kern_fileassoc.c revision 1.9.2.4
1 /* $NetBSD: kern_fileassoc.c,v 1.9.2.4 2007/02/09 21:03:53 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 2006 Elad Efrat <elad (at) NetBSD.org> 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 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 __KERNEL_RCSID(0, "$NetBSD: kern_fileassoc.c,v 1.9.2.4 2007/02/09 21:03:53 ad Exp $"); 32 33 #include "opt_fileassoc.h" 34 35 #include <sys/param.h> 36 #include <sys/mount.h> 37 #include <sys/queue.h> 38 #include <sys/malloc.h> 39 #include <sys/vnode.h> 40 #include <sys/namei.h> 41 #include <sys/exec.h> 42 #include <sys/proc.h> 43 #include <sys/inttypes.h> 44 #include <sys/errno.h> 45 #include <sys/fileassoc.h> 46 #include <sys/specificdata.h> 47 #include <sys/hash.h> 48 #include <sys/fstypes.h> 49 #include <sys/kmem.h> 50 #include <sys/once.h> 51 52 #define FILEASSOC_INITIAL_TABLESIZE 128 53 54 static struct fileassoc_hash_entry * 55 fileassoc_file_lookup(struct vnode *, fhandle_t *); 56 static struct fileassoc_hash_entry * 57 fileassoc_file_add(struct vnode *, fhandle_t *); 58 static struct fileassoc_table *fileassoc_table_resize(struct fileassoc_table *); 59 60 static specificdata_domain_t fileassoc_domain; 61 static specificdata_key_t fileassoc_mountspecific_key; 62 63 /* 64 * Hook entry. 65 * Includes the hook name for identification and private hook clear callback. 66 */ 67 struct fileassoc { 68 LIST_ENTRY(fileassoc) list; 69 const char *name; /* name. */ 70 fileassoc_cleanup_cb_t cleanup_cb; /* clear callback. */ 71 specificdata_key_t key; 72 }; 73 74 static LIST_HEAD(, fileassoc) fileassoc_list; 75 76 /* An entry in the per-mount hash table. */ 77 struct fileassoc_hash_entry { 78 fhandle_t *handle; /* File handle */ 79 specificdata_reference data; /* Hooks. */ 80 u_int nassocs; /* # of hooks. */ 81 LIST_ENTRY(fileassoc_hash_entry) entries; /* List pointer. */ 82 }; 83 84 LIST_HEAD(fileassoc_hashhead, fileassoc_hash_entry); 85 86 struct fileassoc_table { 87 struct fileassoc_hashhead *hash_tbl; 88 size_t hash_size; /* Number of slots. */ 89 u_long hash_mask; 90 size_t hash_used; /* # of used slots. */ 91 specificdata_reference data; 92 }; 93 94 /* 95 * Hashing function: Takes a number modulus the mask to give back an 96 * index into the hash table. 97 */ 98 #define FILEASSOC_HASH(tbl, handle) \ 99 (hash32_buf((handle), FHANDLE_SIZE(handle), HASH32_BUF_INIT) \ 100 & ((tbl)->hash_mask)) 101 102 static void * 103 file_getdata(struct fileassoc_hash_entry *e, const struct fileassoc *assoc) 104 { 105 106 return specificdata_getspecific(fileassoc_domain, &e->data, 107 assoc->key); 108 } 109 110 static void 111 file_setdata(struct fileassoc_hash_entry *e, const struct fileassoc *assoc, 112 void *data) 113 { 114 115 specificdata_setspecific(fileassoc_domain, &e->data, assoc->key, 116 data); 117 } 118 119 static void 120 file_cleanup(struct fileassoc_hash_entry *e, const struct fileassoc *assoc) 121 { 122 fileassoc_cleanup_cb_t cb; 123 void *data; 124 125 cb = assoc->cleanup_cb; 126 if (cb == NULL) { 127 return; 128 } 129 data = file_getdata(e, assoc); 130 (*cb)(data); 131 } 132 133 static void 134 file_free(struct fileassoc_hash_entry *e) 135 { 136 struct fileassoc *assoc; 137 138 LIST_REMOVE(e, entries); 139 140 LIST_FOREACH(assoc, &fileassoc_list, list) { 