block: eliminate potential for infinite loop in blkdev_issue_discard

[pandora-kernel.git] / block / blk-lib.c

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 78e627e..64974b1 100644 (file)
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -59,7 +59,10 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
         * granularity
         */
        max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
-       if (q->limits.discard_granularity) {
+       if (!unlikely(!max_discard_sectors)) {
+               /* Avoid infinite loop below. Being cautious never hurts. */
+               return -EOPNOTSUPP;
+       } else if (q->limits.discard_granularity) {
                unsigned int disc_sects = q->limits.discard_granularity >> 9;
 
                max_discard_sectors &= ~(disc_sects - 1);