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1 | /* |
1 | /* |
2 | * Copyright (c) 2007 Jakub Jermar |
2 | * Copyright (c) 2007 Jakub Jermar |
3 | * All rights reserved. |
3 | * All rights reserved. |
4 | * |
4 | * |
5 | * Redistribution and use in source and binary forms, with or without |
5 | * Redistribution and use in source and binary forms, with or without |
6 | * modification, are permitted provided that the following conditions |
6 | * modification, are permitted provided that the following conditions |
7 | * are met: |
7 | * are met: |
8 | * |
8 | * |
9 | * - Redistributions of source code must retain the above copyright |
9 | * - Redistributions of source code must retain the above copyright |
10 | * notice, this list of conditions and the following disclaimer. |
10 | * notice, this list of conditions and the following disclaimer. |
11 | * - Redistributions in binary form must reproduce the above copyright |
11 | * - Redistributions in binary form must reproduce the above copyright |
12 | * notice, this list of conditions and the following disclaimer in the |
12 | * notice, this list of conditions and the following disclaimer in the |
13 | * documentation and/or other materials provided with the distribution. |
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 |
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. |
15 | * derived from this software without specific prior written permission. |
16 | * |
16 | * |
17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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 |
18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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 |
23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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 |
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. |
26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
27 | */ |
27 | */ |
28 | 28 | ||
29 | /** @addtogroup fs |
29 | /** @addtogroup fs |
30 | * @{ |
30 | * @{ |
31 | */ |
31 | */ |
32 | 32 | ||
33 | /** |
33 | /** |
34 | * @file vfs_node.c |
34 | * @file vfs_node.c |
35 | * @brief Various operations on VFS nodes have their home in this file. |
35 | * @brief Various operations on VFS nodes have their home in this file. |
36 | */ |
36 | */ |
37 | 37 | ||
38 | #include "vfs.h" |
38 | #include "vfs.h" |
- | 39 | #include <stdlib.h> |
|
- | 40 | #include <string.h> |
|
- | 41 | #include <atomic.h> |
|
- | 42 | #include <futex.h> |
|
- | 43 | #include <libadt/hash_table.h> |
|
- | 44 | ||
- | 45 | /** Futex protecting the VFS node hash table. */ |
|
- | 46 | atomic_t nodes_futex = FUTEX_INITIALIZER; |
|
- | 47 | ||
- | 48 | #define NODES_BUCKETS_LOG 8 |
|
- | 49 | #define NODES_BUCKETS (1 << NODES_BUCKETS_LOG) |
|
- | 50 | ||
- | 51 | /** VFS node hash table containing all active, in-memory VFS nodes. */ |
|
- | 52 | hash_table_t nodes; |
|
- | 53 | ||
- | 54 | #define KEY_FS_HANDLE 0 |
|
- | 55 | #define KEY_DEV_HANDLE 1 |
|
- | 56 | #define KEY_INDEX 2 |
|
- | 57 | ||
- | 58 | static hash_index_t nodes_hash(unsigned long []); |
|
- | 59 | static int nodes_compare(unsigned long [], hash_count_t, link_t *); |
|
- | 60 | static void nodes_remove_callback(link_t *); |
|
- | 61 | ||