141 file_cleanup(e, assoc); 142 } 143 vfs_composefh_free(e->handle); 144 specificdata_fini(fileassoc_domain, &e->data); 145 kmem_free(e, sizeof(*e)); 146 } 147 148 static void 149 table_dtor(void *vp) 150 { 151 struct fileassoc_table *tbl = vp; 152 struct fileassoc_hashhead *hh; 153 u_long i; 154 155 /* Remove all entries from the table and lists */ 156 hh = tbl->hash_tbl; 157 for (i = 0; i < tbl->hash_size; i++) { 158 struct fileassoc_hash_entry *mhe; 159 160 while ((mhe = LIST_FIRST(&hh[i])) != NULL) { 161 file_free(mhe); 162 } 163 } 164 165 /* Remove hash table and sysctl node */ 166 hashdone(tbl->hash_tbl, M_TEMP); 167 specificdata_fini(fileassoc_domain, &tbl->data); 168 kmem_free(tbl, sizeof(*tbl)); 169 } 170 171 /* 172 * Initialize the fileassoc subsystem. 173 */ 174 static int 175 fileassoc_init(void) 176 { 177 int error; 178 179 error = mount_specific_key_create(&fileassoc_mountspecific_key, 180 table_dtor); 181 if (error) { 182 return error; 183 } 184 fileassoc_domain = specificdata_domain_create(); 185 186 return 0; 187 } 188 189 /* 190 * Register a new hook. 191 */ 192 int 193 fileassoc_register(const char *name, fileassoc_cleanup_cb_t cleanup_cb, 194 fileassoc_t *result) 195 { 196 int error; 197 specificdata_key_t key; 198 struct fileassoc *assoc; 199 static ONCE_DECL(control); 200 201 error = RUN_ONCE(&control, fileassoc_init); 202 if (error) { 203 return error; 204 } 205 error = specificdata_key_create(fileassoc_domain, &key, NULL); 206 if (error) { 207 return error; 208 } 209 assoc = kmem_alloc(sizeof(*assoc), KM_SLEEP); 210 assoc->name = name; 211 assoc->cleanup_cb = cleanup_cb; 212 assoc->key = key; 213 LIST_INSERT_HEAD(&fileassoc_list, assoc, list); 214 *result = assoc; 215 216 return 0; 217 } 218 219 /* 220 * Deregister a hook. 221 */ 222 int 223 fileassoc_deregister(fileassoc_t assoc) 224 { 225 226 LIST_REMOVE(assoc, list); 227 specificdata_key_delete(fileassoc_domain, assoc->key); 228 kmem_free(assoc, sizeof(*assoc)); 229 230 return 0; 231 } 232 233 /* 234 * Get the hash table for the specified device. 235 */ 236 static struct fileassoc_table * 237 fileassoc_table_lookup(struct mount *mp) 238 { 239 240 return mount_getspecific(mp, fileassoc_mountspecific_key); 241 } 242 243 /* 244 * Perform a lookup on a hash table. If hint is non-zero then use the value 245 * of the hint as the identifier instead of performing a lookup for the 246 * fileid. 247 */ 248 static struct fileassoc_hash_entry * 249 fileassoc_file_lookup(struct vnode *vp, fhandle_t *hint) 250 { 251 struct fileassoc_table *tbl; 252 struct fileassoc_hashhead *tble; 253 struct fileassoc_hash_entry *e; 254 size_t indx; 255 fhandle_t *th; 256 int error; 257 258 tbl = fileassoc_table_lookup(vp->v_mount); 259 if (tbl == NULL) { 260 return NULL; 261 } 262 263 if (hint == NULL) { 264 error = vfs_composefh_alloc(vp, &th); 265 if (error) 266 return (NULL); 267 } else { 268 th = hint; 269 } 270 271 indx = FILEASSOC_HASH(tbl, th); 272 tble = &(tbl->hash_tbl[indx]); 273 274 LIST_FOREACH(e, tble, entries) { 275 if (((FHANDLE_FILEID(e->handle)->fid_len == 276 FHANDLE_FILEID(th)->fid_len)) && 277 (memcmp(FHANDLE_FILEID(e->handle), FHANDLE_FILEID(th), 278 (FHANDLE_FILEID(th))->fid_len) == 0)) { 279 break; 280 } 281 } 282 283 if (hint == NULL) 284 vfs_composefh_free(th); 285 286 return e; 287 } 288 289 /* 290 * Return hook data associated with a vnode. 