block: don't warn when doing fsync on read-only devices

Mikulas Patocka · axboe · commit 8b2ded1c94c0 · 2018-09-05T16:14:36.000-06:00
It is possible to call fsync on a read-only handle (for example, fsck.ext2 does it when doing read-only check), and this call results in kernel warning. The patch b089cfd ("block: don't warn for flush on read-only device") attempted to disable the warning, but it is buggy and it doesn't (op_is_flush tests flags, but bio_op strips off the flags). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Fixes: 721c7fc ("block: fail op_is_write() requests to read-only partitions") Cc: stable@vger.kernel.org # 4.18 Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-core.c b/block/blk-core.c
@@ -2163,9 +2163,12 @@ static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
 {
 	const int op = bio_op(bio);
 
-	if (part->policy && (op_is_write(op) && !op_is_flush(op))) {
+	if (part->policy && op_is_write(op)) {
 		char b[BDEVNAME_SIZE];
 
+		if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
+			return false;
+
 		WARN_ONCE(1,
 		       "generic_make_request: Trying to write "
 			"to read-only block-device %s (partno %d)\n",
