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Commit d3b178ad authored by Goldwyn Rodrigues's avatar Goldwyn Rodrigues Committed by NeilBrown
Browse files

md: Skip cluster setup for dm-raid 

There is a bug that the bitmap superblock isn't initialised properly for
dm-raid, so a new field can have garbage in new fields.
(dm-raid does initialisation in the kernel - md initialised the
 superblock in mdadm).

This means that for dm-raid we cannot currently trust the new ->nodes
field. So:
 - use __GFP_ZERO to initialise the superblock properly for all new
    arrays
 - initialise all fields in bitmap_info in bitmap_new_disk_sb
 - ignore ->nodes for dm arrays (yes, this is a hack)

This bug exposes dm-raid to bug in the (still experimental) md-cluster
code, so it is suitable for -stable.  It does cause crashes.

References: https://bugzilla.kernel.org/show_bug.cgi?id=100491


Cc: stable@vger.kernel.org (v4.1)
Signed-off-By: default avatarGoldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.com>
parent ee5d004f

drivers/md/bitmap.c

+12 −3
Original line number Diff line number Diff line
@@ -494,7 +494,7 @@ static int bitmap_new_disk_sb(struct bitmap *bitmap) 
	bitmap_super_t *sb;

	unsigned long chunksize, daemon_sleep, write_behind;



	bitmap->storage.sb_page = alloc_page(GFP_KERNEL);

	bitmap->storage.sb_page = alloc_page(GFP_KERNEL | __GFP_ZERO);

	if (bitmap->storage.sb_page == NULL)

		return -ENOMEM;

	bitmap->storage.sb_page->index = 0;
@@ -541,6 +541,7 @@ static int bitmap_new_disk_sb(struct bitmap *bitmap) 
	sb->state = cpu_to_le32(bitmap->flags);

	bitmap->events_cleared = bitmap->mddev->events;

	sb->events_cleared = cpu_to_le64(bitmap->mddev->events);

	bitmap->mddev->bitmap_info.nodes = 0;



	kunmap_atomic(sb);
@@ -611,8 +612,16 @@ static int bitmap_read_sb(struct bitmap *bitmap) 
	daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;

	write_behind = le32_to_cpu(sb->write_behind);

	sectors_reserved = le32_to_cpu(sb->sectors_reserved);

	/* XXX: This is a hack to ensure that we don't use clustering

	 *  in case:

	 *	- dm-raid is in use and

	 *	- the nodes written in bitmap_sb is erroneous.

	 */

	if (!bitmap->mddev->sync_super) {

		nodes = le32_to_cpu(sb->nodes);

	strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64);

		strlcpy(bitmap->mddev->bitmap_info.cluster_name,

				sb->cluster_name, 64);

	}



	/* verify that the bitmap-specific fields are valid */

	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))