Commit b49a0871 authored by Ming Lin's avatar Ming Lin Committed by Jens Axboe
Browse files

block: remove split code in blkdev_issue_{discard,write_same} 



The split code in blkdev_issue_{discard,write_same} can go away
now that any driver that cares does the split. We have to make
sure bio size doesn't overflow.

For discard, we set max discard sectors to (1<<31)>>9 to ensure
it doesn't overflow bi_size and hopefully it is of the proper
granularity as long as the granularity is a power of two.

Acked-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarMing Lin <ming.l@ssi.samsung.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 0e28997e

block/blk-lib.c

+11 −36
Original line number Diff line number Diff line
@@ -26,6 +26,13 @@ static void bio_batch_end_io(struct bio *bio) 
	bio_put(bio);

}



/*

 * Ensure that max discard sectors doesn't overflow bi_size and hopefully

 * it is of the proper granularity as long as the granularity is a power

 * of two.

 */

#define MAX_BIO_SECTORS ((1U << 31) >> 9)



/**

 * blkdev_issue_discard - queue a discard

 * @bdev:	blockdev to issue discard for
@@ -43,8 +50,6 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
	DECLARE_COMPLETION_ONSTACK(wait);

	struct request_queue *q = bdev_get_queue(bdev);

	int type = REQ_WRITE | REQ_DISCARD;

	unsigned int max_discard_sectors, granularity;

	int alignment;

	struct bio_batch bb;

	struct bio *bio;

	int ret = 0;
@@ -56,21 +61,6 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
	if (!blk_queue_discard(q))

		return -EOPNOTSUPP;



	/* Zero-sector (unknown) and one-sector granularities are the same.  */

	granularity = max(q->limits.discard_granularity >> 9, 1U);

	alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;



	/*

	 * Ensure that max_discard_sectors is of the proper

	 * granularity, so that requests stay aligned after a split.

	 */

	max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);

	max_discard_sectors -= max_discard_sectors % granularity;

	if (unlikely(!max_discard_sectors)) {

		/* Avoid infinite loop below. Being cautious never hurts. */

		return -EOPNOTSUPP;

	}



	if (flags & BLKDEV_DISCARD_SECURE) {

		if (!blk_queue_secdiscard(q))

			return -EOPNOTSUPP;
@@ -84,7 +74,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
	blk_start_plug(&plug);

	while (nr_sects) {

		unsigned int req_sects;

		sector_t end_sect, tmp;

		sector_t end_sect;



		bio = bio_alloc(gfp_mask, 1);

		if (!bio) {
@@ -92,21 +82,8 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
			break;

		}



		req_sects = min_t(sector_t, nr_sects, max_discard_sectors);



		/*

		 * If splitting a request, and the next starting sector would be

		 * misaligned, stop the discard at the previous aligned sector.

		 */

		req_sects = min_t(sector_t, nr_sects, MAX_BIO_SECTORS);

		end_sect = sector + req_sects;

		tmp = end_sect;

		if (req_sects < nr_sects &&

		    sector_div(tmp, granularity) != alignment) {

			end_sect = end_sect - alignment;

			sector_div(end_sect, granularity);

			end_sect = end_sect * granularity + alignment;

			req_sects = end_sect - sector;

		}



		bio->bi_iter.bi_sector = sector;

		bio->bi_end_io = bio_batch_end_io;
@@ -165,10 +142,8 @@ int blkdev_issue_write_same(struct block_device *bdev, sector_t sector, 
	if (!q)

		return -ENXIO;



	max_write_same_sectors = q->limits.max_write_same_sectors;



	if (max_write_same_sectors == 0)

		return -EOPNOTSUPP;

	/* Ensure that max_write_same_sectors doesn't overflow bi_size */

	max_write_same_sectors = UINT_MAX >> 9;



	atomic_set(&bb.done, 1);

	bb.error = 0;

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