- | 62 | /** VFS node hash table operations. */ |
|
- | 63 | hash_table_operations_t nodes_ops = { |
|
- | 64 | .hash = nodes_hash, |
|
- | 65 | .compare = nodes_compare, |
|
- | 66 | .remove_callback = nodes_remove_callback |
|
- | 67 | }; |
|
- | 68 | ||
- | 69 | /** Initialize the VFS node hash table. |
|
- | 70 | * |
|
- | 71 | * @return Return true on success, false on failure. |
|
- | 72 | */ |
|
- | 73 | bool vfs_nodes_init(void) |
|
- | 74 | { |
|
- | 75 | return hash_table_create(&nodes, NODES_BUCKETS, 3, &nodes_ops); |
|
- | 76 | } |
|
- | 77 | ||
- | 78 | static inline void _vfs_node_addref(vfs_node_t *node) |
|
- | 79 | { |
|
- | 80 | node->refcnt++; |
|
- | 81 | } |
|
39 | 82 | ||
40 | /** Increment reference count of a VFS node. |
83 | /** Increment reference count of a VFS node. |
41 | * |
84 | * |
42 | * @param node VFS node that will have its refcnt incremented. |
85 | * @param node VFS node that will have its refcnt incremented. |
43 | */ |
86 | */ |
44 | void vfs_node_addref(vfs_node_t *node) |
87 | void vfs_node_addref(vfs_node_t *node) |
45 | { |
88 | { |
- | 89 | futex_down(&nodes_futex); |
|
- | 90 | _vfs_node_addref(node); |
|
46 | /* TODO */ |
91 | futex_up(&nodes_futex); |
47 | } |
92 | } |
48 | 93 | ||
49 | /** Decrement reference count of a VFS node. |
94 | /** Decrement reference count of a VFS node. |
50 | * |
95 | * |
51 | * This function handles the case when the reference count drops to zero. |
96 | * This function handles the case when the reference count drops to zero. |
52 | * |
97 | * |
53 | * @param node VFS node that will have its refcnt decremented. |
98 | * @param node VFS node that will have its refcnt decremented. |
54 | */ |
99 | */ |
55 | void vfs_node_delref(vfs_node_t *node) |
100 | void vfs_node_delref(vfs_node_t *node) |
56 | { |
101 | { |
- | 102 | futex_down(&nodes_futex); |
|
- | 103 | if (node->refcnt-- == 1) { |
|
- | 104 | unsigned long key[] = { |
|
- | 105 | [KEY_FS_HANDLE] = node->fs_handle, |
|
- | 106 | [KEY_DEV_HANDLE] = node->dev_handle, |
|
- | 107 | [KEY_INDEX] = node->index |
|
57 | /* TODO */ |
108 | }; |
- | 109 | hash_table_remove(&nodes, key, 3); |
|
- | 110 | } |
|
- | 111 | futex_up(&nodes_futex); |
|
58 | } |
112 | } |
59 | 113 | ||
60 | /** Find VFS node. |
114 | /** Find VFS node. |
61 | * |
115 | * |
62 | * This function will try to lookup the given triplet in the VFS node hash |
116 | * This function will try to lookup the given triplet in the VFS node hash |
63 | * table. In case the triplet is not found there, a new VFS node is created. |
117 | * table. In case the triplet is not found there, a new VFS node is created. |
64 | * In any case, the VFS node will have its reference count incremented. Every |
118 | * In any case, the VFS node will have its reference count incremented. Every |
65 | * node returned by this call should be eventually put back by calling |
119 | * node returned by this call should be eventually put back by calling |
66 | * vfs_node_put() on it. |
120 | * vfs_node_put() on it. |
67 | * |
121 | * |
68 | * @param triplet Triplet encoding the identity of the VFS node. |
122 | * @param triplet Triplet encoding the identity of the VFS node. |
69 | * |
123 | * |
70 | * @return VFS node corresponding to the given triplet. |
