block: Remove REQ_OP_ZONE_RESET plugging

REQ_OP_ZONE_RESET operations cannot be merged as these bios and requests
do not have a size and are never sequential due to the zone start sector
position required for their execution. As a result, there is no point in
using a plug around blkdev_reset_zones() bio issuing loop. This patch
removes this unnecessary plugging.
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Javier González <javier@javigon.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-zoned.c

@@ -258,7 +258,6 @@ int blkdev_reset_zones(struct block_device *bdev,
 	sector_t zone_sectors;
 	sector_t end_sector = sector + nr_sectors;
 	struct bio *bio = NULL;
-	struct blk_plug plug;
 	int ret;
 
 	if (!blk_queue_is_zoned(q))
@@ -283,7 +282,6 @@ int blkdev_reset_zones(struct block_device *bdev,
 	    end_sector != bdev->bd_part->nr_sects)
 		return -EINVAL;
 
-	blk_start_plug(&plug);
 	while (sector < end_sector) {
 
 		bio = blk_next_bio(bio, 0, gfp_mask);
@@ -301,8 +299,6 @@ int blkdev_reset_zones(struct block_device *bdev,
 	ret = submit_bio_wait(bio);
 	bio_put(bio);
 
-	blk_finish_plug(&plug);
-
 	return ret;
 }
 EXPORT_SYMBOL_GPL(blkdev_reset_zones);