if (!entry)
return NULL;
entry->refcount = 1;
+ RB_CLEAR_NODE(&entry->rbnode);
return entry;
}
kmem_cache_free(zswap_entry_cache, entry);
}
-/* caller must hold the tree lock */
-static void zswap_entry_get(struct zswap_entry *entry)
-{
- entry->refcount++;
-}
-
-/* caller must hold the tree lock */
-static int zswap_entry_put(struct zswap_entry *entry)
-{
- entry->refcount--;
- return entry->refcount;
-}
-
/*********************************
* rbtree functions
**********************************/
return 0;
}
+static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
+{
+ if (!RB_EMPTY_NODE(&entry->rbnode)) {
+ rb_erase(&entry->rbnode, root);
+ RB_CLEAR_NODE(&entry->rbnode);
+ }
+}
+
+/*
+ * Carries out the common pattern of freeing and entry's zsmalloc allocation,
+ * freeing the entry itself, and decrementing the number of stored pages.
+ */
+static void zswap_free_entry(struct zswap_tree *tree,
+ struct zswap_entry *entry)
+{
+ zbud_free(tree->pool, entry->handle);
+ zswap_entry_cache_free(entry);
+ atomic_dec(&zswap_stored_pages);
+ zswap_pool_pages = zbud_get_pool_size(tree->pool);
+}
+
+/* caller must hold the tree lock */
+static void zswap_entry_get(struct zswap_entry *entry)
+{
+ entry->refcount++;
+}
+
+/* caller must hold the tree lock
+* remove from the tree and free it, if nobody reference the entry
+*/
+static void zswap_entry_put(struct zswap_tree *tree,
+ struct zswap_entry *entry)
+{
+ int refcount = --entry->refcount;
+
+ BUG_ON(refcount < 0);
+ if (refcount == 0) {
+ zswap_rb_erase(&tree->rbroot, entry);
+ zswap_free_entry(tree, entry);
+ }
+}
+
+/* caller must hold the tree lock */
+static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
+ pgoff_t offset)
+{
+ struct zswap_entry *entry = NULL;
+
+ entry = zswap_rb_search(root, offset);
+ if (entry)
+ zswap_entry_get(entry);
+
+ return entry;
+}
+
/*********************************
* per-cpu code
**********************************/
zswap_pool_pages);
}
-/*
- * Carries out the common pattern of freeing and entry's zsmalloc allocation,
- * freeing the entry itself, and decrementing the number of stored pages.
- */
-static void zswap_free_entry(struct zswap_tree *tree, struct zswap_entry *entry)
-{
- zbud_free(tree->pool, entry->handle);
- zswap_entry_cache_free(entry);
- atomic_dec(&zswap_stored_pages);
- zswap_pool_pages = zbud_get_pool_size(tree->pool);
-}
-
/*********************************
* writeback code
**********************************/
enum zswap_get_swap_ret {
ZSWAP_SWAPCACHE_NEW,
ZSWAP_SWAPCACHE_EXIST,
- ZSWAP_SWAPCACHE_NOMEM
+ ZSWAP_SWAPCACHE_FAIL,
};
/*
* added to the swap cache, and returned in retpage.
*
* If success, the swap cache page is returned in retpage
- * Returns 0 if page was already in the swap cache, page is not locked
- * Returns 1 if the new page needs to be populated, page is locked
- * Returns <0 on error
+ * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
+ * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
+ * the new page is added to swapcache and locked
+ * Returns ZSWAP_SWAPCACHE_FAIL on error
*/
static int zswap_get_swap_cache_page(swp_entry_t entry,
struct page **retpage)
if (new_page)
page_cache_release(new_page);
if (!found_page)
- return ZSWAP_SWAPCACHE_NOMEM;
+ return ZSWAP_SWAPCACHE_FAIL;
*retpage = found_page;
return ZSWAP_SWAPCACHE_EXIST;
}
struct page *page;
u8 *src, *dst;
unsigned int dlen;
- int ret, refcount;
+ int ret;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
/* find and ref zswap entry */
spin_lock(&tree->lock);
- entry = zswap_rb_search(&tree->rbroot, offset);
+ entry = zswap_entry_find_get(&tree->rbroot, offset);
if (!entry) {
/* entry was invalidated */
spin_unlock(&tree->lock);
return 0;
}
- zswap_entry_get(entry);
spin_unlock(&tree->lock);
BUG_ON(offset != entry->offset);
/* try to allocate swap cache page */
switch (zswap_get_swap_cache_page(swpentry, &page)) {
- case ZSWAP_SWAPCACHE_NOMEM: /* no memory */
+ case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
ret = -ENOMEM;
goto fail;
- case ZSWAP_SWAPCACHE_EXIST: /* page is unlocked */
