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1 | /* |
1 | /* |
2 | * Copyright (c) 2008 Jakub Jermar |
2 | * Copyright (c) 2008 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 fat_idx.c |
34 | * @file fat_idx.c |
35 | * @brief Layer for translating FAT entities to VFS node indices. |
35 | * @brief Layer for translating FAT entities to VFS node indices. |
36 | */ |
36 | */ |
37 | 37 | ||
38 | #include "fat.h" |
38 | #include "fat.h" |
39 | #include "../../vfs/vfs.h" |
39 | #include "../../vfs/vfs.h" |
40 | #include <errno.h> |
40 | #include <errno.h> |
41 | #include <string.h> |
41 | #include <string.h> |
42 | #include <libadt/hash_table.h> |
42 | #include <libadt/hash_table.h> |
43 | #include <libadt/list.h> |
43 | #include <libadt/list.h> |
44 | #include <assert.h> |
44 | #include <assert.h> |
45 | #include <futex.h> |
45 | #include <futex.h> |
46 | 46 | ||
47 | /** Each instance of this type describes one interval of freed VFS indices. */ |
47 | /** Each instance of this type describes one interval of freed VFS indices. */ |
48 | typedef struct { |
48 | typedef struct { |
49 | link_t link; |
49 | link_t link; |
50 | fs_index_t first; |
50 | fs_index_t first; |
51 | fs_index_t last; |
51 | fs_index_t last; |
52 | } freed_t; |
52 | } freed_t; |
53 | 53 | ||
54 | /** |
54 | /** |
55 | * Each instance of this type describes state of all VFS indices that |
55 | * Each instance of this type describes state of all VFS indices that |
56 | * are currently unused. |
56 | * are currently unused. |
57 | */ |
57 | */ |
58 | typedef struct { |
58 | typedef struct { |
59 | link_t link; |
59 | link_t link; |
60 | dev_handle_t dev_handle; |
60 | dev_handle_t dev_handle; |
61 | 61 | ||
62 | /** Next unassigned index. */ |
62 | /** Next unassigned index. */ |
63 | fs_index_t next; |
63 | fs_index_t next; |
64 | /** Number of remaining unassigned indices. */ |
64 | /** Number of remaining unassigned indices. */ |
65 | uint64_t remaining; |
65 | uint64_t remaining; |
66 | 66 | ||
67 | /** Sorted list of intervals of freed indices. */ |
67 | /** Sorted list of intervals of freed indices. */ |
68 | link_t freed_head; |
68 | link_t freed_head; |
69 | } unused_t; |
69 | } unused_t; |
70 | 70 | ||
71 | static LIST_INITIALIZE(unused_head); |
71 | static LIST_INITIALIZE(unused_head); |
72 | 72 | ||
- | 73 | /** Global hash table of all used fat_idx_t structures. */ |
|
- | 74 | static hash_table_t used_hash; |
|
- | 75 | ||
- | 76 | #define USED_HASH_BUCKETS_LOG 12 |
|
- | 77 | #define USED_HASH_BUCKETS (1 << USED_HASH_BUCKETS_LOG) |
|
- | 78 | ||
- | 79 | #define USED_HASH_DH_KEY 0 |
|
- | 80 | #define USED_HASH_PFC_KEY 1 |
|
- | 81 | #define USED_HASH_PDI_KEY 2 |
|
- | 82 | ||
- | 83 | static hash_index_t idx_hash(unsigned long key[]) |
|
- | 84 | { |
|
- | 85 | dev_handle_t dev_handle = (dev_handle_t)key[USED_HASH_DH_KEY]; |
|
- | 86 | fat_cluster_t pfc = (fat_cluster_t)key[USED_HASH_PFC_KEY]; |
|
- | 87 | unsigned pdi = (unsigned)key[USED_HASH_PDI_KEY]; |
|
- | 88 | ||
- | 89 | hash_index_t h; |
|
- | 90 | ||
- | 91 | /* |
|
- | 92 | * The least significant half of all bits are the least significant bits |
|
- | 93 | * of the parent node's first cluster. |
|
- | 94 | * |
|
- | 95 | * The least significant half of the most significant half of all bits |
|
- | 96 | * are the least significant bits of the node's dentry index within the |
|
- | 97 | * parent directory node. |
|
- | 98 | * |
|
