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bcache: remove unncessary code in bch_btree_keys_init()

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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@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Coly Li 2019-06-28 19:59:34 +08:00 committed by Jens Axboe
parent 0b13efecf5
commit bd9026c8a7
2 changed files with 10 additions and 9 deletions
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15
drivers/md/bcache/bset.c
View File

@ -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);

4
drivers/md/bcache/btree.c
View File

@ -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)