bcache: Explicitly track btree node's parent
This is prep work for the reworked btree insertion code.
The way we set b->parent is ugly and hacky... the problem is, when
btree_split() or garbage collection splits or rewrites a btree node, the
parent changes for all its (potentially already cached) children.
I may change this later and add some code to look through the btree node
cache and find all our cached child nodes and change the parent pointer
then...
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index 8a1c7e6..6d2fb75 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -125,6 +125,7 @@
unsigned long seq;
struct rw_semaphore lock;
struct cache_set *c;
+ struct btree *parent;
unsigned long flags;
uint16_t written; /* would be nice to kill */
@@ -327,12 +328,13 @@
({ \
int _r, l = (b)->level - 1; \
bool _w = l <= (op)->lock; \
- struct btree *_b = bch_btree_node_get((b)->c, key, l, op); \
- if (!IS_ERR(_b)) { \
- _r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__); \
- rw_unlock(_w, _b); \
+ struct btree *_child = bch_btree_node_get((b)->c, key, l, op); \
+ if (!IS_ERR(_child)) { \
+ _child->parent = (b); \
+ _r = bch_btree_ ## fn(_child, op, ##__VA_ARGS__); \
+ rw_unlock(_w, _child); \
} else \
- _r = PTR_ERR(_b); \
+ _r = PTR_ERR(_child); \
_r; \
})
@@ -350,8 +352,10 @@
bool _w = insert_lock(op, _b); \
rw_lock(_w, _b, _b->level); \
if (_b == (c)->root && \
- _w == insert_lock(op, _b)) \
+ _w == insert_lock(op, _b)) { \
+ _b->parent = NULL; \
_r = bch_btree_ ## fn(_b, op, ##__VA_ARGS__); \
+ } \
rw_unlock(_w, _b); \
bch_cannibalize_unlock(c, &(op)->cl); \
} while (_r == -EINTR); \