From: Geert Uytterhoeven Date: Mon, 4 Nov 2013 13:00:06 +0000 (+0100) Subject: block: Do not call sector_div() with a 64-bit divisor X-Git-Tag: drm-fsl-dcu-for-next~6399^2~7 X-Git-Url: http://git.agner.ch/gitweb/?a=commitdiff_plain;h=97597dc08f58e25bc74154b7d1c387a4c0432950;p=linux-drm-fsl-dcu.git 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 ea077b1b96e073eac5c3c5590529e964767fc5f7 ("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 Signed-off-by: Jens Axboe --- diff --git a/block/blk-lib.c b/block/blk-lib.c index d6f50d572565..9b5b561cb928 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -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;