dm: merge max_hw_sector

Make sure dm honours max_hw_sectors of underlying devices

  We still have no firm testing evidence in support of this patch but
  believe it may help to resolve some bug reports.  - agk

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index f3f952e347ed99cb6dad3aeddccffd5245ba4985..47818d8249cbf16f125328d39d2be54c0241130a 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -99,6 +99,9 @@ static void combine_restrictions_low(struct io_restrictions *lhs,
        lhs->max_segment_size =
                min_not_zero(lhs->max_segment_size, rhs->max_segment_size);
 
+       lhs->max_hw_sectors =
+               min_not_zero(lhs->max_hw_sectors, rhs->max_hw_sectors);
+
        lhs->seg_boundary_mask =
                min_not_zero(lhs->seg_boundary_mask, rhs->seg_boundary_mask);
 
@@ -566,6 +569,9 @@ void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev)
        rs->max_segment_size =
                min_not_zero(rs->max_segment_size, q->max_segment_size);
 
+       rs->max_hw_sectors =
+               min_not_zero(rs->max_hw_sectors, q->max_hw_sectors);
+
        rs->seg_boundary_mask =
                min_not_zero(rs->seg_boundary_mask,
                             q->seg_boundary_mask);
@@ -703,6 +709,8 @@ static void check_for_valid_limits(struct io_restrictions *rs)
 {
        if (!rs->max_sectors)
                rs->max_sectors = SAFE_MAX_SECTORS;
+       if (!rs->max_hw_sectors)
+               rs->max_hw_sectors = SAFE_MAX_SECTORS;
        if (!rs->max_phys_segments)
                rs->max_phys_segments = MAX_PHYS_SEGMENTS;
        if (!rs->max_hw_segments)
@@ -901,6 +909,7 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q)
        q->max_hw_segments = t->limits.max_hw_segments;
        q->hardsect_size = t->limits.hardsect_size;
        q->max_segment_size = t->limits.max_segment_size;
+       q->max_hw_sectors = t->limits.max_hw_sectors;
        q->seg_boundary_mask = t->limits.seg_boundary_mask;
        q->bounce_pfn = t->limits.bounce_pfn;
        if (t->limits.no_cluster)

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index b8b7c51389fe0ecff2608f63b928140601347a3f..e765e191663dde89ecc150639d2d4eee1096ae88 100644 (file)
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -115,6 +115,7 @@ struct io_restrictions {
        unsigned short          max_hw_segments;
        unsigned short          hardsect_size;
        unsigned int            max_segment_size;
+       unsigned int            max_hw_sectors;
        unsigned long           seg_boundary_mask;
        unsigned long           bounce_pfn;
        unsigned char           no_cluster; /* inverted so that 0 is default */