Merge tag 'block-5.15-2021-09-11' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:

 - NVMe pull request from Christoph:
     - fix nvmet command set reporting for passthrough controllers (Adam Manzanares)
     - update a MAINTAINERS email address (Chaitanya Kulkarni)
     - set QUEUE_FLAG_NOWAIT for nvme-multipth (me)
     - handle errors from add_disk() (Luis Chamberlain)
     - update the keep alive interval when kato is modified (Tatsuya Sasaki)
     - fix a buffer overrun in nvmet_subsys_attr_serial (Hannes Reinecke)
     - do not reset transport on data digest errors in nvme-tcp (Daniel Wagner)
     - only call synchronize_srcu when clearing current path (Daniel Wagner)
     - revalidate paths during rescan (Hannes Reinecke)

 - Split out the fs/block_dev into block/fops.c and block/bdev.c, which
   has been long overdue. Do this now before -rc1, to avoid annoying
   conflicts due to this (Christoph)

 - blk-throtl use-after-free fix (Li)

 - Improve plug depth for multi-device plugs, greatly increasing md
   resync performance (Song)

 - blkdev_show() locking fix (Tetsuo)

 - n64cart error check fix (Yang)

* tag 'block-5.15-2021-09-11' of git://git.kernel.dk/linux-block:
  n64cart: fix return value check in n64cart_probe()
  blk-mq: allow 4x BLK_MAX_REQUEST_COUNT at blk_plug for multiple_queues
  block: move fs/block_dev.c to block/bdev.c
  block: split out operations on block special files
  blk-throttle: fix UAF by deleteing timer in blk_throtl_exit()
  block: genhd: don't call blkdev_show() with major_names_lock held
  nvme: update MAINTAINERS email address
  nvme: add error handling support for add_disk()
  nvme: only call synchronize_srcu when clearing current path
  nvme: update keep alive interval when kato is modified
  nvme-tcp: Do not reset transport on data digest errors
  nvmet: fixup buffer overrun in nvmet_subsys_attr_serial()
  nvmet: return bool from nvmet_passthru_ctrl and nvmet_is_passthru_req
  nvmet: looks at the passthrough controller when initializing CAP
  nvme: move nvme_multi_css into nvme.h
  nvme-multipath: revalidate paths during rescan
  nvme-multipath: set QUEUE_FLAG_NOWAIT

1 files changed, 13 insertions, 1 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 65d3a63aecc6..108a352051be 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2135,6 +2135,18 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
 	}
 }
 
+/*
+ * Allow 4x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
+ * queues. This is important for md arrays to benefit from merging
+ * requests.
+ */
+static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
+{
+	if (plug->multiple_queues)
+		return BLK_MAX_REQUEST_COUNT * 4;
+	return BLK_MAX_REQUEST_COUNT;
+}
+
 /**
  * blk_mq_submit_bio - Create and send a request to block device.
  * @bio: Bio pointer.
@@ -2231,7 +2243,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
 		else
 			last = list_entry_rq(plug->mq_list.prev);
 
-		if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
+		if (request_count >= blk_plug_max_rq_count(plug) || (last &&
 		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
 			blk_flush_plug_list(plug, false);
 			trace_block_plug(q);