291 */ 292 void * 293 fileassoc_lookup(struct vnode *vp, fileassoc_t assoc) 294 { 295 struct fileassoc_hash_entry *mhe; 296 297 mhe = fileassoc_file_lookup(vp, NULL); 298 if (mhe == NULL) 299 return (NULL); 300 301 return file_getdata(mhe, assoc); 302 } 303 304 static struct fileassoc_table * 305 fileassoc_table_resize(struct fileassoc_table *tbl) 306 { 307 struct fileassoc_table *newtbl; 308 struct fileassoc_hashhead *hh; 309 u_long i; 310 311 /* 312 * Allocate a new table. Like the condition in fileassoc_file_add(), 313 * this is also temporary -- just double the number of slots. 314 */ 315 newtbl = kmem_zalloc(sizeof(*newtbl), KM_SLEEP); 316 newtbl->hash_size = (tbl->hash_size * 2); 317 if (newtbl->hash_size < tbl->hash_size) 318 newtbl->hash_size = tbl->hash_size; 319 newtbl->hash_tbl = hashinit(newtbl->hash_size, HASH_LIST, M_TEMP, 320 M_WAITOK | M_ZERO, &newtbl->hash_mask); 321 newtbl->hash_used = 0; 322 specificdata_init(fileassoc_domain, &newtbl->data); 323 324 /* XXX we need to make sure nothing uses fileassoc here! */ 325 326 hh = tbl->hash_tbl; 327 for (i = 0; i < tbl->hash_size; i++) { 328 struct fileassoc_hash_entry *mhe; 329 330 while ((mhe = LIST_FIRST(&hh[i])) != NULL) { 331 struct fileassoc_hashhead *vhh; 332 size_t indx; 333 334 LIST_REMOVE(mhe, entries); 335 336 indx = FILEASSOC_HASH(newtbl, mhe->handle); 337 vhh = &(newtbl->hash_tbl[indx]); 338 339 LIST_INSERT_HEAD(vhh, mhe, entries); 340 341 newtbl->hash_used++; 342 } 343 } 344 345 if (tbl->hash_used != newtbl->hash_used) 346 panic("fileassoc_table_resize: inconsistency detected! " 347 "needed %zu entries, got %zu", tbl->hash_used, 348 newtbl->hash_used); 349 350 hashdone(tbl->hash_tbl, M_TEMP); 351 specificdata_fini(fileassoc_domain, &tbl->data); 352 kmem_free(tbl, sizeof(*tbl)); 353 354 return (newtbl); 355 } 356 357 /* 358 * Create a new fileassoc table. 359 */ 360 static struct fileassoc_table * 361 fileassoc_table_add(struct mount *mp) 362 { 363 struct fileassoc_table *tbl; 364 365 /* Check for existing table for device. */ 366 tbl = fileassoc_table_lookup(mp); 367 if (tbl != NULL) 368 return (tbl); 369 370 /* Allocate and initialize a table. */ 371 tbl = kmem_zalloc(sizeof(*tbl), KM_SLEEP); 372 tbl->hash_size = FILEASSOC_INITIAL_TABLESIZE; 373 tbl->hash_tbl = hashinit(tbl->hash_size, HASH_LIST, M_TEMP, 374 M_WAITOK | M_ZERO, &tbl->hash_mask); 375 tbl->hash_used = 0; 376 specificdata_init(fileassoc_domain, &tbl->data); 377 378 mount_setspecific(mp, fileassoc_mountspecific_key, tbl); 379 380 return (tbl); 381 } 382 383 /* 384 * Delete a table. 385 */ 386 int 387 fileassoc_table_delete(struct mount *mp) 388 { 389 struct fileassoc_table *tbl; 390 391 tbl = fileassoc_table_lookup(mp); 392 if (tbl == NULL) 393 return (EEXIST); 394 395 mount_setspecific(mp, fileassoc_mountspecific_key, NULL); 396 table_dtor(tbl); 397 398 return (0); 399 } 400 401 /* 402 * Run a callback for each hook entry in a table. 