DM: Fix device mapper topology stacking

Make DM use bdev_stack_limits() function so that partition offsets get
taken into account when calculating alignment.  Clarify stacking
warnings.

Also remove obsolete clearing of final alignment_offset and misalignment
flag.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair G. Kergon <agk@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 5 insertions, 15 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index be625475cf6d..4b22feb01a0c 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -503,16 +503,15 @@ int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
                 return 0;
         }
 
-        if (blk_stack_limits(limits, &q->limits, start << 9) < 0)
-                DMWARN("%s: target device %s is misaligned: "
+        if (bdev_stack_limits(limits, bdev, start) < 0)
+                DMWARN("%s: adding target device %s caused an alignment inconsistency: "
                        "physical_block_size=%u, logical_block_size=%u, "
                        "alignment_offset=%u, start=%llu",
                        dm_device_name(ti->table->md), bdevname(bdev, b),
                        q->limits.physical_block_size,
                        q->limits.logical_block_size,
                        q->limits.alignment_offset,
-                       (unsigned long long) start << 9);
-
+                       (unsigned long long) start << SECTOR_SHIFT);
 
         /*
          * Check if merge fn is supported.
@@ -1026,9 +1025,9 @@ combine_limits:
                  * for the table.
                  */
                 if (blk_stack_limits(limits, &ti_limits, 0) < 0)
-                        DMWARN("%s: target device "
+                        DMWARN("%s: adding target device "
                                "(start sect %llu len %llu) "
-                               "is misaligned",
+                               "caused an alignment inconsistency",
                                dm_device_name(table->md),
                                (unsigned long long) ti->begin,
                                (unsigned long long) ti->len);
@@ -1080,15 +1079,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
                                struct queue_limits *limits)
 {
         /*
-         * Each target device in the table has a data area that should normally
-         * be aligned such that the DM device's alignment_offset is 0.
-         * FIXME: Propagate alignment_offsets up the stack and warn of
-         *        sub-optimal or inconsistent settings.
-         */
-        limits->alignment_offset = 0;
-        limits->misaligned = 0;
-
-        /*
          * Copy table's limits to the DM device's request_queue
          */
         q->limits = *limits;