The patch 6b5e718cc138 ("dm bufio: relax alignment constraint on slab
cache") relaxed alignment on dm-bufio cache, however it may break dm-crypt
or dm-integrity.dm-crypt and dm-integrity require that the size of bio vector entries (bv_len) is aligned on its sector size. bv_offset doesn't have to be aligned, but bv_len must be. XFS sends unaligned bios, but they do not cross page boundary, so the requirement for aligned bv_len is met. The patch 6b5e718cc138 made dm-bufio send unaligned bios that cross page boundary, this could break dm-crypt and dm-integrity. This patch reinstates the alignment. Note that misaligned entries only happen when we use slab/slub debugging. Without debugging, the entries are always aligned. Signed-off-by: Mikulas Patocka <[email protected]> Fixes: 6b5e718cc138 ("dm bufio: relax alignment constraint on slab cache") --- drivers/md/dm-bufio.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) Index: linux-2.6/drivers/md/dm-bufio.c =================================================================== --- linux-2.6.orig/drivers/md/dm-bufio.c 2018-04-17 19:59:49.000000000 +0200 +++ linux-2.6/drivers/md/dm-bufio.c 2018-04-19 14:31:10.000000000 +0200 @@ -1681,8 +1681,9 @@ struct dm_bufio_client *dm_bufio_client_ if (block_size <= KMALLOC_MAX_SIZE && (block_size < PAGE_SIZE || !is_power_of_2(block_size))) { - snprintf(slab_name, sizeof slab_name, "dm_bufio_cache-%u", c->block_size); - c->slab_cache = kmem_cache_create(slab_name, c->block_size, ARCH_KMALLOC_MINALIGN, + unsigned align = min(1U << __ffs(block_size), (unsigned)PAGE_SIZE); + snprintf(slab_name, sizeof slab_name, "dm_bufio_cache-%u", block_size); + c->slab_cache = kmem_cache_create(slab_name, block_size, align, SLAB_RECLAIM_ACCOUNT, NULL); if (!c->slab_cache) { r = -ENOMEM; -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
