block: don't warn for flush on read-only device

[ 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>

diff --git a/block/blk-core.c b/block/blk-core.c
index 1646ea85dadeb36f3a269d1ece61b9a3c782ed57..746a5eac45410c8a8722543f0a739b7686bd7068 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2159,7 +2159,9 @@ static inline bool should_fail_request(struct hd_struct *part,
 
 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,