dm rq: add DM_MAPIO_DELAY_REQUEUE to delay requeue of blk-mq requests
Otherwise blk-mq will immediately dispatch requests that are requeued
via a BLK_MQ_RQ_QUEUE_BUSY return from blk_mq_ops .queue_rq.
Delayed requeue is implemented using blk_mq_delay_kick_requeue_list()
with a delay of 5 secs. In the context of DM multipath (all paths down)
it doesn't make any sense to requeue more quickly.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 0d301d5..dbced7b 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -336,20 +336,21 @@
spin_unlock_irqrestore(q->queue_lock, flags);
}
-static void dm_mq_requeue_request(struct request *rq)
+static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)
{
struct request_queue *q = rq->q;
unsigned long flags;
blk_mq_requeue_request(rq);
+
spin_lock_irqsave(q->queue_lock, flags);
if (!blk_queue_stopped(q))
- blk_mq_kick_requeue_list(q);
+ blk_mq_delay_kick_requeue_list(q, msecs);
spin_unlock_irqrestore(q->queue_lock, flags);
}
static void dm_requeue_original_request(struct mapped_device *md,
- struct request *rq)
+ struct request *rq, bool delay_requeue)
{
int rw = rq_data_dir(rq);
@@ -359,7 +360,7 @@
if (!rq->q->mq_ops)
dm_old_requeue_request(rq);
else
- dm_mq_requeue_request(rq);
+ dm_mq_delay_requeue_request(rq, delay_requeue ? 5000 : 0);
rq_completed(md, rw, false);
}
@@ -389,7 +390,7 @@
return;
else if (r == DM_ENDIO_REQUEUE)
/* The target wants to requeue the I/O */
- dm_requeue_original_request(tio->md, tio->orig);
+ dm_requeue_original_request(tio->md, tio->orig, false);
else {
DMWARN("unimplemented target endio return value: %d", r);
BUG();
@@ -629,8 +630,8 @@
/*
* Returns:
- * 0 : the request has been processed
- * DM_MAPIO_REQUEUE : the original request needs to be requeued
+ * DM_MAPIO_* : the request has been processed as indicated
+ * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued
* < 0 : the request was completed due to failure
*/
static int map_request(struct dm_rq_target_io *tio, struct request *rq,
@@ -643,6 +644,8 @@
if (tio->clone) {
clone = tio->clone;
r = ti->type->map_rq(ti, clone, &tio->info);
+ if (r == DM_MAPIO_DELAY_REQUEUE)
+ return DM_MAPIO_REQUEUE; /* .request_fn requeue is always immediate */
} else {
r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
if (r < 0) {
@@ -650,9 +653,8 @@
dm_kill_unmapped_request(rq, r);
return r;
}
- if (r != DM_MAPIO_REMAPPED)
- return r;
- if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
+ if (r == DM_MAPIO_REMAPPED &&
+ setup_clone(clone, rq, tio, GFP_ATOMIC)) {
/* -ENOMEM */
ti->type->release_clone_rq(clone);
return DM_MAPIO_REQUEUE;
@@ -671,7 +673,10 @@
break;
case DM_MAPIO_REQUEUE:
/* The target wants to requeue the I/O */
- dm_requeue_original_request(md, tio->orig);
+ break;
+ case DM_MAPIO_DELAY_REQUEUE:
+ /* The target wants to requeue the I/O after a delay */
+ dm_requeue_original_request(md, tio->orig, true);
break;
default:
if (r > 0) {
@@ -681,10 +686,9 @@
/* The target wants to complete the I/O */
dm_kill_unmapped_request(rq, r);
- return r;
}
- return 0;
+ return r;
}
static void dm_start_request(struct mapped_device *md, struct request *orig)
@@ -727,7 +731,7 @@
struct mapped_device *md = tio->md;
if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE)
- dm_requeue_original_request(md, rq);
+ dm_requeue_original_request(md, rq, false);
}
ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)