIO; /* Failed */
} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
- pg_init_all_paths(m);
- return r;
+ return pg_init_all_paths(m) == 0 ? DM_MAPIO_REQUEUE :
+ DM_MAPIO_DELAY_REQUEUE;
}
memset(mpio, 0, sizeof(*mpio));
--
2.12.2
--
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