From d3b178adb3a3adf54ecf77758138b654c3ee7f09 Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Wed, 22 Jul 2015 12:09:17 -0500 Subject: [PATCH] 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: Goldwyn Rodrigues Signed-off-by: NeilBrown --- drivers/md/bitmap.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index 135a0907e9de..c90118e90708 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -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 @@ re_read: 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); - nodes = le32_to_cpu(sb->nodes); - strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64); + /* 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); + } /* verify that the bitmap-specific fields are valid */ if (sb->magic != cpu_to_le32(BITMAP_MAGIC)) -- 2.39.5