dm bio prison: introduce support for locking ranges of blocks
Ranges will be placed in the same cell if they overlap.
Range locking is a prerequisite for more efficient multi-block discard
support in both the cache and thin-provisioning targets.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-bio-prison.h b/drivers/md/dm-bio-prison.h
index b039886..74cf011 100644
--- a/drivers/md/dm-bio-prison.h
+++ b/drivers/md/dm-bio-prison.h
@@ -23,11 +23,14 @@
*/
struct dm_bio_prison;
-/* FIXME: this needs to be more abstract */
+/*
+ * Keys define a range of blocks within either a virtual or physical
+ * device.
+ */
struct dm_cell_key {
int virtual;
dm_thin_id dev;
- dm_block_t block;
+ dm_block_t block_begin, block_end;
};
/*
@@ -59,7 +62,7 @@
struct dm_bio_prison_cell *cell);
/*
- * Creates, or retrieves a cell for the given key.
+ * Creates, or retrieves a cell that overlaps the given key.
*
* Returns 1 if pre-existing cell returned, zero if new cell created using
* @cell_prealloc.
@@ -70,7 +73,8 @@
struct dm_bio_prison_cell **cell_result);
/*
- * An atomic op that combines retrieving a cell, and adding a bio to it.
+ * An atomic op that combines retrieving or creating a cell, and adding a
+ * bio to it.
*
* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
*/