vfs_dirhash.c revision 1.12.20.1
1 /* $NetBSD: vfs_dirhash.c,v 1.12.20.1 2019/06/10 22:09:04 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2008 Reinoud Zandijk 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 30 #include <sys/cdefs.h> 31 __KERNEL_RCSID(0, "$NetBSD: vfs_dirhash.c,v 1.12.20.1 2019/06/10 22:09:04 christos Exp $"); 32 33 /* CLEAN UP! */ 34 #include <sys/param.h> 35 #include <sys/kernel.h> 36 #include <sys/buf.h> 37 #include <sys/dirent.h> 38 #include <sys/hash.h> 39 #include <sys/mutex.h> 40 #include <sys/pool.h> 41 #include <sys/queue.h> 42 #include <sys/vnode.h> 43 #include <sys/sysctl.h> 44 45 #include <sys/dirhash.h> 46 47 #if 1 48 # define DPRINTF(a) ; 49 #else 50 # define DPRINTF(a) printf a; 51 #endif 52 53 /* 54 * The locking protocol of the dirhash structures is fairly simple: 55 * 56 * The global dirhash_queue is protected by the dirhashmutex. This lock is 57 * internal only and is FS/mountpoint/vnode independent. On exit of the 58 * exported functions this mutex is not helt. 59 * 60 * The dirhash structure is considered part of the vnode/inode/udf_node 61 * structure and will thus use the lock that protects that vnode/inode. 62 * 63 * The dirhash entries are considered part of the dirhash structure and thus 64 * are on the same lock. 65 */ 66 67 static struct sysctllog *sysctl_log; 68 static struct pool dirhash_pool; 69 static struct pool dirhash_entry_pool; 70 71 static kmutex_t dirhashmutex; 72 static uint32_t maxdirhashsize = DIRHASH_SIZE; 73 static uint32_t dirhashsize = 0; 74 static TAILQ_HEAD(_dirhash, dirhash) dirhash_queue; 75 76 77 void 78 dirhash_init(void) 79 { 80 const struct sysctlnode *rnode, *cnode; 81 size_t sz; 82 uint32_t max_entries; 83 84 /* initialise dirhash queue */ 85 TAILQ_INIT(&dirhash_queue); 86 87 /* init dirhash pools */ 88 sz = sizeof(struct dirhash); 89 pool_init(&dirhash_pool, sz, 0, 0, 0, 90 "dirhpl", NULL, IPL_NONE); 91 92 sz = sizeof(struct dirhash_entry); 93 pool_init(&dirhash_entry_pool, sz, 0, 0, 0, 94 "dirhepl", NULL, IPL_NONE); 95 96 mutex_init(&dirhashmutex, MUTEX_DEFAULT, IPL_NONE); 97 max_entries = maxdirhashsize / sz; 98 pool_sethiwat(&dirhash_entry_pool, max_entries); 99 dirhashsize = 0; 100 101 /* create sysctl knobs and dials */ 102 sysctl_log = NULL; 103 sysctl_createv(&sysctl_log, 0, NULL, &rnode, 104 CTLFLAG_PERMANENT, 105 CTLTYPE_NODE, "dirhash", NULL, 106 NULL, 0, NULL, 0, 107 CTL_VFS, VFS_GENERIC, CTL_CREATE, CTL_EOL); 108 sysctl_createv(&sysctl_log, 0, &rnode, &cnode, 109 CTLFLAG_PERMANENT, 110 CTLTYPE_INT, "memused", 111 SYSCTL_DESCR("current dirhash memory usage"), 112 NULL, 0, &dirhashsize, 0, 113 CTL_CREATE, CTL_EOL); 114 sysctl_createv(&sysctl_log, 0, &rnode, &cnode, 115 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 116 CTLTYPE_INT, "maxmem", 117 SYSCTL_DESCR("maximum dirhash memory usage"), 118 NULL, 0, &maxdirhashsize, 0, 119 CTL_CREATE, CTL_EOL); 120 } 121 122 123 #if 0 124 void 125 dirhash_finish(void) 126 { 127 pool_destroy(&dirhash_pool); 128 pool_destroy(&dirhash_entry_pool); 129 130 mutex_destroy(&dirhashmutex); 131 132 /* sysctl_teardown(&sysctl_log); */ 133 } 134 #endif 135 136 137 /* 138 * generic dirhash implementation 139 */ 140 141 void 142 dirhash_purge_entries(struct