Subversion Repositories HelenOS

Rev

Rev 3386 | Rev 4581 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
2590 jermar 1
/*
2691 jermar 2
 * Copyright (c) 2008 Jakub Jermar
2590 jermar 3
 * All rights reserved.
4
 *
5
 * Redistribution and use in source and binary forms, with or without
6
 * modification, are permitted provided that the following conditions
7
 * are met:
8
 *
9
 * - Redistributions of source code must retain the above copyright
10
 *   notice, this list of conditions and the following disclaimer.
11
 * - Redistributions in binary form must reproduce the above copyright
12
 *   notice, this list of conditions and the following disclaimer in the
13
 *   documentation and/or other materials provided with the distribution.
14
 * - The name of the author may not be used to endorse or promote products
15
 *   derived from this software without specific prior written permission.
16
 *
17
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
 */
28
 
29
/** @addtogroup fs
30
 * @{
31
 */
32
 
33
/**
34
 * @file    vfs_node.c
35
 * @brief   Various operations on VFS nodes have their home in this file.
36
 */
37
 
38
#include "vfs.h"
2596 jermar 39
#include <stdlib.h>
40
#include <string.h>
41
#include <futex.h>
2680 jermar 42
#include <rwlock.h>
2596 jermar 43
#include <libadt/hash_table.h>
2687 jermar 44
#include <assert.h>
2731 jermar 45
#include <async.h>
46
#include <errno.h>
2590 jermar 47
 
2596 jermar 48
/** Futex protecting the VFS node hash table. */
2766 jermar 49
futex_t nodes_futex = FUTEX_INITIALIZER;
2596 jermar 50
 
51
#define NODES_BUCKETS_LOG   8
52
#define NODES_BUCKETS       (1 << NODES_BUCKETS_LOG)
53
 
54
/** VFS node hash table containing all active, in-memory VFS nodes. */
55
hash_table_t nodes;
56
 
57
#define KEY_FS_HANDLE   0
58
#define KEY_DEV_HANDLE  1
59
#define KEY_INDEX   2
60
 
61
static hash_index_t nodes_hash(unsigned long []);
62
static int nodes_compare(unsigned long [], hash_count_t, link_t *);
63
static void nodes_remove_callback(link_t *);
64
 
65
/** VFS node hash table operations. */
66
hash_table_operations_t nodes_ops = {
67
    .hash = nodes_hash,
68
    .compare = nodes_compare,
69
    .remove_callback = nodes_remove_callback
70
};
71
 
72
/** Initialize the VFS node hash table.
73
 *
74
 * @return      Return true on success, false on failure.
75
 */
76
bool vfs_nodes_init(void)
77
{
78
    return hash_table_create(&nodes, NODES_BUCKETS, 3, &nodes_ops);
79
}
80
 
81
static inline void _vfs_node_addref(vfs_node_t *node)
82
{
83
    node->refcnt++;
84
}
85
 
2593 jermar 86
/** Increment reference count of a VFS node.
87
 *
88
 * @param node      VFS node that will have its refcnt incremented.
89
 */
90
void vfs_node_addref(vfs_node_t *node)
91
{
2596 jermar 92
    futex_down(&nodes_futex);
93
    _vfs_node_addref(node);
94
    futex_up(&nodes_futex);
2593 jermar 95
}
96
 
97
/** Decrement reference count of a VFS node.
98
 *
99
 * This function handles the case when the reference count drops to zero.
100
 *
101
 * @param node      VFS node that will have its refcnt decremented.
102
 */
103
void vfs_node_delref(vfs_node_t *node)
104
{
2731 jermar 105
    bool free_vfs_node = false;
106
    bool free_fs_node = false;
107
 
2596 jermar 108
    futex_down(&nodes_futex);
109
    if (node->refcnt-- == 1) {
2731 jermar 110
        /*
111
         * We are dropping the last reference to this node.
112
         * Remove it from the VFS node hash table.
113
         */
2596 jermar 114
        unsigned long key[] = {
115
            [KEY_FS_HANDLE] = node->fs_handle,
116
            [KEY_DEV_HANDLE] = node->dev_handle,
117
            [KEY_INDEX] = node->index
118
        };
119
        hash_table_remove(&nodes, key, 3);
2731 jermar 120
        free_vfs_node = true;
121
        if (!node->lnkcnt)
122
            free_fs_node = true;
2596 jermar 123
    }
124
    futex_up(&nodes_futex);
2731 jermar 125
 
