dm integrity: allow unaligned bv_offset

When slub_debug is enabled kmalloc returns unaligned memory. XFS uses
this unaligned memory for its buffers (if an unaligned buffer crosses a
page, XFS frees it and allocates a full page instead - see the function
xfs_buf_allocate_memory).

dm-integrity checks if bv_offset is aligned on page size and this check
fail with slub_debug and XFS.

Fix this bug by removing the bv_offset check, leaving only the check for
bv_len.

Fixes: 7eada909bfd7 ("dm: add integrity target")
Cc: stable@vger.kernel.org # v4.12+
Reported-by: Bruno Prémont <bonbons@sysophe.eu>
Reviewed-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 096fe9b66c50749cb841bcbafc4bc6cb6ca63be7..5e6737a44468d6bdcf29435c0f33149611dacb2a 100644 (file)
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1376,7 +1376,7 @@ static int dm_integrity_map(struct dm_target *ti, struct bio *bio)
                struct bvec_iter iter;
                struct bio_vec bv;
                bio_for_each_segment(bv, bio, iter) {
-                       if (unlikely((bv.bv_offset | bv.bv_len) & ((ic->sectors_per_block << SECTOR_SHIFT) - 1))) {
+                       if (unlikely(bv.bv_len & ((ic->sectors_per_block << SECTOR_SHIFT) - 1))) {
                                DMERR("Bio vector (%u,%u) is not aligned on %u-sector boundary",
                                        bv.bv_offset, bv.bv_len, ic->sectors_per_block);
                                return DM_MAPIO_KILL;