Commit bd9026c8 authored by Coly Li's avatar Coly Li Committed by Jens Axboe
Browse files

bcache: remove unncessary code in bch_btree_keys_init() 



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: default avatarColy Li <colyli@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0b13efec

drivers/md/bcache/bset.c

+6 −9
Original line number Diff line number Diff line
@@ -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);

drivers/md/bcache/btree.c

+4 −0
Original line number Diff line number Diff line
@@ -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)

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