Function bch_btree_keys_init() initializes b->set[].size and
b->set[].data to zero. As the code comments indicates, these code indeed
is unncessary, because both struct btree_keys and struct bset_tree are
nested embedded into struct btree, when struct btree is filled with 0
bits by kzalloc() in mca_bucket_alloc(), b->set[].size and
b->set[].data are initialized to 0 (a.k.a NULL) already.
This patch removes the redundant code, and add comments in
bch_btree_keys_init() and mca_bucket_alloc() to explain why it's safe.
Signed-off-by: Coly Li <colyli@xxxxxxx>
---
drivers/md/bcache/bset.c | 15 ++++++---------
drivers/md/bcache/btree.c | 4 ++++
2 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index e36a108d3648..8af9509e78bd 100644
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -347,22 +347,19 @@ EXPORT_SYMBOL(bch_btree_keys_alloc);
void bch_btree_keys_init(struct btree_keys *b, const struct btree_keys_ops *ops,
bool *expensive_debug_checks)
{
- unsigned int i;
-
b->ops = ops;
b->expensive_debug_checks = expensive_debug_checks;
b->nsets = 0;
b->last_set_unwritten = 0;
- /* XXX: shouldn't be needed */
- for (i = 0; i < MAX_BSETS; i++)
- b->set[i].size = 0;
/*
- * Second loop starts at 1 because b->keys[0]->data is the memory we
- * allocated
+ * struct btree_keys in embedded in struct btree, and struct
+ * bset_tree is embedded into struct btree_keys. They are all
+ * initialized as 0 by kzalloc() in mca_bucket_alloc(), and
+ * b->set[0].data is allocated in bch_btree_keys_alloc(), so we
+ * don't have to initiate b->set[].size and b->set[].data here
+ * any more.
*/
- for (i = 1; i < MAX_BSETS; i++)
- b->set[i].data = NULL;
}
EXPORT_SYMBOL(bch_btree_keys_init);
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 773f5fdad25f..cf38a1b031fa 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -613,6 +613,10 @@ static void mca_data_alloc(struct btree *b, struct bkey *k, gfp_t gfp)
static struct btree *mca_bucket_alloc(struct cache_set *c,
struct bkey *k, gfp_t gfp)
{
+ /*
+ * kzalloc() is necessary here for initialization,
+ * see code comments in bch_btree_keys_init().
+ */
struct btree *b = kzalloc(sizeof(struct btree), gfp);
if (!b)
--
2.16.4
