[PATCH] md: keep better track of dev/array size when assembling md arrays

Move the checks - that dev size is never less than array size - into
bind_rdev_to_array to make sure it always happens properly (there is one place
where currently it doesn't).

Also reject any superblock which claims an array size smaller than the device
in question can hold.
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/md.c

@@ -695,6 +695,10 @@ static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version
 	}
 	rdev->size = calc_dev_size(rdev, sb->chunk_size);
 
+	if (rdev->size < sb->size && sb->level > 1)
+		/* "this cannot possibly happen" ... */
+		ret = -EINVAL;
+
  abort:
 	return ret;
 }
@@ -1039,6 +1043,9 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
 	rdev->size = le64_to_cpu(sb->data_size)/2;
 	if (le32_to_cpu(sb->chunksize))
 		rdev->size &= ~((sector_t)le32_to_cpu(sb->chunksize)/2 - 1);
+
+	if (le32_to_cpu(sb->size) > rdev->size*2)
+		return -EINVAL;
 	return 0;
 }
 
@@ -1224,6 +1231,14 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
 		MD_BUG();
 		return -EINVAL;
 	}
+	/* make sure rdev->size exceeds mddev->size */
+	if (rdev->size && (mddev->size == 0 || rdev->size < mddev->size)) {
+		if (mddev->pers)
+			/* Cannot change size, so fail */
+			return -ENOSPC;
+		else
+			mddev->size = rdev->size;
+	}
 	same_pdev = match_dev_unit(mddev, rdev);
 	if (same_pdev)
 		printk(KERN_WARNING
@@ -2898,12 +2913,6 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
 		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
 			set_bit(WriteMostly, &rdev->flags);
 
-		err = bind_rdev_to_array(rdev, mddev);
-		if (err) {
-			export_rdev(rdev);
-			return err;
-		}
-
 		if (!mddev->persistent) {
 			printk(KERN_INFO "md: nonpersistent superblock ...\n");
 			rdev->sb_offset = rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
@@ -2911,8 +2920,11 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
 			rdev->sb_offset = calc_dev_sboffset(rdev->bdev);
 		rdev->size = calc_dev_size(rdev, mddev->chunk_size);
 
-		if (!mddev->size || (mddev->size > rdev->size))
-			mddev->size = rdev->size;
+		err = bind_rdev_to_array(rdev, mddev);
+		if (err) {
+			export_rdev(rdev);
+			return err;
+		}
 	}
 
 	return 0;
@@ -2984,15 +2996,6 @@ static int hot_add_disk(mddev_t * mddev, dev_t dev)
 	size = calc_dev_size(rdev, mddev->chunk_size);
 	rdev->size = size;
 
-	if (size < mddev->size) {
-		printk(KERN_WARNING 
-			"%s: disk size %llu blocks < array size %llu\n",
-			mdname(mddev), (unsigned long long)size,
-			(unsigned long long)mddev->size);
-		err = -ENOSPC;
-		goto abort_export;
-	}
-
 	if (test_bit(Faulty, &rdev->flags)) {
 		printk(KERN_WARNING 
 			"md: can not hot-add faulty %s disk to %s!\n",
@@ -3002,7 +3005,9 @@ static int hot_add_disk(mddev_t * mddev, dev_t dev)
 	}
 	clear_bit(In_sync, &rdev->flags);
 	rdev->desc_nr = -1;
-	bind_rdev_to_array(rdev, mddev);
+	err = bind_rdev_to_array(rdev, mddev);
+	if (err)
+		goto abort_export;
 
 	/*
 	 * The rest should better be atomic, we can have disk failures