- | 99 | * The most significant half of the most significant half of all bits |
|
- | 100 | * are the least significant bits of the device handle. |
|
- | 101 | */ |
|
- | 102 | h = pfc & ((USED_HASH_BUCKETS_LOG / 2) - 1); |
|
- | 103 | h |= (pdi & ((USED_HASH_BUCKETS_LOG / 4) - 1)) << |
|
- | 104 | (USED_HASH_BUCKETS_LOG / 2); |
|
- | 105 | h |= (dev_handle & ((USED_HASH_BUCKETS_LOG / 4) - 1)) << |
|
- | 106 | (3 * (USED_HASH_BUCKETS_LOG / 4)); |
|
- | 107 | ||
- | 108 | return h; |
|
- | 109 | } |
|
- | 110 | ||
- | 111 | static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item) |
|
- | 112 | { |
|
- | 113 | dev_handle_t dev_handle = (dev_handle_t)key[USED_HASH_DH_KEY]; |
|
- | 114 | fat_cluster_t pfc = (fat_cluster_t)key[USED_HASH_PFC_KEY]; |
|
- | 115 | unsigned pdi = (unsigned)key[USED_HASH_PDI_KEY]; |
|
- | 116 | fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uh_link); |
|
- | 117 | ||
- | 118 | return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) && |
|
- | 119 | (pdi == fidx->pdi); |
|
- | 120 | } |
|
- | 121 | ||
- | 122 | static void idx_remove_callback(link_t *item) |
|
- | 123 | { |
|
- | 124 | /* nothing to do */ |
|
- | 125 | } |
|
- | 126 | ||
- | 127 | static hash_table_operations_t used_idx_ops = { |
|
- | 128 | .hash = idx_hash, |
|
- | 129 | .compare = idx_compare, |
|
- | 130 | .remove_callback = idx_remove_callback, |
|
- | 131 | }; |
|
- | 132 | ||
73 | /** Allocate a VFS index which is not currently in use. */ |
133 | /** Allocate a VFS index which is not currently in use. */ |
74 | static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index) |
134 | static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index) |
75 | { |
135 | { |
76 | link_t *l; |
136 | link_t *l; |
77 | unused_t *u; |
137 | unused_t *u; |
78 | 138 | ||
79 | assert(index); |
139 | assert(index); |
80 | for (l = unused_head.next; l != &unused_head; l = l->next) { |
140 | for (l = unused_head.next; l != &unused_head; l = l->next) { |
81 | u = list_get_instance(l, unused_t, link); |
141 | u = list_get_instance(l, unused_t, link); |
82 | if (u->dev_handle == dev_handle) |
142 | if (u->dev_handle == dev_handle) |
83 | goto hit; |
143 | goto hit; |
84 | } |
144 | } |
85 | 145 | ||
86 | /* dev_handle not found */ |
146 | /* dev_handle not found */ |
87 | return false; |
147 | return false; |
88 | 148 | ||
89 | hit: |
149 | hit: |
90 | if (list_empty(&u->freed_head)) { |
150 | if (list_empty(&u->freed_head)) { |
91 | if (u->remaining) { |
151 | if (u->remaining) { |
92 | /* |
152 | /* |
93 | * There are no freed indices, allocate one directly |
153 | * There are no freed indices, allocate one directly |
94 | * from the counter. |
154 | * from the counter. |
95 | */ |
155 | */ |
96 | *index = u->next++; |
156 | *index = u->next++; |
97 | --u->remaining; |
157 | --u->remaining; |
98 | return true; |
158 | return true; |
99 | } |
159 | } |
100 | } else { |
160 | } else { |
101 | /* There are some freed indices which we can reuse. */ |
161 | /* There are some freed indices which we can reuse. */ |
102 | freed_t *f = list_get_instance(u->freed_head.next, freed_t, |
162 | freed_t *f = list_get_instance(u->freed_head.next, freed_t, |
103 | link); |
163 | link); |
104 | *index = f->first; |
164 | *index = f->first; |
105 | if (f->first++ == f->last) { |
165 | if (f->first++ == f->last) { |
106 | /* Destroy the interval. */ |
166 | /* Destroy the interval. */ |
107 | list_remove(&f->link); |
167 | list_remove(&f->link); |
