Merge tag 'block-5.15-2021-09-05' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Was going to send this one in later this week, but given that -Werror
  is now enabled (or at least available), the mq-deadline fix really
  should go in for the folks hitting that.

   - Ensure dd_queued() is only there if needed (Geert)

   - Fix a kerneldoc warning for bio_alloc_kiocb()

   - BFQ fix for queue merging

   - loop locking fix (Tetsuo)"

* tag 'block-5.15-2021-09-05' of git://git.kernel.dk/linux-block:
  loop: reduce the loop_ctl_mutex scope
  bio: fix kerneldoc documentation for bio_alloc_kiocb()
  block, bfq: honor already-setup queue merges
  block/mq-deadline: Move dd_queued() to fix defined but not used warning

3 files changed, 20 insertions, 10 deletions

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 480e1a134859..dd13c2bbc29c 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2662,6 +2662,15 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
 	 * are likely to increase the throughput.
 	 */
 	bfqq->new_bfqq = new_bfqq;
+	/*
+	 * The above assignment schedules the following redirections:
+	 * each time some I/O for bfqq arrives, the process that
+	 * generated that I/O is disassociated from bfqq and
+	 * associated with new_bfqq. Here we increases new_bfqq->ref
+	 * in advance, adding the number of processes that are
+	 * expected to be associated with new_bfqq as they happen to
+	 * issue I/O.
+	 */
 	new_bfqq->ref += process_refs;
 	return new_bfqq;
 }
@@ -2724,6 +2733,10 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 {
 	struct bfq_queue *in_service_bfqq, *new_bfqq;
 
+	/* if a merge has already been setup, then proceed with that first */
+	if (bfqq->new_bfqq)
+		return bfqq->new_bfqq;
+
 	/*
 	 * Check delayed stable merge for rotational or non-queueing
 	 * devs. For this branch to be executed, bfqq must not be
@@ -2825,9 +2838,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 	if (bfq_too_late_for_merging(bfqq))
 		return NULL;
 
-	if (bfqq->new_bfqq)
-		return bfqq->new_bfqq;
-
 	if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
 		return NULL;
 
diff --git a/block/bio.c b/block/bio.c
index e16849f46b0e..5df3dd282e40 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1688,7 +1688,7 @@ EXPORT_SYMBOL(bioset_init_from_src);
 /**
  * bio_alloc_kiocb - Allocate a bio from bio_set based on kiocb
  * @kiocb:	kiocb describing the IO
- * @nr_iovecs:	number of iovecs to pre-allocate
+ * @nr_vecs:	number of iovecs to pre-allocate
  * @bs:		bio_set to allocate from
  *
  * Description:
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 3c3693c34f06..7f3c3932b723 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -270,12 +270,6 @@ deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
 	deadline_remove_request(rq->q, per_prio, rq);
 }
 
-/* Number of requests queued for a given priority level. */
-static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
-{
-	return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio);
-}
-
 /*
  * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
@@ -953,6 +947,12 @@ static int dd_async_depth_show(void *data, struct seq_file *m)
 	return 0;
 }
 
+/* Number of requests queued for a given priority level. */
+static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
+{
+	return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio);
+}
+
 static int dd_queued_show(void *data, struct seq_file *m)
 {
 	struct request_queue *q = data;