[RFC PATCH 6/9] dm: add method to provision space

[Brian Foster <bfoster@xxxxxxxxxx>]

Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
 drivers/md/dm.c               | 35 +++++++++++++++++++++++++++++++++++
 include/linux/device-mapper.h |  2 ++
 2 files changed, 37 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 4da5d3e..e1aec28 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -737,6 +737,40 @@ out:
        return r;
 }
 
+static int dm_blk_provision_space(struct block_device *bdev,
+                                 sector_t offset, sector_t len)
+{
+       struct mapped_device *md = bdev->bd_disk->private_data;
+       int srcu_idx;
+       struct dm_table *map;
+       struct dm_target *tgt;
+       int r = -EINVAL;
+
+       map = dm_get_live_table(md, &srcu_idx);
+
+       if (!map || !dm_table_get_size(map))
+               goto out;
+
+       /* We only support devices that have a single target */
+       if (dm_table_get_num_targets(map) != 1)
+               goto out;
+
+       tgt = dm_table_get_target(map, 0);
+       if (!tgt->type->provision_space)
+               goto out;
+
+       if (dm_suspended_md(md)) {
+               r = -EAGAIN;
+               goto out;
+       }
+
+       r = tgt->type->provision_space(tgt, offset, len);
+out:
+       dm_put_live_table(md, srcu_idx);
+
+       return r;
+}
+
 static struct dm_io *alloc_io(struct mapped_device *md)
 {
        return mempool_alloc(md->io_pool, GFP_NOIO);
@@ -3798,6 +3832,7 @@ static const struct block_device_operations dm_blk_dops = 
{
        .pr_ops = &dm_pr_ops,
        .reserve_space = dm_blk_reserve_space,
        .get_reserved_space = dm_blk_get_reserved_space,
+       .provision_space = dm_blk_provision_space,
        .owner = THIS_MODULE
 };
 
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 540c772..0ebf172 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -118,6 +118,7 @@ typedef int (*dm_busy_fn) (struct dm_target *ti);
 
 typedef int (*dm_reserve_space_fn) (struct dm_target *ti, sector_t nr_sects);
 typedef int (*dm_get_reserved_space_fn) (struct dm_target *ti, sector_t 
*nr_sects);
+typedef int (*dm_provision_space_fn) (struct dm_target *ti, sector_t offset, 
sector_t len);
 
 void dm_error(const char *message);
 
@@ -167,6 +168,7 @@ struct target_type {
        dm_io_hints_fn io_hints;
        dm_reserve_space_fn reserve_space;
        dm_get_reserved_space_fn get_reserved_space;
+       dm_provision_space_fn provision_space;
 
        /* For internal device-mapper use. */
        struct list_head list;
-- 
2.4.3