dm thin: remove cells from stack
This patch takes advantage of the new bio-prison interface where the
memory is now passed in rather than using a mempool in bio-prison.
This allows the map function to avoid performing potentially-blocking
allocations that could lead to deadlocks: We want to avoid the cell
allocation that is done in bio_detain.
(The potential for mempool deadlocks still remains in other functions
that use bio_detain.)
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-bio-prison.h b/drivers/md/dm-bio-prison.h
index 11af2182..981a02d 100644
--- a/drivers/md/dm-bio-prison.h
+++ b/drivers/md/dm-bio-prison.h
@@ -22,7 +22,6 @@
* subsequently unlocked the bios become available.
*/
struct dm_bio_prison;
-struct dm_bio_prison_cell;
/* FIXME: this needs to be more abstract */
struct dm_cell_key {
@@ -31,6 +30,17 @@
dm_block_t block;
};
+/*
+ * Treat this as opaque, only in header so callers can manage allocation
+ * themselves.
+ */
+struct dm_bio_prison_cell {
+ struct hlist_node list;
+ struct dm_cell_key key;
+ struct bio *holder;
+ struct bio_list bios;
+};
+
struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
void dm_bio_prison_destroy(struct dm_bio_prison *prison);