lru_cache: introduce lc_get_cumulative() (cbe5e610) · Commits · 戴 / test

include/linux/lru_cache.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -256,6 +256,7 @@ extern void lc_destroy(struct lru_cache *lc);
		extern void lc_set(struct lru_cache *lc, unsigned int enr, int index);
		extern void lc_del(struct lru_cache lc, struct lc_element element);

		extern struct lc_element lc_get_cumulative(struct lru_cache lc, unsigned int enr);
		extern struct lc_element lc_try_get(struct lru_cache lc, unsigned int enr);
		extern struct lc_element lc_find(struct lru_cache lc, unsigned int enr);
		extern struct lc_element lc_get(struct lru_cache lc, unsigned int enr);

lib/lru_cache.c

+46 −10

Original line number	Diff line number	Diff line
		@@ -365,7 +365,13 @@ static int lc_unused_element_available(struct lru_cache *lc)
		return 0;
		}

		static struct lc_element __lc_get(struct lru_cache lc, unsigned int enr, bool may_change)
		/* used as internal flags to __lc_get */
		enum {
		LC_GET_MAY_CHANGE = 1,
		LC_GET_MAY_USE_UNCOMMITTED = 2,
		};

		static struct lc_element __lc_get(struct lru_cache lc, unsigned int enr, unsigned int flags)
		{
		struct lc_element *e;

		@@ -380,22 +386,31 @@ static struct lc_element __lc_get(struct lru_cache lc, unsigned int enr, bool
		* this enr is currently being pulled in already,
		* and will be available once the pending transaction
		* has been committed. */
		if (e && e->lc_new_number == e->lc_number) {
		if (e) {
		if (e->lc_new_number != e->lc_number) {
		/* It has been found above, but on the "to_be_changed"
		* list, not yet committed. Don't pull it in twice,
		* wait for the transaction, then try again...
		*/
		if (!(flags & LC_GET_MAY_USE_UNCOMMITTED))
		RETURN(NULL);
		/* ... unless the caller is aware of the implications,
		* probably preparing a cumulative transaction. */
		++e->refcnt;
		++lc->hits;
		RETURN(e);
		}
		/* else: lc_new_number == lc_number; a real hit. */
		++lc->hits;
		if (e->refcnt++ == 0)
		lc->used++;
		list_move(&e->list, &lc->in_use); /* Not evictable... */
		RETURN(e);
		}
		/* e == NULL */

		++lc->misses;
		if (!may_change)
		RETURN(NULL);

		/* It has been found above, but on the "to_be_changed" list, not yet
		* committed. Don't pull it in twice, wait for the transaction, then
		* try again */
		if (e)
		if (!(flags & LC_GET_MAY_CHANGE))
		RETURN(NULL);

		/* To avoid races with lc_try_lock(), first, mark us dirty
		@@ -477,7 +492,27 @@ static struct lc_element __lc_get(struct lru_cache lc, unsigned int enr, bool
		*/
		struct lc_element lc_get(struct lru_cache lc, unsigned int enr)
		{
		return __lc_get(lc, enr, 1);
		return __lc_get(lc, enr, LC_GET_MAY_CHANGE);
		}

		/**
		* lc_get_cumulative - like lc_get; also finds to-be-changed elements
		* @lc: the lru cache to operate on
		* @enr: the label to look up
		*
		* Unlike lc_get this also returns the element for @enr, if it is belonging to
		* a pending transaction, so the return values are like for lc_get(),
		* plus:
		*
		* pointer to an element already on the "to_be_changed" list.
		* In this case, the cache was already marked %LC_DIRTY.
		*
		* Caller needs to make sure that the pending transaction is completed,
		* before proceeding to actually use this element.
		*/
		struct lc_element lc_get_cumulative(struct lru_cache lc, unsigned int enr)
		{
		return __lc_get(lc, enr, LC_GET_MAY_CHANGE\|LC_GET_MAY_USE_UNCOMMITTED);
		}

		/**
		@@ -648,3 +683,4 @@ EXPORT_SYMBOL(lc_seq_printf_stats);
		EXPORT_SYMBOL(lc_seq_dump_details);
		EXPORT_SYMBOL(lc_try_lock);
		EXPORT_SYMBOL(lc_is_used);
		EXPORT_SYMBOL(lc_get_cumulative);

Admin message