md/raid10: Split handle_read_error out from raid10d.

raid10d() is too big and is about to get bigger, so split
handle_read_error() out as a separate function.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid10.c

@@ -1618,43 +1618,16 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 	}
 }
 
-static void raid10d(mddev_t *mddev)
+static void handle_read_error(mddev_t *mddev, r10bio_t *r10_bio)
 {
-	r10bio_t *r10_bio;
+	int slot = r10_bio->read_slot;
+	int mirror = r10_bio->devs[slot].devnum;
 	struct bio *bio;
-	unsigned long flags;
 	conf_t *conf = mddev->private;
-	struct list_head *head = &conf->retry_list;
 	mdk_rdev_t *rdev;
-	struct blk_plug plug;
-
-	md_check_recovery(mddev);
-
-	blk_start_plug(&plug);
-	for (;;) {
 	char b[BDEVNAME_SIZE];
+	unsigned long do_sync;
 
-		flush_pending_writes(conf);
-
-		spin_lock_irqsave(&conf->device_lock, flags);
-		if (list_empty(head)) {
-			spin_unlock_irqrestore(&conf->device_lock, flags);
-			break;
-		}
-		r10_bio = list_entry(head->prev, r10bio_t, retry_list);
-		list_del(head->prev);
-		conf->nr_queued--;
-		spin_unlock_irqrestore(&conf->device_lock, flags);
-
-		mddev = r10_bio->mddev;
-		conf = mddev->private;
-		if (test_bit(R10BIO_IsSync, &r10_bio->state))
-			sync_request_write(mddev, r10_bio);
-		else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
-			recovery_request_write(mddev, r10_bio);
-		else {
-			int slot = r10_bio->read_slot;
-			int mirror = r10_bio->devs[slot].devnum;
 	/* we got a read error. Maybe the drive is bad.  Maybe just
 	 * the block and we can fix it.
 	 * We freeze all other IO, and try reading the block from
@@ -1678,12 +1651,14 @@ static void raid10d(mddev_t *mddev)
 		printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
 		       " read error for block %llu\n",
 		       mdname(mddev),
-				       bdevname(bio->bi_bdev,b),
+		       bdevname(bio->bi_bdev, b),
 		       (unsigned long long)r10_bio->sector);
 		raid_end_bio_io(r10_bio);
 		bio_put(bio);
-			} else {
-				const unsigned long do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
+		return;
+	}
+
+	do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
 	bio_put(bio);
 	slot = r10_bio->read_slot;
 	rdev = conf->mirrors[mirror].rdev;
@@ -1704,8 +1679,42 @@ static void raid10d(mddev_t *mddev)
 	bio->bi_private = r10_bio;
 	bio->bi_end_io = raid10_end_read_request;
 	generic_make_request(bio);
+}
+
+static void raid10d(mddev_t *mddev)
+{
+	r10bio_t *r10_bio;
+	unsigned long flags;
+	conf_t *conf = mddev->private;
+	struct list_head *head = &conf->retry_list;
+	struct blk_plug plug;
+
+	md_check_recovery(mddev);
+
+	blk_start_plug(&plug);
+	for (;;) {
+
+		flush_pending_writes(conf);
+
+		spin_lock_irqsave(&conf->device_lock, flags);
+		if (list_empty(head)) {
+			spin_unlock_irqrestore(&conf->device_lock, flags);
+			break;
 		}
-		}
+		r10_bio = list_entry(head->prev, r10bio_t, retry_list);
+		list_del(head->prev);
+		conf->nr_queued--;
+		spin_unlock_irqrestore(&conf->device_lock, flags);
+
+		mddev = r10_bio->mddev;
+		conf = mddev->private;
+		if (test_bit(R10BIO_IsSync, &r10_bio->state))
+			sync_request_write(mddev, r10_bio);
+		else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
+			recovery_request_write(mddev, r10_bio);
+		else
+			handle_read_error(mddev, r10_bio);
+
 		cond_resched();
 		if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
 			md_check_recovery(mddev);