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

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>

1 files changed, 3 insertions, 1 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 49af34bf2119..7aeef19704f2 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2162,7 +2162,9 @@ 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];
 
                 printk(KERN_ERR