Patch "md: update the optimal I/O size on reshape" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    md: update the optimal I/O size on reshape

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     md-update-the-optimal-i-o-size-on-reshape.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3a93f2758554317c08e90b520cd24ebffbe0ba82
Author: Christoph Hellwig <hch@xxxxxx>
Date:   Thu Sep 24 08:51:33 2020 +0200

    md: update the optimal I/O size on reshape
    
    [ Upstream commit 16ef510139315a2147ee7525796f8dbd4e4b7864 ]
    
    The raid5 and raid10 drivers currently update the read-ahead size,
    but not the optimal I/O size on reshape.  To prepare for deriving the
    read-ahead size from the optimal I/O size make sure it is updated
    as well.
    
    Signed-off-by: Christoph Hellwig <hch@xxxxxx>
    Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
    Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
    Acked-by: Song Liu <song@xxxxxxxxxx>
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Stable-dep-of: f0ddb83da3cb ("md/raid10: fix memleak of md thread")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 68447e1525057..b37e3cd4e3673 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3735,10 +3735,20 @@ static struct r10conf *setup_conf(struct mddev *mddev)
 	return ERR_PTR(err);
 }
 
+static void raid10_set_io_opt(struct r10conf *conf)
+{
+	int raid_disks = conf->geo.raid_disks;
+
+	if (!(conf->geo.raid_disks % conf->geo.near_copies))
+		raid_disks /= conf->geo.near_copies;
+	blk_queue_io_opt(conf->mddev->queue, (conf->mddev->chunk_sectors << 9) *
+			 raid_disks);
+}
+
 static int raid10_run(struct mddev *mddev)
 {
 	struct r10conf *conf;
-	int i, disk_idx, chunk_size;
+	int i, disk_idx;
 	struct raid10_info *disk;
 	struct md_rdev *rdev;
 	sector_t size;
@@ -3774,18 +3784,13 @@ static int raid10_run(struct mddev *mddev)
 	mddev->thread = conf->thread;
 	conf->thread = NULL;
 
-	chunk_size = mddev->chunk_sectors << 9;
 	if (mddev->queue) {
 		blk_queue_max_discard_sectors(mddev->queue,
 					      mddev->chunk_sectors);
 		blk_queue_max_write_same_sectors(mddev->queue, 0);
 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
-		blk_queue_io_min(mddev->queue, chunk_size);
-		if (conf->geo.raid_disks % conf->geo.near_copies)
-			blk_queue_io_opt(mddev->queue, chunk_size * conf->geo.raid_disks);
-		else
-			blk_queue_io_opt(mddev->queue, chunk_size *
-					 (conf->geo.raid_disks / conf->geo.near_copies));
+		blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
+		raid10_set_io_opt(conf);
 	}
 
 	rdev_for_each(rdev, mddev) {
@@ -4748,6 +4753,7 @@ static void end_reshape(struct r10conf *conf)
 		stripe /= conf->geo.near_copies;
 		if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
 			conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
+		raid10_set_io_opt(conf);
 	}
 	conf->fullsync = 0;
 }
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d0c3f49c8c162..113ba084fab45 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7159,6 +7159,12 @@ static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded
 	return 0;
 }
 
+static void raid5_set_io_opt(struct r5conf *conf)
+{
+	blk_queue_io_opt(conf->mddev->queue, (conf->chunk_sectors << 9) *
+			 (conf->raid_disks - conf->max_degraded));
+}
+
 static int raid5_run(struct mddev *mddev)
 {
 	struct r5conf *conf;
@@ -7448,8 +7454,7 @@ static int raid5_run(struct mddev *mddev)
 
 		chunk_size = mddev->chunk_sectors << 9;
 		blk_queue_io_min(mddev->queue, chunk_size);
-		blk_queue_io_opt(mddev->queue, chunk_size *
-				 (conf->raid_disks - conf->max_degraded));
+		raid5_set_io_opt(conf);
 		mddev->queue->limits.raid_partial_stripes_expensive = 1;
 		/*
 		 * We can only discard a whole stripe. It doesn't make sense to
@@ -8043,6 +8048,7 @@ static void end_reshape(struct r5conf *conf)
 						   / PAGE_SIZE);
 			if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
 				conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
+			raid5_set_io_opt(conf);
 		}
 	}
 }