Commit a26a339a authored by Yu Kuai's avatar Yu Kuai Committed by Jens Axboe
Browse files

brd: fix discard end sector 



brd_do_discard() just aligned start sector to page, this can only work
if the discard size if at least one page. For example:

blkdiscard /dev/ram0 -o 5120 -l 1024

In this case, size = (1024 - (8192 - 5120)), which is a huge value.

Fix the problem by round_down() the end sector.

Fixes: 9ead7efc ("brd: implement discard support")
Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250506061756.2970934-4-yukuai1@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d4099f88

drivers/block/brd.c

+6 −3
Original line number Diff line number Diff line
@@ -167,18 +167,21 @@ static void brd_free_one_page(struct rcu_head *head) 
static void brd_do_discard(struct brd_device *brd, sector_t sector, u32 size)

{

	sector_t aligned_sector = round_up(sector, PAGE_SECTORS);

	sector_t aligned_end = round_down(

			sector + (size >> SECTOR_SHIFT), PAGE_SECTORS);

	struct page *page;



	size -= (aligned_sector - sector) * SECTOR_SIZE;

	if (aligned_end <= aligned_sector)

		return;



	xa_lock(&brd->brd_pages);

	while (size >= PAGE_SIZE && aligned_sector < rd_size * 2) {

	while (aligned_sector < aligned_end && aligned_sector < rd_size * 2) {

		page = __xa_erase(&brd->brd_pages, aligned_sector >> PAGE_SECTORS_SHIFT);

		if (page) {

			call_rcu(&page->rcu_head, brd_free_one_page);

			brd->brd_nr_pages--;

		}

		aligned_sector += PAGE_SECTORS;

		size -= PAGE_SIZE;

	}

	xa_unlock(&brd->brd_pages);

}