From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 14 Aug 2018 10:52:40 -0600
Subject: block: don't warn for flush on read-only device
Git-commit: b089cfd95d32638335c551651a8e00fd2c4edb0b
Patch-mainline: v4.19-rc1
References: bsc#1107756

Don't warn for a flush issued to a read-only device. It's not strictly
a writable command, as it doesn't change any on-media data by itself.

Reported-by: Stefan Agner <stefan@agner.ch>
Fixes: 721c7fc701c7 ("block: fail op_is_write() requests to read-only partitions")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 block/blk-core.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2173,7 +2173,9 @@ static inline bool should_fail_request(s
 
 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
 {
-	if (part->policy && op_is_write(bio_op(bio))) {
+	const int op = bio_op(bio);
+
+	if (part->policy && (op_is_write(op) && !op_is_flush(op))) {
 		char b[BDEVNAME_SIZE];
 
 		WARN_ONCE(1,