108 | free(f); |
168 | free(f); |
109 | } |
169 | } |
110 | return true; |
170 | return true; |
111 | } |
171 | } |
112 | /* |
172 | /* |
113 | * We ran out of indices, which is extremely unlikely with FAT16, but |
173 | * We ran out of indices, which is extremely unlikely with FAT16, but |
114 | * theoretically still possible (e.g. too many open unlinked nodes or |
174 | * theoretically still possible (e.g. too many open unlinked nodes or |
115 | * too many zero-sized nodes). |
175 | * too many zero-sized nodes). |
116 | */ |
176 | */ |
117 | return false; |
177 | return false; |
118 | } |
178 | } |
119 | 179 | ||
120 | /** If possible, coalesce two intervals of freed indices. */ |
180 | /** If possible, coalesce two intervals of freed indices. */ |
121 | static void try_coalesce_intervals(link_t *l, link_t *r, link_t *cur) |
181 | static void try_coalesce_intervals(link_t *l, link_t *r, link_t *cur) |
122 | { |
182 | { |
123 | freed_t *fl = list_get_instance(l, freed_t, link); |
183 | freed_t *fl = list_get_instance(l, freed_t, link); |
124 | freed_t *fr = list_get_instance(r, freed_t, link); |
184 | freed_t *fr = list_get_instance(r, freed_t, link); |
125 | 185 | ||
126 | if (fl->last + 1 == fr->first) { |
186 | if (fl->last + 1 == fr->first) { |
127 | if (cur == l) { |
187 | if (cur == l) { |
128 | fl->last = fr->last; |
188 | fl->last = fr->last; |
129 | list_remove(r); |
189 | list_remove(r); |
130 | free(r); |
190 | free(r); |
131 | } else { |
191 | } else { |
132 | fr->first = fl->first; |
192 | fr->first = fl->first; |
133 | list_remove(l); |
193 | list_remove(l); |
134 | free(l); |
194 | free(l); |
135 | } |
195 | } |
136 | } |
196 | } |
137 | } |
197 | } |
138 | 198 | ||
139 | /** Free a VFS index, which is no longer in use. */ |
199 | /** Free a VFS index, which is no longer in use. */ |
140 | static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index) |
200 | static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index) |
141 | { |
201 | { |
142 | link_t *l; |
202 | link_t *l; |
143 | unused_t *u; |
203 | unused_t *u; |
144 | 204 | ||
145 | for (l = unused_head.next; l != &unused_head; l = l->next) { |
205 | for (l = unused_head.next; l != &unused_head; l = l->next) { |
146 | u = list_get_instance(l, unused_t, link); |
206 | u = list_get_instance(l, unused_t, link); |
147 | if (u->dev_handle == dev_handle) |
207 | if (u->dev_handle == dev_handle) |
148 | goto hit; |
208 | goto hit; |
149 | } |
209 | } |
150 | 210 | ||
151 | /* should not happen */ |
211 | /* should not happen */ |
152 | assert(0); |
212 | assert(0); |
153 | 213 | ||
154 | hit: |
214 | hit: |
155 | if (u->next == index + 1) { |
215 | if (u->next == index + 1) { |
156 | /* The index can be returned directly to the counter. */ |
216 | /* The index can be returned directly to the counter. */ |
157 | u->next--; |
217 | u->next--; |
158 | u->remaining++; |
218 | u->remaining++; |
159 | return; |
219 | return; |
160 | } else { |
220 | } else { |
161 | /* |
221 | /* |
162 | * The index must be returned either to an existing freed |
222 | * The index must be returned either to an existing freed |
163 | * interval or a new interval must be created. |
223 | * interval or a new interval must be created. |
164 | */ |
224 | */ |
165 | link_t *lnk; |
225 | link_t *lnk; |
166 | freed_t *n; |
226 | freed_t *n; |
167 | for (lnk = u->freed_head.next; lnk != &u->freed_head; |
227 | for (lnk = u->freed_head.next; lnk != &u->freed_head; |
