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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: 9ead7efc6f ("brd: implement discard support")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250506061756.2970934-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Yu Kuai 2025-05-06 14:17:56 +08:00 committed by Jens Axboe
parent d4099f8893
commit a26a339a65
1 changed files with 6 additions and 3 deletions
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9
drivers/block/brd.c
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@ -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);
}