+static DEFINE_SPINLOCK(nfs_access_lru_lock);
+static LIST_HEAD(nfs_access_lru_list);
+static atomic_long_t nfs_access_nr_entries;
+
+static void nfs_access_free_entry(struct nfs_access_entry *entry)
+{
+ put_rpccred(entry->cred);
+ kfree(entry);
+ smp_mb__before_atomic_dec();
+ atomic_long_dec(&nfs_access_nr_entries);
+ smp_mb__after_atomic_dec();
+}
+
+int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
+{
+ LIST_HEAD(head);
+ struct nfs_inode *nfsi;
+ struct nfs_access_entry *cache;
+
+ spin_lock(&nfs_access_lru_lock);
+restart:
+ list_for_each_entry(nfsi, &nfs_access_lru_list, access_cache_inode_lru) {
+ struct inode *inode;
+
+ if (nr_to_scan-- == 0)
+ break;
+ inode = igrab(&nfsi->vfs_inode);
+ if (inode == NULL)
+ continue;
+ spin_lock(&inode->i_lock);
+ if (list_empty(&nfsi->access_cache_entry_lru))
+ goto remove_lru_entry;
+ cache = list_entry(nfsi->access_cache_entry_lru.next,
+ struct nfs_access_entry, lru);
+ list_move(&cache->lru, &head);
+ rb_erase(&cache->rb_node, &nfsi->access_cache);
+ if (!list_empty(&nfsi->access_cache_entry_lru))
+ list_move_tail(&nfsi->access_cache_inode_lru,
+ &nfs_access_lru_list);
+ else {
+remove_lru_entry:
+ list_del_init(&nfsi->access_cache_inode_lru);
+ clear_bit(NFS_INO_ACL_LRU_SET, &nfsi->flags);
+ }
+ spin_unlock(&inode->i_lock);
+ iput(inode);
+ goto restart;
+ }
+ spin_unlock(&nfs_access_lru_lock);
+ while (!list_empty(&head)) {
+ cache = list_entry(head.next, struct nfs_access_entry, lru);
+ list_del(&cache->lru);
+ nfs_access_free_entry(cache);
+ }
+ return (atomic_long_read(&nfs_access_nr_entries) / 100) * sysctl_vfs_cache_pressure;
+}
+
+static void __nfs_access_zap_cache(struct inode *inode)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+ struct rb_root *root_node = &nfsi->access_cache;
+ struct rb_node *n, *dispose = NULL;
+ struct nfs_access_entry *entry;
+
+ /* Unhook entries from the cache */
+ while ((n = rb_first(root_node)) != NULL) {
+ entry = rb_entry(n, struct nfs_access_entry, rb_node);
+ rb_erase(n, root_node);
+ list_del(&entry->lru);
+ n->rb_left = dispose;
+ dispose = n;
+ }
+ nfsi->cache_validity &= ~NFS_INO_INVALID_ACCESS;
+ spin_unlock(&inode->i_lock);
+
+ /* Now kill them all! */
+ while (dispose != NULL) {
+ n = dispose;
+ dispose = n->rb_left;
+ nfs_access_free_entry(rb_entry(n, struct nfs_access_entry, rb_node));
+ }
+}
+
+void nfs_access_zap_cache(struct inode *inode)
+{
+ /* Remove from global LRU init */
+ if (test_and_clear_bit(NFS_INO_ACL_LRU_SET, &NFS_FLAGS(inode))) {
+ spin_lock(&nfs_access_lru_lock);
+ list_del_init(&NFS_I(inode)->access_cache_inode_lru);
+ spin_unlock(&nfs_access_lru_lock);
+ }
+
+ spin_lock(&inode->i_lock);
+ /* This will release the spinlock */
+ __nfs_access_zap_cache(inode);
+}
+
+static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, struct rpc_cred *cred)
+{
+ struct rb_node *n = NFS_I(inode)->access_cache.rb_node;
+ struct nfs_access_entry *entry;
+
+ while (n != NULL) {
+ entry = rb_entry(n, struct nfs_access_entry, rb_node);
+
+ if (cred < entry->cred)
+ n = n->rb_left;
+ else if (cred > entry->cred)
+ n = n->rb_right;
+ else
+ return entry;
+ }
+ return NULL;
+}
+
