lru_cache: consolidate lc_get and lc_try_get
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/lib/lru_cache.c b/lib/lru_cache.c
index 4f638b8..1762168 100644
--- a/lib/lru_cache.c
+++ b/lib/lru_cache.c
@@ -308,6 +308,58 @@
return 0;
}
+static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, bool may_change)
+{
+ struct lc_element *e;
+
+ PARANOIA_ENTRY();
+ if (lc->flags & LC_STARVING) {
+ ++lc->starving;
+ RETURN(NULL);
+ }
+
+ e = lc_find(lc, enr);
+ if (e) {
+ ++lc->hits;
+ if (e->refcnt++ == 0)
+ lc->used++;
+ list_move(&e->list, &lc->in_use); /* Not evictable... */
+ RETURN(e);
+ }
+
+ ++lc->misses;
+ if (!may_change)
+ RETURN(NULL);
+
+ /* In case there is nothing available and we can not kick out
+ * the LRU element, we have to wait ...
+ */
+ if (!lc_unused_element_available(lc)) {
+ __set_bit(__LC_STARVING, &lc->flags);
+ RETURN(NULL);
+ }
+
+ /* it was not present in the active set.
+ * we are going to recycle an unused (or even "free") element.
+ * user may need to commit a transaction to record that change.
+ * we serialize on flags & LC_DIRTY */
+ if (test_and_set_bit(__LC_DIRTY, &lc->flags)) {
+ ++lc->dirty;
+ RETURN(NULL);
+ }
+
+ e = lc_get_unused_element(lc);
+ BUG_ON(!e);
+
+ clear_bit(__LC_STARVING, &lc->flags);
+ BUG_ON(++e->refcnt != 1);
+ lc->used++;
+
+ lc->changing_element = e;
+ lc->new_number = enr;
+
+ RETURN(e);
+}
/**
* lc_get - get element by label, maybe change the active set
@@ -348,78 +400,28 @@
*/
struct lc_element *lc_get(struct lru_cache *lc, unsigned int enr)
{
- struct lc_element *e;
-
- PARANOIA_ENTRY();
- if (lc->flags & LC_STARVING) {
- ++lc->starving;
- RETURN(NULL);
- }
-
- e = lc_find(lc, enr);
- if (e) {
- ++lc->hits;
- if (e->refcnt++ == 0)
- lc->used++;
- list_move(&e->list, &lc->in_use); /* Not evictable... */
- RETURN(e);
- }
-
- ++lc->misses;
-
- /* In case there is nothing available and we can not kick out
- * the LRU element, we have to wait ...
- */
- if (!lc_unused_element_available(lc)) {
- __set_bit(__LC_STARVING, &lc->flags);
- RETURN(NULL);
- }
-
- /* it was not present in the active set.
- * we are going to recycle an unused (or even "free") element.
- * user may need to commit a transaction to record that change.
- * we serialize on flags & LC_DIRTY */
- if (test_and_set_bit(__LC_DIRTY, &lc->flags)) {
- ++lc->dirty;
- RETURN(NULL);
- }
-
- e = lc_get_unused_element(lc);
- BUG_ON(!e);
-
- clear_bit(__LC_STARVING, &lc->flags);
- BUG_ON(++e->refcnt != 1);
- lc->used++;
-
- lc->changing_element = e;
- lc->new_number = enr;
-
- RETURN(e);
+ return __lc_get(lc, enr, 1);
}
-/* similar to lc_get,
- * but only gets a new reference on an existing element.
- * you either get the requested element, or NULL.
- * will be consolidated into one function.
+/**
+ * lc_try_get - get element by label, if present; do not change the active set
+ * @lc: the lru cache to operate on
+ * @enr: the label to look up
+ *
+ * Finds an element in the cache, increases its usage count,
+ * "touches" and returns it.
+ *
+ * Return values:
+ * NULL
+ * The cache was marked %LC_STARVING,
+ * or the requested label was not in the active set
+ *
+ * pointer to the element with the REQUESTED element number.
+ * In this case, it can be used right away
*/
struct lc_element *lc_try_get(struct lru_cache *lc, unsigned int enr)
{
- struct lc_element *e;
-
- PARANOIA_ENTRY();
- if (lc->flags & LC_STARVING) {
- ++lc->starving;
- RETURN(NULL);
- }
-
- e = lc_find(lc, enr);
- if (e) {
- ++lc->hits;
- if (e->refcnt++ == 0)
- lc->used++;
- list_move(&e->list, &lc->in_use); /* Not evictable... */
- }
- RETURN(e);
+ return __lc_get(lc, enr, 0);
}
/**