From: Mike Snitzer <snitzer@redhat.com>
Date: Tue, 20 Jun 2017 23:14:30 +0000 (-0400)
Subject: dm io: fix duplicate bio completion due to missing ref count
X-Git-Tag: v5.15~11055^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=feb7695fe9fb83084aa29de0094774f4c9d4c9fc;p=platform%2Fkernel%2Flinux-starfive.git

dm io: fix duplicate bio completion due to missing ref count

If only a subset of the devices associated with multiple regions support
a given special operation (eg. DISCARD) then the dec_count() that is
used to set error for the region must increment the io->count.

Otherwise, when the dec_count() is called it can cause the dm-io
caller's bio to be completed multiple times.  As was reported against
the dm-mirror target that had mirror legs with a mix of discard
capabilities.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=196077
Reported-by: Zhang Yi <yizhan@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 3702e502466d..8d5ca30f6551 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -317,8 +317,8 @@ static void do_region(int op, int op_flags, unsigned region,
 	else if (op == REQ_OP_WRITE_SAME)
 		special_cmd_max_sectors = q->limits.max_write_same_sectors;
 	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES ||
-	     op == REQ_OP_WRITE_SAME)  &&
-	    special_cmd_max_sectors == 0) {
+	     op == REQ_OP_WRITE_SAME) && special_cmd_max_sectors == 0) {
+		atomic_inc(&io->count);
 		dec_count(io, region, -EOPNOTSUPP);
 		return;
 	}