6.15-stable review patch. If anyone has any objections, please let me know.
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From: Yu Kuai yukuai3@huawei.com
[ Upstream commit a26a339a654b9403f0ee1004f1db4c2b2a355460 ]
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: 9ead7efc6f3f ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/brd.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 9549cd71e083b..02fa8106ef549 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -225,18 +225,21 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page, 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) { __free_page(page); brd->brd_nr_pages--; } aligned_sector += PAGE_SECTORS; - size -= PAGE_SIZE; } xa_unlock(&brd->brd_pages); }