168 | lnk = lnk->next) { |
228 | lnk = lnk->next) { |
169 | freed_t *f = list_get_instance(lnk, freed_t, link); |
229 | freed_t *f = list_get_instance(lnk, freed_t, link); |
170 | if (f->first == index + 1) { |
230 | if (f->first == index + 1) { |
171 | f->first--; |
231 | f->first--; |
172 | if (lnk->prev != &u->freed_head) |
232 | if (lnk->prev != &u->freed_head) |
173 | try_coalesce_intervals(lnk->prev, lnk, |
233 | try_coalesce_intervals(lnk->prev, lnk, |
174 | lnk); |
234 | lnk); |
175 | return; |
235 | return; |
176 | } |
236 | } |
177 | if (f->last == index - 1) { |
237 | if (f->last == index - 1) { |
178 | f->last++; |
238 | f->last++; |
179 | if (lnk->next != &u->freed_head) |
239 | if (lnk->next != &u->freed_head) |
180 | try_coalesce_intervals(lnk, lnk->next, |
240 | try_coalesce_intervals(lnk, lnk->next, |
181 | lnk); |
241 | lnk); |
182 | return; |
242 | return; |
183 | } |
243 | } |
184 | if (index > f->first) { |
244 | if (index > f->first) { |
185 | n = malloc(sizeof(freed_t)); |
245 | n = malloc(sizeof(freed_t)); |
186 | /* TODO: sleep until allocation succeeds */ |
246 | /* TODO: sleep until allocation succeeds */ |
187 | assert(n); |
247 | assert(n); |
188 | link_initialize(&n->link); |
248 | link_initialize(&n->link); |
189 | n->first = index; |
249 | n->first = index; |
190 | n->last = index; |
250 | n->last = index; |
191 | list_insert_before(&n->link, lnk); |
251 | list_insert_before(&n->link, lnk); |
192 | return; |
252 | return; |
193 | } |
253 | } |
194 | 254 | ||
195 | } |
255 | } |
196 | /* The index will form the last interval. */ |
256 | /* The index will form the last interval. */ |
197 | n = malloc(sizeof(freed_t)); |
257 | n = malloc(sizeof(freed_t)); |
198 | /* TODO: sleep until allocation succeeds */ |
258 | /* TODO: sleep until allocation succeeds */ |
199 | assert(n); |
259 | assert(n); |
200 | link_initialize(&n->link); |
260 | link_initialize(&n->link); |
201 | n->first = index; |
261 | n->first = index; |
202 | n->last = index; |
262 | n->last = index; |
203 | list_append(&n->link, &u->freed_head); |
263 | list_append(&n->link, &u->freed_head); |
204 | } |
264 | } |
205 | } |
265 | } |
206 | 266 | ||
207 | fat_idx_t *fat_idx_map(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi) |
267 | fat_idx_t *fat_idx_map(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi) |
208 | { |
268 | { |
- | 269 | fat_idx_t *fidx; |
|
- | 270 | link_t *l; |
|
- | 271 | unsigned long key[] = { |
|
- | 272 | [USED_HASH_DH_KEY] = dev_handle, |
|
- | 273 | [USED_HASH_PFC_KEY] = pfc, |
|
- | 274 | [USED_HASH_PDI_KEY] = pdi, |
|
- | 275 | }; |
|
- | 276 | ||
- | 277 | l = hash_table_find(&used_hash, key); |
|
- | 278 | if (l) { |
|
- | 279 | fidx = hash_table_get_instance(l, fat_idx_t, uh_link); |
|
- | 280 | } else { |
|
- | 281 | fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t)); |
|
- | 282 | if (!fidx) { |
|
209 | return NULL; /* TODO */ |
283 | return NULL; |
- | 284 | } |
|
- | 285 | if (!fat_idx_alloc(dev_handle, &fidx->index)) { |
|
- | 286 | free(fidx); |
|
- | 287 | return NULL; |
|
- | 288 | } |
|
- | 289 | link_initialize(&fidx->uh_link); |
|
- | 290 | fidx->dev_handle = dev_handle; |
|
- | 291 | fidx->pfc = pfc; |
|
- | 292 | fidx->pdi = pdi; |
|
- | 293 | fidx->nodep = NULL; |
|
- | 294 | hash_table_insert(&used_hash, key, &fidx->uh_link); |
|
- | 295 | } |
|
- | 296 | ||
- | 297 | return fidx; |
|
210 | } |
298 | } |
- | 299 | ||
211 | 300 |