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Subject[PATCH 033 of 35] Simplify stacking of IO restrictions

Stacking device drives (dm/md) no longer need to worry about
most queue limits as they are handled at a lower level. The
only limit of any interest at the top level now is the hard
sector size.

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./block/ll_rw_blk.c | 14 ---------
./drivers/md/dm-table.c | 61 ----------------------------------------
./include/linux/device-mapper.h | 6 ---
3 files changed, 81 deletions(-)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
--- .prev/block/ll_rw_blk.c 2007-07-31 11:21:27.000000000 +1000
+++ ./block/ll_rw_blk.c 2007-07-31 11:21:28.000000000 +1000
@@ -690,11 +690,6 @@ void blk_queue_hardsect_size(struct requ

EXPORT_SYMBOL(blk_queue_hardsect_size);

-/*
- * Returns the minimum that is _not_ zero, unless both are zero.
- */
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
/**
* blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
* @t: the stacking driver (top)
@@ -702,16 +697,7 @@ EXPORT_SYMBOL(blk_queue_hardsect_size);
**/
void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
{
- /* zero is "infinity" */
- t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors);
- t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors);
-
- t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
- t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
- t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
- if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
- clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
}

EXPORT_SYMBOL(blk_queue_stack_limits);
diff .prev/drivers/md/dm-table.c ./drivers/md/dm-table.c
--- .prev/drivers/md/dm-table.c 2007-07-31 11:21:27.000000000 +1000
+++ ./drivers/md/dm-table.c 2007-07-31 11:21:28.000000000 +1000
@@ -75,34 +75,12 @@ static unsigned int int_log(unsigned int
}

/*
- * Returns the minimum that is _not_ zero, unless both are zero.
- */
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
-/*
* Combine two io_restrictions, always taking the lower value.
*/
static void combine_restrictions_low(struct io_restrictions *lhs,
struct io_restrictions *rhs)
{
- lhs->max_sectors =
- min_not_zero(lhs->max_sectors, rhs->max_sectors);
-
- lhs->max_phys_segments =
- min_not_zero(lhs->max_phys_segments, rhs->max_phys_segments);
-
- lhs->max_hw_segments =
- min_not_zero(lhs->max_hw_segments, rhs->max_hw_segments);
-
lhs->hardsect_size = max(lhs->hardsect_size, rhs->hardsect_size);
-
- lhs->max_segment_size =
- min_not_zero(lhs->max_segment_size, rhs->max_segment_size);
-
- lhs->seg_boundary_mask =
- min_not_zero(lhs->seg_boundary_mask, rhs->seg_boundary_mask);
-
- lhs->no_cluster |= rhs->no_cluster;
}

/*
@@ -536,26 +514,7 @@ void dm_set_device_limits(struct dm_targ
* into q this would just be a call to
* combine_restrictions_low()
*/
- rs->max_sectors =
- min_not_zero(rs->max_sectors, q->max_sectors);
-
- rs->max_phys_segments =
- min_not_zero(rs->max_phys_segments,
- q->max_phys_segments);
-
- rs->max_hw_segments =
- min_not_zero(rs->max_hw_segments, q->max_hw_segments);
-
rs->hardsect_size = max(rs->hardsect_size, q->hardsect_size);
-
- rs->max_segment_size =
- min_not_zero(rs->max_segment_size, q->max_segment_size);
-
- rs->seg_boundary_mask =
- min_not_zero(rs->seg_boundary_mask,
- q->seg_boundary_mask);
-
- rs->no_cluster |= !test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
}
EXPORT_SYMBOL_GPL(dm_set_device_limits);

@@ -684,18 +643,8 @@ int dm_split_args(int *argc, char ***arg

static void check_for_valid_limits(struct io_restrictions *rs)
{
- if (!rs->max_sectors)
- rs->max_sectors = SAFE_MAX_SECTORS;
- if (!rs->max_phys_segments)
- rs->max_phys_segments = MAX_PHYS_SEGMENTS;
- if (!rs->max_hw_segments)
- rs->max_hw_segments = MAX_HW_SEGMENTS;
if (!rs->hardsect_size)
rs->hardsect_size = 1 << SECTOR_SHIFT;
- if (!rs->max_segment_size)
- rs->max_segment_size = MAX_SEGMENT_SIZE;
- if (!rs->seg_boundary_mask)
- rs->seg_boundary_mask = -1;
}

int dm_table_add_target(struct dm_table *t, const char *type,
@@ -874,17 +823,7 @@ void dm_table_set_restrictions(struct dm
* Make sure we obey the optimistic sub devices
* restrictions.
*/
- blk_queue_max_sectors(q, t->limits.max_sectors);
- q->max_phys_segments = t->limits.max_phys_segments;
- 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->seg_boundary_mask = t->limits.seg_boundary_mask;
- if (t->limits.no_cluster)
- q->queue_flags &= ~(1 << QUEUE_FLAG_CLUSTER);
- else
- q->queue_flags |= (1 << QUEUE_FLAG_CLUSTER);
-
}

unsigned int dm_table_get_num_targets(struct dm_table *t)
diff .prev/include/linux/device-mapper.h ./include/linux/device-mapper.h
--- .prev/include/linux/device-mapper.h 2007-07-31 11:19:51.000000000 +1000
+++ ./include/linux/device-mapper.h 2007-07-31 11:21:28.000000000 +1000
@@ -110,13 +110,7 @@ struct target_type {
};

struct io_restrictions {
- unsigned int max_sectors;
- unsigned short max_phys_segments;
- unsigned short max_hw_segments;
unsigned short hardsect_size;
- unsigned int max_segment_size;
- unsigned long seg_boundary_mask;
- unsigned char no_cluster; /* inverted so that 0 is default */
};

struct dm_target {
-
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