dm flakey: fix logic when corrupting a bio

If "corrupt_bio_byte" is set to corrupt reads and corrupt_bio_flags is
used, dm-flakey would erroneously return all writes as errors. Likewise,
if "corrupt_bio_byte" is set to corrupt writes, dm-flakey would return
errors for all reads.

Fix the logic so that if fc->corrupt_bio_byte is non-zero, dm-flakey
will not abort reads on writes with an error.

Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-flakey.c

@@ -365,9 +365,11 @@ static int flakey_map(struct dm_target *ti, struct bio *bio)
 		/*
 		 * Corrupt matching writes.
 		 */
-		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
-			if (all_corrupt_bio_flags_match(bio, fc))
-				corrupt_bio_data(bio, fc);
+		if (fc->corrupt_bio_byte) {
+			if (fc->corrupt_bio_rw == WRITE) {
+				if (all_corrupt_bio_flags_match(bio, fc))
+					corrupt_bio_data(bio, fc);
+			}
 			goto map_bio;
 		}
 
@@ -393,13 +395,14 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio,
 		return DM_ENDIO_DONE;
 
 	if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
-		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
-		    all_corrupt_bio_flags_match(bio, fc)) {
-			/*
-			 * Corrupt successful matching READs while in down state.
-			 */
-			corrupt_bio_data(bio, fc);
-
+		if (fc->corrupt_bio_byte) {
+			if ((fc->corrupt_bio_rw == READ) &&
+			    all_corrupt_bio_flags_match(bio, fc)) {
+				/*
+				 * Corrupt successful matching READs while in down state.
+				 */
+				corrupt_bio_data(bio, fc);
+			}
 		} else if (!test_bit(DROP_WRITES, &fc->flags) &&
 			   !test_bit(ERROR_WRITES, &fc->flags)) {
 			/*