block: add cond_resched() to potentially long running ioctl discard loop
When mkfs issues a full device discard and the device only
supports discards of a smallish size, we can loop in
blkdev_issue_discard() for a long time. If preempt isn't enabled,
this can turn into a softlock situation and the kernel will
start complaining.
Add an explicit cond_resched() at the end of the loop to avoid
that.
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 2da76c9..97a733c 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -119,6 +119,14 @@
atomic_inc(&bb.done);
submit_bio(type, bio);
+
+ /*
+ * We can loop for a long time in here, if someone does
+ * full device discards (like mkfs). Be nice and allow
+ * us to schedule out to avoid softlocking if preempt
+ * is disabled.
+ */
+ cond_resched();
}
blk_finish_plug(&plug);