[PATCH] md: return a non-zero error to bi_end_io as appropriate in raid5

Currently raid5 depends on clearing the BIO_UPTODATE flag to signal an error
to higher levels.  While this should be sufficient, it is safer to explicitly
set the error code as well - less room for confusion.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/raid5.c

@@ -1818,7 +1818,9 @@ static void handle_stripe5(struct stripe_head *sh)
 		return_bi = bi->bi_next;
 		bi->bi_next = NULL;
 		bi->bi_size = 0;
-		bi->bi_end_io(bi, bytes, 0);
+		bi->bi_end_io(bi, bytes,
+			      test_bit(BIO_UPTODATE, &bi->bi_flags)
+			        ? 0 : -EIO);
 	}
 	for (i=disks; i-- ;) {
 		int rw;
@@ -2359,7 +2361,9 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 		return_bi = bi->bi_next;
 		bi->bi_next = NULL;
 		bi->bi_size = 0;
-		bi->bi_end_io(bi, bytes, 0);
+		bi->bi_end_io(bi, bytes,
+			      test_bit(BIO_UPTODATE, &bi->bi_flags)
+			        ? 0 : -EIO);
 	}
 	for (i=disks; i-- ;) {
 		int rw;
@@ -2859,7 +2863,9 @@ static int make_request(request_queue_t *q, struct bio * bi)
 		if ( rw == WRITE )
 			md_write_end(mddev);
 		bi->bi_size = 0;
-		bi->bi_end_io(bi, bytes, 0);
+		bi->bi_end_io(bi, bytes,
+			      test_bit(BIO_UPTODATE, &bi->bi_flags)
+			        ? 0 : -EIO);
 	}
 	return 0;
 }
@@ -3127,7 +3133,9 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
 		int bytes = raid_bio->bi_size;
 
 		raid_bio->bi_size = 0;
-		raid_bio->bi_end_io(raid_bio, bytes, 0);
+		raid_bio->bi_end_io(raid_bio, bytes,
+			      test_bit(BIO_UPTODATE, &raid_bio->bi_flags)
+			        ? 0 : -EIO);
 	}
 	if (atomic_dec_and_test(&conf->active_aligned_reads))
 		wake_up(&conf->wait_for_stripe);