Commit 744889b7 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: don't deal with discard limit in blkdev_issue_discard() 



blk_queue_split() does respect this limit via bio splitting, so no
need to do that in blkdev_issue_discard(), then we can align to
normal bio submit(bio_add_page() & submit_bio()).

More importantly, this patch fixes one issue introduced in a22c4d7e
("block: re-add discard_granularity and alignment checks"), in which
zero discard bio may be generated in case of zero alignment.

Fixes: a22c4d7e ("block: re-add discard_granularity and alignment checks")
Cc: stable@vger.kernel.org
Cc: Ming Lin <ming.l@ssi.samsung.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Xiao Ni <xni@redhat.com>
Tested-by: default avatarMariusz Dabrowski <mariusz.dabrowski@intel.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7a7080b5

block/blk-lib.c

+2 −26
Original line number Diff line number Diff line
@@ -29,9 +29,7 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
{

	struct request_queue *q = bdev_get_queue(bdev);

	struct bio *bio = *biop;

	unsigned int granularity;

	unsigned int op;

	int alignment;

	sector_t bs_mask;



	if (!q)
@@ -54,38 +52,16 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
	if ((sector | nr_sects) & bs_mask)

		return -EINVAL;



	/* 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;



	while (nr_sects) {

		unsigned int req_sects;

		sector_t end_sect, tmp;

		unsigned int req_sects = nr_sects;

		sector_t end_sect;



		/*

		 * Issue in chunks of the user defined max discard setting,

		 * ensuring that bi_size doesn't overflow

		 */

		req_sects = min_t(sector_t, nr_sects,

					q->limits.max_discard_sectors);

		if (!req_sects)

			goto fail;

		if (req_sects > UINT_MAX >> 9)

			req_sects = UINT_MAX >> 9;



		/*

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

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

		 */

		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 = next_bio(bio, 0, gfp_mask);

		bio->bi_iter.bi_sector = sector;

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