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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Stefan Agner <stefan@agner.ch>,
        Jens Axboe <axboe@kernel.dk>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 082/197] block: dont warn for flush on read-only device
Date:   Thu, 13 Sep 2018 15:30:31 +0200
Message-Id: <20180913131844.815669025@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jens Axboe <axboe@kernel.dk>

[ Upstream commit b089cfd95d32638335c551651a8e00fd2c4edb0b ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 block/blk-core.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2159,7 +2159,9 @@ 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,