Commit b88aef36 authored Jul 03, 2018 by Mikulas Patocka Committed by Jens Axboe Jul 09, 2018

block: fix infinite loop if the device loses discard capability



If __blkdev_issue_discard is in progress and a device mapper device is
reloaded with a table that doesn't support discard,
q->limits.max_discard_sectors is set to zero. This results in infinite
loop in __blkdev_issue_discard.

This patch checks if max_discard_sectors is zero and aborts with
-EOPNOTSUPP.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Tested-by: Zdenek Kabelac <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent c137969b

block/blk-lib.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -68,6 +68,8 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
		*/
		req_sects = min_t(sector_t, nr_sects,
		q->limits.max_discard_sectors);
		if (!req_sects)
		goto fail;
		if (req_sects > UINT_MAX >> 9)
		req_sects = UINT_MAX >> 9;

		@@ -105,6 +107,14 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,

		*biop = bio;
		return 0;

		fail:
		if (bio) {
		submit_bio_wait(bio);
		bio_put(bio);
		}
		*biop = NULL;
		return -EOPNOTSUPP;
		}
		EXPORT_SYMBOL(__blkdev_issue_discard);