dirhash *dirh) 143 { 144 struct dirhash_entry *dirh_e; 145 uint32_t hashline; 146 147 if (dirh == NULL) 148 return; 149 150 if (dirh->size == 0) 151 return; 152 153 for (hashline = 0; hashline < DIRHASH_HASHSIZE; hashline++) { 154 while ((dirh_e = 155 LIST_FIRST(&dirh->entries[hashline])) != NULL) { 156 LIST_REMOVE(dirh_e, next); 157 pool_put(&dirhash_entry_pool, dirh_e); 158 } 159 } 160 161 while ((dirh_e = LIST_FIRST(&dirh->free_entries)) != NULL) { 162 LIST_REMOVE(dirh_e, next); 163 pool_put(&dirhash_entry_pool, dirh_e); 164 } 165 166 dirh->flags &= ~DIRH_COMPLETE; 167 dirh->flags |= DIRH_PURGED; 168 dirh->num_files = 0; 169 170 dirhashsize -= dirh->size; 171 dirh->size = 0; 172 } 173 174 175 void 176 dirhash_purge(struct dirhash **dirhp) 177 { 178 struct dirhash *dirh = *dirhp; 179 180 if (dirh == NULL) 181 return; 182 183 /* purge its entries */ 184 dirhash_purge_entries(dirh); 185 186 /* recycle */ 187 mutex_enter(&dirhashmutex); 188 TAILQ_REMOVE(&dirhash_queue, dirh, next); 189 mutex_exit(&dirhashmutex); 190 191 pool_put(&dirhash_pool, dirh); 192 *dirhp = NULL; 193 } 194 195 196 void 197 dirhash_get(struct dirhash **dirhp) 198 { 199 struct dirhash *dirh; 200 uint32_t hashline; 201 202 /* if no dirhash was given, allocate one */ 203 dirh = *dirhp; 204 if (dirh == NULL) { 205 dirh = pool_get(&dirhash_pool, PR_WAITOK | PR_ZERO); 206 for (hashline = 0; hashline < DIRHASH_HASHSIZE; hashline++) { 207 LIST_INIT(&dirh->entries[hashline]); 208 } 209 } 210 211 /* implement LRU on the dirhash queue */ 212 mutex_enter(&dirhashmutex); 213 if (*dirhp) { 214 /* remove from queue to be requeued */ 215 TAILQ_REMOVE(&dirhash_queue, dirh, next); 216 } 217 dirh->refcnt++; 218 TAILQ_INSERT_HEAD(&dirhash_queue, dirh, next); 219 mutex_exit(&dirhashmutex); 220 221 *dirhp = dirh; 222 } 223 224 225 void 226 dirhash_put(struct dirhash *dirh) 227 { 228 229 mutex_enter(&dirhashmutex); 230 dirh->refcnt--; 231 mutex_exit(&dirhashmutex); 232 } 233 234 235 void 236 dirhash_enter(struct dirhash *dirh, 237 struct dirent *dirent, uint64_t offset, uint32_t entry_size, int new_p) 238 { 239 struct dirhash *del_dirh, *prev_dirh; 240 struct dirhash_entry *dirh_e; 241 uint32_t hashvalue, hashline; 242 int entrysize; 243 244 /* make sure we have a dirhash to work on */ 245 KASSERT(dirh); 246 KASSERT(dirh->refcnt > 0); 247 248 /* are we trying to re-enter an entry? */ 249 if (!new_p && (dirh->flags & DIRH_COMPLETE)) 250 return; 251 252 /* calculate our hash */ 253 hashvalue = hash32_strn(dirent->d_name, dirent->d_namlen, HASH32_STR_INIT); 254 hashline = hashvalue & DIRHASH_HASHMASK; 255 256 /* lookup and insert entry if not there yet */ 257 LIST_FOREACH(dirh_e, &dirh->entries[hashline], next) { 258 /* check for hash collision */ 259 if (dirh_e->hashvalue != hashvalue) 260 continue; 261 if (dirh_e->offset != offset) 262 continue; 263 /* got it already */ 264 KASSERT(dirh_e->d_namlen == dirent->d_namlen); 265 KASSERT(dirh_e->entry_size == entry_size); 266 return; 267 } 268 269 DPRINTF(("dirhash enter %"PRIu64", %d, %d for `%*.