diff options
| -rw-r--r-- | mm/zswap.c | 63 |
1 files changed, 11 insertions, 52 deletions
diff --git a/mm/zswap.c b/mm/zswap.c index 7a69142817cb..96664cdee207 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -193,12 +193,6 @@ struct zswap_pool { * * rbnode - links the entry into red-black tree for the appropriate swap type * swpentry - associated swap entry, the offset indexes into the red-black tree - * refcount - the number of outstanding reference to the entry. This is needed - * to protect against premature freeing of the entry by code - * concurrent calls to load, invalidate, and writeback. The lock - * for the zswap_tree structure that contains the entry must - * be held while changing the refcount. Since the lock must - * be held, there is no reason to also make refcount atomic. * length - the length in bytes of the compressed page data. Needed during * decompression. For a same value filled page length is 0, and both * pool and lru are invalid and must be ignored. @@ -211,7 +205,6 @@ struct zswap_pool { struct zswap_entry { struct rb_node rbnode; swp_entry_t swpentry; - int refcount; unsigned int length; struct zswap_pool *pool; union { @@ -222,11 +215,6 @@ struct zswap_entry { struct list_head lru; }; -/* - * The tree lock in the zswap_tree struct protects a few things: - * - the rbtree - * - the refcount field of each entry in the tree - */ struct zswap_tree { struct rb_root rbroot; spinlock_t lock; @@ -890,14 +878,10 @@ static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry, return 0; } -static bool zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry) +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); - return true; - } - return false; + rb_erase(&entry->rbnode, root); + RB_CLEAR_NODE(&entry->rbnode); } /********************************* @@ -911,7 +895,6 @@ static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp, int nid) entry = kmem_cache_alloc_node(zswap_entry_cache, gfp, nid); if (!entry) return NULL; - entry->refcount = 1; RB_CLEAR_NODE(&entry->rbnode); return entry; } @@ -954,33 +937,15 @@ static void zswap_entry_free(struct zswap_entry *entry) zswap_update_total_size(); } -/* caller must hold the tree lock */ -static void zswap_entry_get(struct zswap_entry *entry) -{ - WARN_ON_ONCE(!entry->refcount); - entry->refcount++; -} - -/* caller must hold the tree lock */ -static void zswap_entry_put(struct zswap_entry *entry) -{ - WARN_ON_ONCE(!entry->refcount); - if (--entry->refcount == 0) { - WARN_ON_ONCE(!RB_EMPTY_NODE(&entry->rbnode)); - zswap_entry_free(entry); - } -} - /* - * If the entry is still valid in the tree, drop the initial ref and remove it - * from the tree. This function must be called with an additional ref held, - * otherwise it may race with another invalidation freeing the entry. + * The caller hold the tree lock and search the entry from the tree, + * so it must be on the tree, remove it from the tree and free it. */ static void zswap_invalidate_entry(struct zswap_tree *tree, struct zswap_entry *entry) { - if (zswap_rb_erase(&tree->rbroot, entry)) - zswap_entry_put(entry); + zswap_rb_erase(&tree->rbroot, entry); + zswap_entry_free(entry); } /********************************* @@ -1219,7 +1184,7 @@ static int zswap_writeback_entry(struct zswap_entry *entry, } /* Safe to deref entry after the entry is verified above. */ - zswap_entry_get(entry); + zswap_rb_erase(&tree->rbroot, entry); spin_unlock(&tree->lock); zswap_decompress(entry, &folio->page); @@ -1228,10 +1193,7 @@ static int zswap_writeback_entry(struct zswap_entry *entry, if (entry->objcg) count_objcg_event(entry->objcg, ZSWPWB); - spin_lock(&tree->lock); - zswap_invalidate_entry(tree, entry); - zswap_entry_put(entry); - spin_unlock(&tree->lock); + zswap_entry_free(entry); /* folio is up to date */ folio_mark_uptodate(folio); @@ -1703,7 +1665,7 @@ bool zswap_load(struct folio *folio) spin_unlock(&tree->lock); return false; } - zswap_entry_get(entry); + zswap_rb_erase(&tree->rbroot, entry); spin_unlock(&tree->lock); if (entry->length) @@ -1718,10 +1680,7 @@ bool zswap_load(struct folio *folio) if (entry->objcg) count_objcg_event(entry->objcg, ZSWPIN); - spin_lock(&tree->lock); - zswap_invalidate_entry(tree, entry); - zswap_entry_put(entry); - spin_unlock(&tree->lock); + zswap_entry_free(entry); folio_mark_dirty(folio); |