[PATCH 06/14] block: use queue_limits_commit_update in queue_discard_max_store

[Christoph Hellwig]

Convert queue_discard_max_store to use queue_limits_commit_update to
check and update the max_discard_sectors limit and freeze the queue
before doing so to ensure we don't have requests in flight while
changing the limits.

Signed-off-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Damien Le Moal <dlemoal at kernel.org>
Reviewed-by: Hannes Reinecke <hare at suse.de>
---
 block/blk-sysfs.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 54e10604ddb1dd..8c8f69d8ba48ee 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -175,7 +175,9 @@ static ssize_t queue_discard_max_store(struct request_queue *q,
 				       const char *page, size_t count)
 {
 	unsigned long max_discard_bytes;
+	struct queue_limits lim;
 	ssize_t ret;
+	int err;
 
 	ret = queue_var_store(&max_discard_bytes, page, count);
 	if (ret < 0)
@@ -187,10 +189,14 @@ static ssize_t queue_discard_max_store(struct request_queue *q,
 	if ((max_discard_bytes >> SECTOR_SHIFT) > UINT_MAX)
 		return -EINVAL;
 
-	q->limits.max_user_discard_sectors = max_discard_bytes >> SECTOR_SHIFT;
-	q->limits.max_discard_sectors =
-		min_not_zero(q->limits.max_hw_discard_sectors,
-			     q->limits.max_user_discard_sectors);
+	blk_mq_freeze_queue(q);
+	lim = queue_limits_start_update(q);
+	lim.max_user_discard_sectors = max_discard_bytes >> SECTOR_SHIFT;
+	err = queue_limits_commit_update(q, &lim);
+	blk_mq_unfreeze_queue(q);
+
+	if (err)
+		return err;
 	return ret;
 }
 
-- 
2.39.2