Merge branch 'for-linus' of git://neil.brown.name/md

* 'for-linus' of git://neil.brown.name/md:
md: Ensure an md array never has too many devices.
md: Fix a bug in linear.c causing which_dev() to return the wrong device.
md: Allow read error in a single drive raid1 to be passed up.

drivers/md/linear.c

···
 {
 	dev_info_t *hash;
 	linear_conf_t *conf = mddev_to_conf(mddev);
+	sector_t idx = sector >> conf->sector_shift;
 
 	/*
 	 * sector_div(a,b) returns the remainer and sets a to a/b
 	 */
-	sector >>= conf->sector_shift;
-	(void)sector_div(sector, conf->spacing);
-	hash = conf->hash_table[sector];
+	(void)sector_div(idx, conf->spacing);
+	hash = conf->hash_table[idx];
 
 	while (sector >= hash->num_sectors + hash->start_sector)
 		hash++;

drivers/md/md.c

···
 		if (find_rdev_nr(mddev, rdev->desc_nr))
 			return -EBUSY;
 	}
+	if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
+		printk(KERN_WARNING "md: %s: array is limited to %d devices\n",
+		       mdname(mddev), mddev->max_disks);
+		return -EBUSY;
+	}
 	bdevname(rdev->bdev,b);
 	while ( (s=strchr(b, '/')) != NULL)
 		*s = '!';
···
 
 	i = 0;
 	rdev_for_each(rdev, tmp, mddev) {
+		if (rdev->desc_nr >= mddev->max_disks ||
+		    i > mddev->max_disks) {
+			printk(KERN_WARNING
+			       "md: %s: %s: only %d devices permitted\n",
+			       mdname(mddev), bdevname(rdev->bdev, b),
+			       mddev->max_disks);
+			kick_rdev_from_array(rdev);
+			continue;
+		}
 		if (rdev != freshest)
 			if (super_types[mddev->major_version].
 			    validate_super(mddev, rdev)) {
···
 	 * noticed in interrupt contexts ...
 	 */
 
-	if (rdev->desc_nr == mddev->max_disks) {
-		printk(KERN_WARNING "%s: can not hot-add to full array!\n",
-			mdname(mddev));
-		err = -EBUSY;
-		goto abort_unbind_export;
-	}
-
 	rdev->raid_disk = -1;
 
 	md_update_sb(mddev, 1);
···
 	md_wakeup_thread(mddev->thread);
 	md_new_event(mddev);
 	return 0;
-
-abort_unbind_export:
-	unbind_rdev_from_array(rdev);
 
 abort_export:
 	export_rdev(rdev);

drivers/md/raid1.c

···
 			}
 
 			bio = r1_bio->bios[r1_bio->read_disk];
-			if ((disk=read_balance(conf, r1_bio)) == -1) {
+			if ((disk=read_balance(conf, r1_bio)) == -1 ||
+			    disk == r1_bio->read_disk) {
 				printk(KERN_ALERT "raid1: %s: unrecoverable I/O"
 				       " read error for block %llu\n",
 				       bdevname(bio->bi_bdev,b),