FAILED: patch "[PATCH] block: fix revalidate performance regression" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 47fe1c3064c6bc1bfa3c032ff78e603e5dd6e5bc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023060549-smolder-human-a813@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 47fe1c3064c6bc1bfa3c032ff78e603e5dd6e5bc Mon Sep 17 00:00:00 2001
From: Damien Le Moal <dlemoal@kernel.org>
Date: Mon, 29 May 2023 16:32:37 +0900
Subject: [PATCH] block: fix revalidate performance regression

The scsi driver function sd_read_block_characteristics() always calls
disk_set_zoned() to a disk zoned model correctly, in case the device
model changed. This is done even for regular disks to set the zoned
model to BLK_ZONED_NONE and free any zone related resources if the drive
previously was zoned.

This behavior significantly impact the time it takes to revalidate disks
on a large system as the call to disk_clear_zone_settings() done from
disk_set_zoned() for the BLK_ZONED_NONE case results in the device
request queued to be frozen, even if there are no zone resources to
free.

Avoid this overhead for non-zoned devices by not calling
disk_clear_zone_settings() in disk_set_zoned() if the device model
was already set to BLK_ZONED_NONE, which is always the case for regular
devices.

Reported by: Brian Bunker <brian@purestorage.com>

Fixes: 508aebb80527 ("block: introduce blk_queue_clear_zone_settings()")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230529073237.1339862-1-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 896b4654ab00..4dd59059b788 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -915,6 +915,7 @@ static bool disk_has_partitions(struct gendisk *disk)
 void disk_set_zoned(struct gendisk *disk, enum blk_zoned_model model)
 {
 	struct request_queue *q = disk->queue;
+	unsigned int old_model = q->limits.zoned;
 
 	switch (model) {
 	case BLK_ZONED_HM:
@@ -952,7 +953,7 @@ void disk_set_zoned(struct gendisk *disk, enum blk_zoned_model model)
 		 */
 		blk_queue_zone_write_granularity(q,
 						queue_logical_block_size(q));
-	} else {
+	} else if (old_model != BLK_ZONED_NONE) {
 		disk_clear_zone_settings(disk);
 	}
 }