WebSVN – HelenOS – Diff – /trunk/uspace/srv/vfs/vfs_node.c

 /*
  * Copyright (c) 2007 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup fs
  * @{
  */
 /**
  * @file    vfs_node.c
  * @brief   Various operations on VFS nodes have their home in this file.
  */
 #include "vfs.h"
+#include <stdlib.h>
+#include <string.h>
+#include <atomic.h>
+#include <futex.h>
+#include <libadt/hash_table.h>
+/** Futex protecting the VFS node hash table. */
+atomic_t nodes_futex = FUTEX_INITIALIZER;
+#define NODES_BUCKETS_LOG   8
+#define NODES_BUCKETS       (1 << NODES_BUCKETS_LOG)
+/** VFS node hash table containing all active, in-memory VFS nodes. */
+hash_table_t nodes;
+#define KEY_FS_HANDLE   0
+#define KEY_DEV_HANDLE  1
+#define KEY_INDEX   2
+static hash_index_t nodes_hash(unsigned long []);
+static int nodes_compare(unsigned long [], hash_count_t, link_t *);
+static void nodes_remove_callback(link_t *);
+/** VFS node hash table operations. */
+hash_table_operations_t nodes_ops = {
+    .hash = nodes_hash,
+    .compare = nodes_compare,
+    .remove_callback = nodes_remove_callback
+};
+/** Initialize the VFS node hash table.
+ *
+ * @return      Return true on success, false on failure.
+ */
+bool vfs_nodes_init(void)
+{
+    return hash_table_create(&nodes, NODES_BUCKETS, 3, &nodes_ops);
+}
+static inline void _vfs_node_addref(vfs_node_t *node)
+{
+    node->refcnt++;
+}
 /** Increment reference count of a VFS node.
+ *
  * @param node      VFS node that will have its refcnt incremented.
  */
 void vfs_node_addref(vfs_node_t *node)
+{
+    futex_down(&nodes_futex);
+    _vfs_node_addref(node);
-    /* TODO */
+    futex_up(&nodes_futex);
+}
 /** Decrement reference count of a VFS node.
+ *
  * This function handles the case when the reference count drops to zero.
+ *
  * @param node      VFS node that will have its refcnt decremented.
  */
 void vfs_node_delref(vfs_node_t *node)
+{
+    futex_down(&nodes_futex);
+    if (node->refcnt-- == 1) {
+        unsigned long key[] = {
+            [KEY_FS_HANDLE] = node->fs_handle,
+            [KEY_DEV_HANDLE] = node->dev_handle,
+            [KEY_INDEX] = node->index
-    /* TODO */
+        };
+        hash_table_remove(&nodes, key, 3);
+    }
+    futex_up(&nodes_futex);
+}
 /** Find VFS node.
+ *
  * This function will try to lookup the given triplet in the VFS node hash
  * table. In case the triplet is not found there, a new VFS node is created.
  * In any case, the VFS node will have its reference count incremented. Every
  * node returned by this call should be eventually put back by calling
  * vfs_node_put() on it.
+ *
  * @param triplet   Triplet encoding the identity of the VFS node.
+ *
  * @return      VFS node corresponding to the given triplet.
  */
 vfs_node_t *vfs_node_get(vfs_triplet_t *triplet)
+{
+    unsigned long key[] = {
+        [KEY_FS_HANDLE] = triplet->fs_handle,
+        [KEY_DEV_HANDLE] = triplet->dev_handle,
+        [KEY_INDEX] = triplet->index
+    };
+    link_t *tmp;
+    vfs_node_t *node;
+    futex_down(&nodes_futex);
+    tmp = hash_table_find(&nodes, key);
-    /* TODO */
+    if (!tmp) {
+        node = (vfs_node_t *) malloc(sizeof(vfs_node_t));
+        if (!node) {
+            futex_up(&nodes_futex);
-    return NULL;
+            return NULL;
+        }
+        memset(node, 0, sizeof(vfs_node_t));
+        node->fs_handle = triplet->fs_handle;
+        node->dev_handle = triplet->fs_handle;
+        node->index = triplet->index;
+        link_initialize(&node->nh_link);
+        hash_table_insert(&nodes, key, &node->nh_link);
+    } else {
+        node = hash_table_get_instance(tmp, vfs_node_t, nh_link);
+    }
+    _vfs_node_addref(node);
+    futex_up(&nodes_futex);
+    return node;
+}
 /** Return VFS node when no longer needed by the caller.
+ *
  * This function will remove the reference on the VFS node created by
  * vfs_node_get(). This function can only be called as a closing bracket to the
  * preceding vfs_node_get() call.
+ *
  * @param node      VFS node being released.
  */
 void vfs_node_put(vfs_node_t *node)
+{
     vfs_node_delref(node);
+}
+hash_index_t nodes_hash(unsigned long key[])
+{
+    hash_index_t a = key[KEY_FS_HANDLE] << (NODES_BUCKETS_LOG / 4);
+    hash_index_t b = (a | key[KEY_DEV_HANDLE]) << (NODES_BUCKETS_LOG / 2);
+    return (b | key[KEY_INDEX]) & ~(NODES_BUCKETS - 1);
+}
+int nodes_compare(unsigned long key[], hash_count_t keys, link_t *item)
+{
+    vfs_node_t *node = hash_table_get_instance(item, vfs_node_t, nh_link);
+    return (node->fs_handle == key[KEY_FS_HANDLE]) &&
+        (node->dev_handle == key[KEY_DEV_HANDLE]) &&
+        (node->index == key[KEY_INDEX]);
+}
+void nodes_remove_callback(link_t *item)
+{
+    vfs_node_t *node = hash_table_get_instance(item, vfs_node_t, nh_link);
+    free(node);
+}
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/vfs/vfs_node.c – Rev 2593 → 2596