*s`\n", 270 offset, entry_size, dirent->d_namlen, 271 dirent->d_namlen, dirent->d_namlen, dirent->d_name)); 272 273 /* check if entry is in free space list */ 274 LIST_FOREACH(dirh_e, &dirh->free_entries, next) { 275 if (dirh_e->offset == offset) { 276 DPRINTF(("\tremoving free entry\n")); 277 LIST_REMOVE(dirh_e, next); 278 pool_put(&dirhash_entry_pool, dirh_e); 279 break; 280 } 281 } 282 283 /* ensure we are not passing the dirhash limit */ 284 entrysize = sizeof(struct dirhash_entry); 285 if (dirhashsize + entrysize > maxdirhashsize) { 286 /* we walk the dirhash_queue, so need to lock it */ 287 mutex_enter(&dirhashmutex); 288 del_dirh = TAILQ_LAST(&dirhash_queue, _dirhash); 289 KASSERT(del_dirh); 290 while (dirhashsize + entrysize > maxdirhashsize) { 291 /* no use trying to delete myself */ 292 if (del_dirh == dirh) 293 break; 294 prev_dirh = TAILQ_PREV(del_dirh, _dirhash, next); 295 if (del_dirh->refcnt == 0) 296 dirhash_purge_entries(del_dirh); 297 del_dirh = prev_dirh; 298 } 299 mutex_exit(&dirhashmutex); 300 } 301 302 /* add to the hashline */ 303 dirh_e = pool_get(&dirhash_entry_pool, PR_WAITOK | PR_ZERO); 304 305 dirh_e->hashvalue = hashvalue; 306 dirh_e->offset = offset; 307 dirh_e->d_namlen = dirent->d_namlen; 308 dirh_e->entry_size = entry_size; 309 310 dirh->size += sizeof(struct dirhash_entry); 311 dirh->num_files++; 312 dirhashsize += sizeof(struct dirhash_entry); 313 LIST_INSERT_HEAD(&dirh->entries[hashline], dirh_e, next); 314 } 315 316 317 void 318 dirhash_enter_freed(struct dirhash *dirh, uint64_t offset, 319 uint32_t entry_size) 320 { 321 struct dirhash_entry *dirh_e; 322 323 /* make sure we have a dirhash to work on */ 324 KASSERT(dirh); 325 KASSERT(dirh->refcnt > 0); 326 327 /* check for double entry of free space */ 328 LIST_FOREACH(dirh_e, &dirh->free_entries, next) { 329 KASSERT(dirh_e->offset != offset); 330 } 331 332 DPRINTF(("dirhash enter FREED %"PRIu64", %d\n", 333 offset, entry_size)); 334 dirh_e = pool_get(&dirhash_entry_pool, PR_WAITOK | PR_ZERO); 335 336 dirh_e->hashvalue = 0; /* not relevant */ 337 dirh_e->offset = offset; 338 dirh_e->d_namlen = 0; /* not relevant */ 339 dirh_e->entry_size = entry_size; 340 341 /* XXX it might be preferable to append them at the tail */ 342 LIST_INSERT_HEAD(&dirh->free_entries, dirh_e, next); 343 dirh->size += sizeof(struct dirhash_entry); 344 dirhashsize += sizeof(struct dirhash_entry); 345 } 346 347 348 void 349 dirhash_remove(struct dirhash *dirh, struct dirent *dirent, 350 uint64_t offset, uint32_t entry_size) 351 { 352 struct dirhash_entry *dirh_e; 353 uint32_t hashvalue, hashline; 354 355 DPRINTF(("dirhash remove %"PRIu64", %d for `%*.*s`\n", 356 offset, entry_size, 357 dirent->d_namlen, dirent->d_namlen, dirent->d_name)); 358 359 /* make sure we have a dirhash to work on */ 360 KASSERT(dirh); 361 KASSERT(dirh->refcnt > 0); 362 363 /* calculate our hash */ 364 hashvalue = hash32_strn(dirent->d_name, dirent->d_namlen, HASH32_STR_INIT); 365 hashline = hashvalue & DIRHASH_HASHMASK; 366 367 /* lookup entry */ 368 LIST_FOREACH(dirh_e, &dirh->entries[hashline], next) { 369 /* check for hash collision */ 370 if (dirh_e->hashvalue != hashvalue) 371 continue; 372 if (dirh_e->offset != offset) 373 continue; 374 375 /* got it! */ 376 KASSERT(dirh_e->d_namlen == dirent->d_namlen); 377 KASSERT(dirh_e->entry_size == entry_size); 378 LIST_REMOVE(dirh_e, next); 379 dirh->size -= sizeof(struct dirhash_entry); 380 KASSERT(dirh->num_files > 0); 381 dirh->num_files--; 382 dirhashsize -= sizeof(struct dirhash_entry); 383 384 dirhash_enter_freed(dirh, offset, entry_size); 385 return; 386 } 387 388 /* not found! */ 389 panic("dirhash_remove couldn't find entry in hash table\n"); 390 } 391 392 393 /* 394 * BUGALERT: don't use result longer than needed, never past the node lock. 395 * Call with NULL *result initially and it will return nonzero if again. 