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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>
hifive-unleashed-5.1
Mikulas Patocka 2018-07-03 13:34:22 -04:00 committed by Jens Axboe
parent c137969bd4
commit b88aef36b8
1 changed files with 10 additions and 0 deletions
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10
block/blk-lib.c
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@ -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);