+int nfs_access_get_cached(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+ struct nfs_access_entry *cache;
+ int err = -ENOENT;
+
+ spin_lock(&inode->i_lock);
+ if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
+ goto out_zap;
+ cache = nfs_access_search_rbtree(inode, cred);
+ if (cache == NULL)
+ goto out;
+ if (time_after(jiffies, cache->jiffies + NFS_ATTRTIMEO(inode)))
+ goto out_stale;
+ res->jiffies = cache->jiffies;
+ res->cred = cache->cred;
+ res->mask = cache->mask;
+ list_move_tail(&cache->lru, &nfsi->access_cache_entry_lru);
+ err = 0;
+out:
+ spin_unlock(&inode->i_lock);
+ return err;
+out_stale:
+ rb_erase(&cache->rb_node, &nfsi->access_cache);
+ list_del(&cache->lru);
+ spin_unlock(&inode->i_lock);
+ nfs_access_free_entry(cache);
+ return -ENOENT;
+out_zap:
+ /* This will release the spinlock */
+ __nfs_access_zap_cache(inode);
+ return -ENOENT;
+}
+
+static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+ struct rb_root *root_node = &nfsi->access_cache;
+ struct rb_node **p = &root_node->rb_node;
+ struct rb_node *parent = NULL;
+ struct nfs_access_entry *entry;
+
+ spin_lock(&inode->i_lock);
+ while (*p != NULL) {
+ parent = *p;
+ entry = rb_entry(parent, struct nfs_access_entry, rb_node);
+
+ if (set->cred < entry->cred)
+ p = &parent->rb_left;
+ else if (set->cred > entry->cred)
+ p = &parent->rb_right;
+ else
+ goto found;
+ }
+ rb_link_node(&set->rb_node, parent, p);
+ rb_insert_color(&set->rb_node, root_node);
+ list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
+ spin_unlock(&inode->i_lock);
+ return;
+found:
+ rb_replace_node(parent, &set->rb_node, root_node);
+ list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
+ list_del(&entry->lru);
+ spin_unlock(&inode->i_lock);
+ nfs_access_free_entry(entry);
+}
+
+void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
+{
+ struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
+ if (cache == NULL)
+ return;
+ RB_CLEAR_NODE(&cache->rb_node);
+ cache->jiffies = set->jiffies;
+ cache->cred = get_rpccred(set->cred);
+ cache->mask = set->mask;
+
+ nfs_access_add_rbtree(inode, cache);
+
+ /* Update accounting */
+ smp_mb__before_atomic_inc();
+ atomic_long_inc(&nfs_access_nr_entries);
+ smp_mb__after_atomic_inc();
+
+ /* Add inode to global LRU list */
+ if (!test_and_set_bit(NFS_INO_ACL_LRU_SET, &NFS_FLAGS(inode))) {
+ spin_lock(&nfs_access_lru_lock);
+ list_add_tail(&NFS_I(inode)->access_cache_inode_lru, &nfs_access_lru_list);
+ spin_unlock(&nfs_access_lru_lock);
+ }
+}
+
+static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask)
+{
+ struct nfs_access_entry cache;
+ int status;
+
+ status = nfs_access_get_cached(inode, cred, &cache);
+ if (status == 0)
+ goto out;
+
+ /* Be clever: ask server to check for all possible rights */
+ cache.mask = MAY_EXEC | MAY_WRITE | MAY_READ;
+ cache.cred = cred;
+ cache.jiffies = jiffies;
+ status = NFS_PROTO(inode)->access(inode, &cache);
+ if (status != 0)
+ return status;
+ nfs_access_add_cache(inode, &cache);
+out:
+ if ((cache.mask & mask) == mask)
+ return 0;
+ return -EACCES;
+}
+
+int nfs_permission(struct inode *inode, int mask, struct nameidata *nd)