block: ignore __blkdev_issue_discard() return value

__blkdev_issue_discard() always returns 0, making the error check
in blkdev_issue_discard() dead code.

In function blkdev_issue_discard() initialize ret = 0, remove ret
assignment from __blkdev_issue_discard(), rely on bio == NULL check to
call submit_bio_wait(), preserve submit_bio_wait() error handling, and
preserve -EOPNOTSUPP to 0 mapping.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Chaitanya Kulkarni <ckulkarnilinux@gmail.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: ChaitanayaKulkarni

block/blk-lib.c

@@ -87,11 +87,11 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 {
 	struct bio *bio = NULL;
 	struct blk_plug plug;
-	int ret;
+	int ret = 0;
 
 	blk_start_plug(&plug);
-	ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, &bio);
-	if (!ret && bio) {
+	__blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, &bio);
+	if (bio) {
 		ret = submit_bio_wait(bio);
 		if (ret == -EOPNOTSUPP)
 			ret = 0;