dm flakey: error READ bios during the down_interval

When the corrupt_bio_byte feature was introduced it caused READ bios to
no longer be errored with -EIO during the down_interval.  This had to do
with the complexity of needing to submit READs if the corrupt_bio_byte
feature was used.

Fix it so READ bios are properly errored with -EIO; doing so early in
flakey_map() as long as there isn't a match for the corrupt_bio_byte
feature.

Fixes: a3998799fb4df ("dm flakey: add corrupt_bio_byte feature")
Reported-by: Akira Hayakawa <ruby.wktk@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org

drivers/md/dm-flakey.c

@@ -289,10 +289,16 @@ static int flakey_map(struct dm_target *ti, struct bio *bio)
 		pb->bio_submitted = true;
 
 		/*
-		 * Map reads as normal.
+		 * Map reads as normal only if corrupt_bio_byte set.
 		 */
-		if (bio_data_dir(bio) == READ)
-			goto map_bio;
+		if (bio_data_dir(bio) == READ) {
+			/* If flags were specified, only corrupt those that match. */
+			if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
+			    all_corrupt_bio_flags_match(bio, fc))
+				goto map_bio;
+			else
+				return -EIO;
+		}
 
 		/*
 		 * Drop writes?
@@ -330,12 +336,13 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
 
 	/*
 	 * Corrupt successful READs while in down state.
-	 * If flags were specified, only corrupt those that match.
 	 */
-	if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
-	    (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
-	    all_corrupt_bio_flags_match(bio, fc))
-		corrupt_bio_data(bio, fc);
+	if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
+		if (fc->corrupt_bio_byte)
+			corrupt_bio_data(bio, fc);
+		else
+			return -EIO;
+	}
 
 	return error;
 }