396 */ 397 int 398 dirhash_lookup(struct dirhash *dirh, const char *d_name, int d_namlen, 399 struct dirhash_entry **result) 400 { 401 struct dirhash_entry *dirh_e; 402 uint32_t hashvalue, hashline; 403 404 /* make sure we have a dirhash to work on */ 405 KASSERT(dirh); 406 KASSERT(dirh->refcnt > 0); 407 408 /* start where we were */ 409 if (*result) { 410 dirh_e = *result; 411 412 /* retrieve information to avoid recalculation and advance */ 413 hashvalue = dirh_e->hashvalue; 414 dirh_e = LIST_NEXT(*result, next); 415 } else { 416 /* calculate our hash and lookup all entries in hashline */ 417 hashvalue = hash32_strn(d_name, d_namlen, HASH32_STR_INIT); 418 hashline = hashvalue & DIRHASH_HASHMASK; 419 dirh_e = LIST_FIRST(&dirh->entries[hashline]); 420 } 421 422 for (; dirh_e; dirh_e = LIST_NEXT(dirh_e, next)) { 423 /* check for hash collision */ 424 if (dirh_e->hashvalue != hashvalue) 425 continue; 426 if (dirh_e->d_namlen != d_namlen) 427 continue; 428 /* might have an entry in the cache */ 429 *result = dirh_e; 430 return 1; 431 } 432 433 *result = NULL; 434 return 0; 435 } 436 437 438 /* 439 * BUGALERT: don't use result longer than needed, never past the node lock. 440 * Call with NULL *result initially and it will return nonzero if again. 441 */ 442 443 int 444 dirhash_lookup_freed(struct dirhash *dirh, uint32_t min_entrysize, 445 struct dirhash_entry **result) 446 { 447 struct dirhash_entry *dirh_e; 448 449 /* make sure we have a dirhash to work on */ 450 KASSERT(dirh); 451 KASSERT(dirh->refcnt > 0); 452 453 /* start where we were */ 454 if (*result) { 455 dirh_e = LIST_NEXT(*result, next); 456 } else { 457 /* lookup all entries that match */ 458 dirh_e = LIST_FIRST(&dirh->free_entries); 459 } 460 461 for (; dirh_e; dirh_e = LIST_NEXT(dirh_e, next)) { 462 /* check for minimum size */ 463 if (dirh_e->entry_size < min_entrysize) 464 continue; 465 /* might be a candidate */ 466 *result = dirh_e; 467 return 1; 468 } 469 470 *result = NULL; 471 return 0; 472 } 473 474 475 bool 476 dirhash_dir_isempty(struct dirhash *dirh) 477 { 478 #ifdef DEBUG 479 struct dirhash_entry *dirh_e; 480 int hashline, num; 481 482 num = 0; 483 for (hashline = 0; hashline < DIRHASH_HASHSIZE; hashline++) { 484 LIST_FOREACH(dirh_e, &dirh->entries[hashline], next) { 485 num++; 486 } 487 } 488 489 if (dirh->num_files != num) { 490 printf("dirhash_dir_isempy: dirhash_counter failed: " 491 "dirh->num_files = %d, counted %d\n", 492 dirh->num_files, num); 493 assert(dirh->num_files == num); 494 } 495 #endif 496 /* assert the directory hash info is valid */ 497 KASSERT(dirh->flags & DIRH_COMPLETE); 498 499 /* the directory is empty when only '..' lifes in it or is absent */ 500 return (dirh->num_files <= 1); 501 } 502 503
Indexes created Tue Sep 30 07:10:03 GMT 2025