On 2019/6/9 6:46 下午, Pierre JUHEN wrote:
> Hi Coly,
>
> As Rolf and I said, the value of preceding_key_p in the stack cannot be
> set to NULL by your code.
>
> The modified patch hereafter does what you expect (I think).
>
Oh, I understand now. Yes you are right, I made a mistake in previous
patch. I will post an update version which uses "struct bkey
**preceding_key_p" as parameter of preceding_key().
And I will add Reviewed-by: tag to you (Pierre and Rolf) in update
version. Thanks for your review!
Coly Li
>
>
> drivers/md/bcache/bset.c | 16 +++++++++++++---
> drivers/md/bcache/bset.h | 34 ++++++++++++++++++++--------------
> 2 files changed, 33 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
> index 8f07fa6e1739..9422f3f1c682 100644
> --- a/drivers/md/bcache/bset.c
> +++ b/drivers/md/bcache/bset.c
> @@ -887,12 +887,22 @@ unsigned int bch_btree_insert_key(struct
> btree_keys *b, struct bkey *k,
> struct bset *i = bset_tree_last(b)->data;
> struct bkey *m, *prev = NULL;
> struct btree_iter iter;
> + struct bkey preceding_key_on_stack = ZERO_KEY;
> + struct bkey *preceding_key_p = &preceding_key_on_stack;
>
> BUG_ON(b->ops->is_extents && !KEY_SIZE(k));
>
> - m = bch_btree_iter_init(b, &iter, b->ops->is_extents
> - ? PRECEDING_KEY(&START_KEY(k))
> - : PRECEDING_KEY(k));
> + /*
> + * If k has preceding key, preceding_key_p will be set to address
> + * of k's preceding key; otherwise preceding_key_p will be set
> + * to NULL inside preceding_key().
> + */
> + if (b->ops->is_extents)
> + preceding_key_p = preceding_key(&START_KEY(k), preceding_key_p);
> + else
> + preceding_key_p = preceding_key(k, preceding_key_p);
> +
> + m = bch_btree_iter_init(b, &iter, preceding_key_p);
>
> if (b->ops->insert_fixup(b, k, &iter, replace_key))
> return status;
> diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h
> index bac76aabca6d..6ab165dcb717 100644
> --- a/drivers/md/bcache/bset.h
> +++ b/drivers/md/bcache/bset.h
> @@ -434,20 +434,26 @@ static inline bool bch_cut_back(const struct bkey
> *where, struct bkey *k)
> return __bch_cut_back(where, k);
> }
>
> -#define PRECEDING_KEY(_k) \
> -({ \
> - struct bkey *_ret = NULL; \
> - \
> - if (KEY_INODE(_k) || KEY_OFFSET(_k)) { \
> - _ret = &KEY(KEY_INODE(_k), KEY_OFFSET(_k), 0); \
> - \
> - if (!_ret->low) \
> - _ret->high--; \
> - _ret->low--; \
> - } \
> - \
> - _ret; \
> -})
> +/*
> + * Pointer preceding_key_p points to a memory object to store preceding
> + * key of k. If the preceding key does not exist, set preceding_key_p to
> + * NULL. So the caller of preceding_key() needs to take care of memory
> + * which preceding_key_p pointed to before calling preceding_key().
> + * Currently the only caller of preceding_key() is bch_btree_insert_key(),
> + * and preceding_key_p points to an on-stack variable, so the memory
> + * release is handled by stackframe itself.
> + */
> +static inline struct bkey *preceding_key(struct bkey *k, struct bkey
> *preceding_key_p)
> +{
> + if (KEY_INODE(k) || KEY_OFFSET(k)) {
> + *preceding_key_p = KEY(KEY_INODE(k), KEY_OFFSET(k), 0);
> + if (!preceding_key_p->low)
> + preceding_key_p->high--;
> + preceding_key_p->low--;
> + return (preceding_key_p);
> + } else {
> + return(NULL);
> + }
> +}
>
> static inline bool bch_ptr_invalid(struct btree_keys *b, const struct
> bkey *k)
> {
>
>
--
Coly Li
