From b88aef36b87c9787a4db724923ec4f57dfd513f3 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Tue, 3 Jul 2018 13:34:22 -0400 Subject: [PATCH] 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 Tested-by: Zdenek Kabelac Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe --- block/blk-lib.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/block/blk-lib.c b/block/blk-lib.c index 8faa70f26fcd..d1b9dd03da25 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -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);