[PATCH AUTOSEL 6.10 114/121] block: factor out a blk_write_zeroes_limit helper

Sasha Levin
2024-08-01T00:18:20Z

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit 73a768d5f95533574bb8ace34eb683a88c40509e ]

Contrary to the comment in __blkdev_issue_write_zeroes, nothing here
checks for a potential bi_size overflow. Add a helper mirroring
the secure erase code for the check.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240701165219.1571322-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
block/blk-lib.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 442da9dad0421..297bcf6896930 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -103,24 +103,28 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
}
EXPORT_SYMBOL(blkdev_issue_discard);

+static sector_t bio_write_zeroes_limit(struct block_device *bdev)
+{
+ sector_t bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
+
+ return min(bdev_write_zeroes_sectors(bdev),
+ (UINT_MAX >> SECTOR_SHIFT) & ~bs_mask);
+}
+
static int __blkdev_issue_write_zeroes(struct block_device *bdev,
sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
struct bio **biop, unsigned flags)
{
struct bio *bio = *biop;
- unsigned int max_sectors;

if (bdev_read_only(bdev))
return -EPERM;
-
- /* Ensure that max_sectors doesn't overflow bi_size */
- max_sectors = bdev_write_zeroes_sectors(bdev);
-
- if (max_sectors == 0)
+ if (!bdev_write_zeroes_sectors(bdev))
return -EOPNOTSUPP;

while (nr_sects) {
- unsigned int len = min_t(sector_t, nr_sects, max_sectors);
+ unsigned int len = min_t(sector_t, nr_sects,
+ bio_write_zeroes_limit(bdev));

bio = blk_next_bio(bio, bdev, 0, REQ_OP_WRITE_ZEROES, gfp_mask);
bio->bi_iter.bi_sector = sector;
--
2.43.0