+ case ZSWAP_SWAPCACHE_EXIST:
/* page is already in the swap cache, ignore for now */
page_cache_release(page);
ret = -EEXIST;
SetPageUptodate(page);
}
+ /* move it to the tail of the inactive list after end_writeback */
+ SetPageReclaim(page);
+
/* start writeback */
__swap_writepage(page, &wbc, end_swap_bio_write);
page_cache_release(page);
zswap_written_back_pages++;
spin_lock(&tree->lock);
-
/* drop local reference */
- zswap_entry_put(entry);
- /* drop the initial reference from entry creation */
- refcount = zswap_entry_put(entry);
+ zswap_entry_put(tree, entry);
/*
- * There are three possible values for refcount here:
- * (1) refcount is 1, load is in progress, unlink from rbtree,
- * load will free
- * (2) refcount is 0, (normal case) entry is valid,
- * remove from rbtree and free entry
- * (3) refcount is -1, invalidate happened during writeback,
- * free entry
- */
- if (refcount >= 0) {
- /* no invalidate yet, remove from rbtree */
- rb_erase(&entry->rbnode, &tree->rbroot);
- }
+ * There are two possible situations for entry here:
+ * (1) refcount is 1(normal case), entry is valid and on the tree
+ * (2) refcount is 0, entry is freed and not on the tree
+ * because invalidate happened during writeback
+ * search the tree and free the entry if find entry
+ */
+ if (entry == zswap_rb_search(&tree->rbroot, offset))
+ zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
- if (refcount <= 0) {
- /* free the entry */
- zswap_free_entry(tree, entry);
- return 0;
- }
- return -EAGAIN;
+ goto end;
+
+ /*
+ * if we get here due to ZSWAP_SWAPCACHE_EXIST
+ * a load may happening concurrently
+ * it is safe and okay to not free the entry
+ * if we free the entry in the following put
+ * it it either okay to return !0
+ */
fail:
spin_lock(&tree->lock);
- zswap_entry_put(entry);
+ zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
+
+end:
return ret;
}
if (ret == -EEXIST) {
zswap_duplicate_entry++;
/* remove from rbtree */
- rb_erase(&dupentry->rbnode, &tree->rbroot);
- if (!zswap_entry_put(dupentry)) {
- /* free */
- zswap_free_entry(tree, dupentry);
- }
+ zswap_rb_erase(&tree->rbroot, dupentry);
+ zswap_entry_put(tree, dupentry);
}
} while (ret == -EEXIST);
spin_unlock(&tree->lock);
struct zswap_entry *entry;
u8 *src, *dst;
unsigned int dlen;
- int refcount, ret;
+ int ret;
/* find */
spin_lock(&tree->lock);
- entry = zswap_rb_search(&tree->rbroot, offset);
+ entry = zswap_entry_find_get(&tree->rbroot, offset);
if (!entry) {
/* entry was written back */
spin_unlock(&tree->lock);
return -1;
}
- zswap_entry_get(entry);
spin_unlock(&tree->lock);
/* decompress */
BUG_ON(ret);
spin_lock(&tree->lock);
- refcount = zswap_entry_put(entry);
- if (likely(refcount)) {
- spin_unlock(&tree->lock);
- return 0;
- }
+ zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
- /*
- * We don't have to unlink from the rbtree because
- * zswap_writeback_entry() or zswap_frontswap_invalidate page()
- * has already done this for us if we are the last reference.
- */
- /* free */
-
- zswap_free_entry(tree, entry);
-
return 0;
}
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry;
- int refcount;
/* find */
spin_lock(&tree->lock);
}
/* remove from rbtree */
- rb_erase(&entry->rbnode, &tree->rbroot);
+ zswap_rb_erase(&tree->rbroot, entry);
/* drop the initial reference from entry creation */
- refcount = zswap_entry_put(entry);
+ zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
-
- if (refcount) {
- /* writeback in progress, writeback will free */
- return;
- }
-
- /* free */
- zswap_free_entry(tree, entry);
}
/* frees all zswap entries for the given swap type */
/* walk the tree and free everything */
spin_lock(&tree->lock);
- rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode) {
- zbud_free(tree->pool, entry->handle);
- zswap_entry_cache_free(entry);
- atomic_dec(&zswap_stored_pages);
- }
+ rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
+ zswap_free_entry(tree, entry);
tree->rbroot = RB_ROOT;
spin_unlock(&tree->lock);
git.openpandora.org / pandora-kernel.git / blobdiff