126
    if (free_fs_node) {
127
        /*
128
         * The node is not visible in the file system namespace.
129
         * Free up its resources.
130
         */
131
        int phone = vfs_grab_phone(node->fs_handle);
132
        ipcarg_t rc;
2742 jermar 133
        rc = async_req_2_0(phone, VFS_DESTROY,
134
            (ipcarg_t)node->dev_handle, (ipcarg_t)node->index);
2731 jermar 135
        assert(rc == EOK);
136
        vfs_release_phone(phone);
137
    }
138
    if (free_vfs_node)
139
        free(node);
2593 jermar 140
}
141
 
142
/** Find VFS node.
143
 *
144
 * This function will try to lookup the given triplet in the VFS node hash
145
 * table. In case the triplet is not found there, a new VFS node is created.
146
 * In any case, the VFS node will have its reference count incremented. Every
147
 * node returned by this call should be eventually put back by calling
148
 * vfs_node_put() on it.
149
 *
2691 jermar 150
 * @param result    Populated lookup result structure.
2593 jermar 151
 *
152
 * @return      VFS node corresponding to the given triplet.
153
 */
2691 jermar 154
vfs_node_t *vfs_node_get(vfs_lookup_res_t *result)
2590 jermar 155
{
2596 jermar 156
    unsigned long key[] = {
2691 jermar 157
        [KEY_FS_HANDLE] = result->triplet.fs_handle,
158
        [KEY_DEV_HANDLE] = result->triplet.dev_handle,
159
        [KEY_INDEX] = result->triplet.index
2596 jermar 160
    };
161
    link_t *tmp;
162
    vfs_node_t *node;
163
 
164
    futex_down(&nodes_futex);
165
    tmp = hash_table_find(&nodes, key);
166
    if (!tmp) {
167
        node = (vfs_node_t *) malloc(sizeof(vfs_node_t));
168
        if (!node) {
169
            futex_up(&nodes_futex);
170
            return NULL;
171
        }
172
        memset(node, 0, sizeof(vfs_node_t));
2691 jermar 173
        node->fs_handle = result->triplet.fs_handle;
2740 jermar 174
        node->dev_handle = result->triplet.dev_handle;
2691 jermar 175
        node->index = result->triplet.index;
176
        node->size = result->size;
2730 jermar 177
        node->lnkcnt = result->lnkcnt;
4153 mejdrech 178
        node->type = result->type;
2596 jermar 179
        link_initialize(&node->nh_link);
2680 jermar 180
        rwlock_initialize(&node->contents_rwlock);
2596 jermar 181
        hash_table_insert(&nodes, key, &node->nh_link);
182
    } else {
183
        node = hash_table_get_instance(tmp, vfs_node_t, nh_link);  
4153 mejdrech 184
        if (node->type == VFS_NODE_UNKNOWN &&
185
            result->type != VFS_NODE_UNKNOWN) {
186
            /* Upgrade the node type. */
187
            node->type = result->type;
188
        }
2596 jermar 189
    }
2687 jermar 190
 
2691 jermar 191
    assert(node->size == result->size);
2730 jermar 192
    assert(node->lnkcnt == result->lnkcnt);
4153 mejdrech 193
    assert(node->type == result->type || result->type == VFS_NODE_UNKNOWN);
2687 jermar 194
 
2596 jermar 195
    _vfs_node_addref(node);
196
    futex_up(&nodes_futex);
197
 
198
    return node;
2590 jermar 199
}
200
 
2593 jermar 201
/** Return VFS node when no longer needed by the caller.
202
 *
203
 * This function will remove the reference on the VFS node created by
204
 * vfs_node_get(). This function can only be called as a closing bracket to the
205
 * preceding vfs_node_get() call.
206
 *
207
 * @param node      VFS node being released.
208
 */
209
void vfs_node_put(vfs_node_t *node)
210
{
211
    vfs_node_delref(node);
212
}
213
 
2596 jermar 214
hash_index_t nodes_hash(unsigned long key[])
215
{
216
    hash_index_t a = key[KEY_FS_HANDLE] << (NODES_BUCKETS_LOG / 4);
217
    hash_index_t b = (a | key[KEY_DEV_HANDLE]) << (NODES_BUCKETS_LOG / 2);
218
 
2652 jermar 219
    return (b | key[KEY_INDEX]) & (NODES_BUCKETS - 1);
2596 jermar 220
}
221
 
222
int nodes_compare(unsigned long key[], hash_count_t keys, link_t *item)
223
{
224
    vfs_node_t *node = hash_table_get_instance(item, vfs_node_t, nh_link);
225
    return (node->fs_handle == key[KEY_FS_HANDLE]) &&
226
        (node->dev_handle == key[KEY_DEV_HANDLE]) &&
227
        (node->index == key[KEY_INDEX]);
228
}
229
 
230
void nodes_remove_callback(link_t *item)
231
{
232
}
233
 
2590 jermar 234
/**
235
 * @}
236
 */