diff mbox

block: fix infinite loop if the device loses discard capability

Message ID alpine.LRH.2.02.1807031332250.22443@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive)
State Accepted, archived
Delegated to: Mike Snitzer
Headers show

Commit Message

Mikulas Patocka July 3, 2018, 5:34 p.m. UTC 
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

---
 block/blk-lib.c |   10 ++++++++++
 1 file changed, 10 insertions(+)


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Comments

Jens Axboe July 6, 2018, 1:50 p.m. UTC | #1 
On 7/3/18 11:34 AM, Mikulas Patocka wrote:
> 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.

Applied, thanks.
diff mbox

Patch

Index: linux-2.6/block/blk-lib.c
===================================================================
--- linux-2.6.orig/block/blk-lib.c	2018-06-18 01:08:49.500000000 +0200
+++ linux-2.6/block/blk-lib.c	2018-06-29 20:09:27.670000000 +0200
@@ -68,6 +68,8 @@  int __blkdev_issue_discard(struct block_
 		 */
 		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_
 
 	*biop = bio;
 	return 0;
+
+fail:
+	if (bio) {
+		submit_bio_wait(bio);
+		bio_put(bio);
+	}
+	*biop = NULL;
+	return -EOPNOTSUPP;
 }
 EXPORT_SYMBOL(__blkdev_issue_discard);