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Commit 97597dc0 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Jens Axboe
Browse files

block: Do not call sector_div() with a 64-bit divisor 



do_div() (called by sector_div() if CONFIG_LBDAF=y) is meant for divisions
of 64-bit number by 32-bit numbers.  Passing 64-bit divisor types caused
issues in the past on 32-bit platforms, cfr. commit
ea077b1b ("m68k: Truncate base in
do_div()").

As queue_limits.max_discard_sectors and .discard_granularity are unsigned
int, max_discard_sectors and granularity should be unsigned int.
As bdev_discard_alignment() returns int, alignment should be int.
Now 2 calls to sector_div() can be replaced by 32-bit arithmetic:
  - The 64-bit modulo operation can become a 32-bit modulo operation,
  - The 64-bit division and multiplication can be replaced by a 32-bit
    modulo operation and a subtraction.

Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent f8c5e944

block/blk-lib.c

+4 −6
Original line number Original line Diff line number Diff line
@@ -43,8 +43,8 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 
	DECLARE_COMPLETION_ONSTACK(wait);

	DECLARE_COMPLETION_ONSTACK(wait);

	struct request_queue *q = bdev_get_queue(bdev);

	struct request_queue *q = bdev_get_queue(bdev);

	int type = REQ_WRITE | REQ_DISCARD;

	int type = REQ_WRITE | REQ_DISCARD;

	sector_t max_discard_sectors;

	unsigned int max_discard_sectors, granularity;

	sector_t granularity, alignment;

	int alignment;

	struct bio_batch bb;

	struct bio_batch bb;

	struct bio *bio;

	struct bio *bio;

	int ret = 0;

	int ret = 0;
@@ -58,16 +58,14 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, 




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

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

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

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

	alignment = bdev_discard_alignment(bdev) >> 9;

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

	alignment = sector_div(alignment, granularity);





	/*

	/*

	 * Ensure that max_discard_sectors is of the proper

	 * Ensure that max_discard_sectors is of the proper

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

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

	 */

	 */

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

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

	sector_div(max_discard_sectors, granularity);

	max_discard_sectors -= max_discard_sectors % granularity;

	max_discard_sectors *= granularity;

	if (unlikely(!max_discard_sectors)) {

	if (unlikely(!max_discard_sectors)) {

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

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

		return -EOPNOTSUPP;

		return -EOPNOTSUPP;