block: freeze the queue in queue_attr_store

queue_attr_store updates attributes used to control generating I/O, and
can cause malformed bios if changed with I/O in flight.  Freeze the queue
in common code instead of adding it to almost every attribute.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240617060532.127975-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -4631,13 +4631,15 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 	int ret;
 	unsigned long i;
 
+	if (WARN_ON_ONCE(!q->mq_freeze_depth))
+		return -EINVAL;
+
 	if (!set)
 		return -EINVAL;
 
 	if (q->nr_requests == nr)
 		return 0;
 
-	blk_mq_freeze_queue(q);
 	blk_mq_quiesce_queue(q);
 
 	ret = 0;
@@ -4671,7 +4673,6 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 	}
 
 	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q);
 
 	return ret;
 }

block/blk-sysfs.c

@@ -189,12 +189,9 @@ static ssize_t queue_discard_max_store(struct request_queue *q,
 	if ((max_discard_bytes >> SECTOR_SHIFT) > UINT_MAX)
 		return -EINVAL;
 
-	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;
@@ -241,11 +238,9 @@ queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
 	if (ret < 0)
 		return ret;
 
-	blk_mq_freeze_queue(q);
 	lim = queue_limits_start_update(q);
 	lim.max_user_sectors = max_sectors_kb << 1;
 	err = queue_limits_commit_update(q, &lim);
-	blk_mq_unfreeze_queue(q);
 	if (err)
 		return err;
 	return ret;
@@ -585,13 +580,11 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
 	 * ends up either enabling or disabling wbt completely. We can't
 	 * have IO inflight if that happens.
 	 */
-	blk_mq_freeze_queue(q);
 	blk_mq_quiesce_queue(q);
 
 	wbt_set_min_lat(q, val);
 
 	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q);
 
 	return count;
 }
@@ -722,9 +715,11 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr,
 	if (!entry->store)
 		return -EIO;
 
+	blk_mq_freeze_queue(q);
 	mutex_lock(&q->sysfs_lock);
 	res = entry->store(q, page, length);
 	mutex_unlock(&q->sysfs_lock);
+	blk_mq_unfreeze_queue(q);
 	return res;
 }