block: Do not call sector_div() with a 64-bit divisor (97597dc0) · Commits · 戴 / test

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 ("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:

Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-lib.c

+4 −6

Original line number	Diff line number	Diff line
		@@ -43,8 +43,8 @@ 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;
		sector_t max_discard_sectors;
		sector_t granularity, alignment;
		unsigned int max_discard_sectors, granularity;
		int alignment;
		struct bio_batch bb;
		struct bio *bio;
		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. */
		granularity = max(q->limits.discard_granularity >> 9, 1U);
		alignment = bdev_discard_alignment(bdev) >> 9;
		alignment = sector_div(alignment, granularity);
		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);
		sector_div(max_discard_sectors, granularity);
		max_discard_sectors *= granularity;
		max_discard_sectors -= max_discard_sectors % granularity;
		if (unlikely(!max_discard_sectors)) {
		/* Avoid infinite loop below. Being cautious never hurts. */
		return -EOPNOTSUPP;

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