[RFC v2 PATCH 04/10] dm: add methods to set and get reserved space

Brian Foster
2016-04-12T16:42:57Z

From: Mike Snitzer <snitzer@redhat.com>

[BF: Condensed to single function.]

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
drivers/md/dm.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/device-mapper.h | 5 +++++
2 files changed, 46 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index be49057..8f95e78 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -664,6 +664,46 @@ out:
return r;
}

+/*
+ * FIXME: factor out common helper that can be used by
+ * multiple block_device_operations -> target methods
+ * (including dm_blk_ioctl above)
+ */
+
+static int dm_blk_reserve_space(struct block_device *bdev, int mode,
+ sector_t offset, sector_t len, sector_t *res)
+{
+ 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->reserve_space)
+ goto out;
+
+ if (dm_suspended_md(md)) {
+ r = -EAGAIN;
+ goto out;
+ }
+
+ r = tgt->type->reserve_space(tgt, mode, offset, len, res);
+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);
@@ -3723,6 +3763,7 @@ static const struct block_device_operations dm_blk_dops = {
.ioctl = dm_blk_ioctl,
.getgeo = dm_blk_getgeo,
.pr_ops = &dm_pr_ops,
+ .reserve_space = dm_blk_reserve_space,
.owner = THIS_MODULE
};

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 0830c9e..b4825db 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -116,6 +116,10 @@ typedef void (*dm_io_hints_fn) (struct dm_target *ti,
*/
typedef int (*dm_busy_fn) (struct dm_target *ti);

+typedef int (*dm_reserve_space_fn) (struct dm_target *ti, int mode,
+ sector_t offset, sector_t len,
+ sector_t *res);
+
void dm_error(const char *message);

struct dm_dev {
@@ -162,6 +166,7 @@ struct target_type {
dm_busy_fn busy;
dm_iterate_devices_fn iterate_devices;
dm_io_hints_fn io_hints;
+ dm_reserve_space_fn reserve_space;

/* For internal device-mapper use. */
struct list_head list;
--
2.4.11