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@xxxxxxxxxx>
Tested-by: Zdenek Kabelac <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
block/blk-lib.c | 10 ++++++++++
1 file changed, 10 insertions(+)
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);