124 | * @return VFS node corresponding to the given triplet. |
71 | */ |
125 | */ |
72 | vfs_node_t *vfs_node_get(vfs_triplet_t *triplet) |
126 | vfs_node_t *vfs_node_get(vfs_triplet_t *triplet) |
73 | { |
127 | { |
- | 128 | unsigned long key[] = { |
|
- | 129 | [KEY_FS_HANDLE] = triplet->fs_handle, |
|
- | 130 | [KEY_DEV_HANDLE] = triplet->dev_handle, |
|
- | 131 | [KEY_INDEX] = triplet->index |
|
- | 132 | }; |
|
- | 133 | link_t *tmp; |
|
- | 134 | vfs_node_t *node; |
|
- | 135 | ||
- | 136 | futex_down(&nodes_futex); |
|
- | 137 | tmp = hash_table_find(&nodes, key); |
|
74 | /* TODO */ |
138 | if (!tmp) { |
- | 139 | node = (vfs_node_t *) malloc(sizeof(vfs_node_t)); |
|
- | 140 | if (!node) { |
|
- | 141 | futex_up(&nodes_futex); |
|
75 | return NULL; |
142 | return NULL; |
- | 143 | } |
|
- | 144 | memset(node, 0, sizeof(vfs_node_t)); |
|
- | 145 | node->fs_handle = triplet->fs_handle; |
|
- | 146 | node->dev_handle = triplet->fs_handle; |
|
- | 147 | node->index = triplet->index; |
|
- | 148 | link_initialize(&node->nh_link); |
|
- | 149 | hash_table_insert(&nodes, key, &node->nh_link); |
|
- | 150 | } else { |
|
- | 151 | node = hash_table_get_instance(tmp, vfs_node_t, nh_link); |
|
- | 152 | } |
|
- | 153 | _vfs_node_addref(node); |
|
- | 154 | futex_up(&nodes_futex); |
|
- | 155 | ||
- | 156 | return node; |
|
76 | } |
157 | } |
77 | 158 | ||
78 | /** Return VFS node when no longer needed by the caller. |
159 | /** Return VFS node when no longer needed by the caller. |
79 | * |
160 | * |
80 | * This function will remove the reference on the VFS node created by |
161 | * This function will remove the reference on the VFS node created by |
81 | * vfs_node_get(). This function can only be called as a closing bracket to the |
162 | * vfs_node_get(). This function can only be called as a closing bracket to the |
82 | * preceding vfs_node_get() call. |
163 | * preceding vfs_node_get() call. |
83 | * |
164 | * |
84 | * @param node VFS node being released. |
165 | * @param node VFS node being released. |
85 | */ |
166 | */ |
86 | void vfs_node_put(vfs_node_t *node) |
167 | void vfs_node_put(vfs_node_t *node) |
87 | { |
168 | { |
88 | vfs_node_delref(node); |
169 | vfs_node_delref(node); |
89 | } |
170 | } |
- | 171 | ||
- | 172 | hash_index_t nodes_hash(unsigned long key[]) |
|
- | 173 | { |
|
- | 174 | hash_index_t a = key[KEY_FS_HANDLE] << (NODES_BUCKETS_LOG / 4); |
|
- | 175 | hash_index_t b = (a | key[KEY_DEV_HANDLE]) << (NODES_BUCKETS_LOG / 2); |
|
- | 176 | ||
- | 177 | return (b | key[KEY_INDEX]) & ~(NODES_BUCKETS - 1); |
|
- | 178 | } |
|
- | 179 | ||
- | 180 | int nodes_compare(unsigned long key[], hash_count_t keys, link_t *item) |
|
- | 181 | { |
|
- | 182 | vfs_node_t *node = hash_table_get_instance(item, vfs_node_t, nh_link); |
|
- | 183 | return (node->fs_handle == key[KEY_FS_HANDLE]) && |
|
- | 184 | (node->dev_handle == key[KEY_DEV_HANDLE]) && |
|
- | 185 | (node->index == key[KEY_INDEX]); |
|
- | 186 | } |
|
- | 187 | ||
- | 188 | void nodes_remove_callback(link_t *item) |
|
- | 189 | { |
|
- | 190 | vfs_node_t *node = hash_table_get_instance(item, vfs_node_t, nh_link); |
|
- | 191 | free(node); |
|
- | 192 | } |
|
90 | 193 | ||
91 | /** |
194 | /** |
92 | * @} |
195 | * @} |
93 | */ |
196 | */ |
94 | 197 |