Change mapped device to implement direct_access function,
dm_blk_direct_access(), which calls a target direct_access
function. 'struct target_type' is extended to have target
direct_access interface. This function limits direct
accessible size to the dm_target's limit with max_io_len().
Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Alasdair Kergon <agk@xxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
drivers/md/dm.c | 29 +++++++++++++++++++++++++++++
include/linux/device-mapper.h | 10 ++++++++++
2 files changed, 39 insertions(+)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 1b2f962..6e9f958 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1473,6 +1473,34 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
}
EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
+static long dm_blk_direct_access(struct block_device *bdev, sector_t sector,
+ void __pmem **kaddr, pfn_t *pfn, long size)
+{
+ struct mapped_device *md = bdev->bd_disk->private_data;
+ struct dm_table *map;
+ struct dm_target *ti;
+ int srcu_idx;
+ long len, ret = -EIO;
+
+ map = dm_get_live_table(md, &srcu_idx);
+ if (!map)
+ return ret;
+
+ ti = dm_table_find_target(map, sector);
+ if (!dm_target_is_valid(ti))
+ goto out;
+
+ len = max_io_len(sector, ti) << SECTOR_SHIFT;
+ size = min(len, size);
+
+ if (ti->type->direct_access)
+ ret = ti->type->direct_access(ti, sector, kaddr, pfn, size);
+
+out:
+ dm_put_live_table(md, srcu_idx);
+ return min(ret, size);
+}
+
/*
* A target may call dm_accept_partial_bio only from the map routine. It is
* allowed for all bio types except REQ_FLUSH.
@@ -3721,6 +3749,7 @@ static const struct block_device_operations dm_blk_dops = {
.open = dm_blk_open,
.release = dm_blk_close,
.ioctl = dm_blk_ioctl,
+ .direct_access = dm_blk_direct_access,
.getgeo = dm_blk_getgeo,
.pr_ops = &dm_pr_ops,
.owner = THIS_MODULE
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 0830c9e..16e6c8c 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -116,6 +116,15 @@ typedef void (*dm_io_hints_fn) (struct dm_target *ti,
*/
typedef int (*dm_busy_fn) (struct dm_target *ti);
+/*
+ * Returns:
+ * < 0 : error
+ * >= 0 : the number of bytes accessible at the address
+ */
+typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector,
+ void __pmem **kaddr, pfn_t *pfn,
+ long size);
+
void dm_error(const char *message);
struct dm_dev {
@@ -162,6 +171,7 @@ struct target_type {
dm_busy_fn busy;
dm_iterate_devices_fn iterate_devices;
dm_io_hints_fn io_hints;
+ dm_direct_access_fn direct_access;
/* For internal device-mapper use. */
struct list_head list;
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