403 */ 404 int 405 fileassoc_table_run(struct mount *mp, fileassoc_t assoc, fileassoc_cb_t cb) 406 { 407 struct fileassoc_table *tbl; 408 struct fileassoc_hashhead *hh; 409 u_long i; 410 411 tbl = fileassoc_table_lookup(mp); 412 if (tbl == NULL) 413 return (EEXIST); 414 415 hh = tbl->hash_tbl; 416 for (i = 0; i < tbl->hash_size; i++) { 417 struct fileassoc_hash_entry *mhe; 418 419 LIST_FOREACH(mhe, &hh[i], entries) { 420 void *data; 421 422 data = file_getdata(mhe, assoc); 423 if (data != NULL) 424 cb(data); 425 } 426 } 427 428 return (0); 429 } 430 431 /* 432 * Clear a table for a given hook. 433 */ 434 int 435 fileassoc_table_clear(struct mount *mp, fileassoc_t assoc) 436 { 437 struct fileassoc_table *tbl; 438 struct fileassoc_hashhead *hh; 439 u_long i; 440 441 tbl = fileassoc_table_lookup(mp); 442 if (tbl == NULL) 443 return (EEXIST); 444 445 hh = tbl->hash_tbl; 446 for (i = 0; i < tbl->hash_size; i++) { 447 struct fileassoc_hash_entry *mhe; 448 449 LIST_FOREACH(mhe, &hh[i], entries) { 450 file_cleanup(mhe, assoc); 451 file_setdata(mhe, assoc, NULL); 452 } 453 } 454 455 return (0); 456 } 457 458 /* 459 * Add a file entry to a table. 460 */ 461 static struct fileassoc_hash_entry * 462 fileassoc_file_add(struct vnode *vp, fhandle_t *hint) 463 { 464 struct fileassoc_table *tbl; 465 struct fileassoc_hashhead *vhh; 466 struct fileassoc_hash_entry *e; 467 size_t indx; 468 fhandle_t *th; 469 int error; 470 471 if (hint == NULL) { 472 error = vfs_composefh_alloc(vp, &th); 473 if (error) 474 return (NULL); 475 } else 476 th = hint; 477 478 e = fileassoc_file_lookup(vp, th); 479 if (e != NULL) { 480 if (hint == NULL) 481 vfs_composefh_free(th); 482 483 return (e); 484 } 485 486 tbl = fileassoc_table_lookup(vp->v_mount); 487 if (tbl == NULL) { 488 tbl = fileassoc_table_add(vp->v_mount); 489 } 490 491 indx = FILEASSOC_HASH(tbl, th); 492 vhh = &(tbl->hash_tbl[indx]); 493 494 e = kmem_zalloc(sizeof(*e), KM_SLEEP); 495 e->handle = th; 496 specificdata_init(fileassoc_domain, &e->data); 497 LIST_INSERT_HEAD(vhh, e, entries); 498 499 /* 500 * This decides when we need to resize the table. For now, 501 * resize it whenever we "filled" up the number of slots it 502 * has. That's not really true unless of course we had zero 503 * collisions. Think positive! :) 504 */ 505 if (++(tbl->hash_used) == tbl->hash_size) { 506 struct fileassoc_table *newtbl; 507 508 newtbl = fileassoc_table_resize(tbl); 509 mount_setspecific(vp->v_mount, fileassoc_mountspecific_key, 510 newtbl); 511 } 512 513 return (e); 514 } 515 516 /* 517 * Delete a file entry from a table. 518 */ 519 int 520 fileassoc_file_delete(struct vnode *vp) 521 { 522 struct fileassoc_table *tbl; 523 struct fileassoc_hash_entry *mhe; 524 525 mhe = fileassoc_file_lookup(vp, NULL); 526 if (mhe == NULL) 527 return (ENOENT); 528 529 file_free(mhe); 530 531 tbl = fileassoc_table_lookup(vp->v_mount); 532 --(tbl->hash_used); /* XXX gc? */ 533 534 return (0); 535 } 536 537 /* 538 * Add a hook to a vnode. 539 */ 540 int 541 fileassoc_add(struct vnode *vp, fileassoc_t assoc, void *data) 542 { 543 struct fileassoc_hash_entry *e; 544 void *olddata; 545 546 e = fileassoc_file_lookup(vp, NULL); 547 if (e == NULL) { 548 e = fileassoc_file_add(vp, NULL); 549 if (e == NULL) 550 return (ENOTDIR); 551 } 552 553 olddata = file_getdata(e, assoc); 554 if (olddata != NULL) 555 return (EEXIST); 556 557 file_setdata(e, assoc, data); 558 559 e->nassocs++; 560 561 return (0); 562 } 563 564 /* 565 * Clear a hook from a vnode. 566 */ 567 int 568 fileassoc_clear(struct vnode *vp, fileassoc_t assoc) 569 { 570 struct fileassoc_hash_entry *mhe; 571 572 mhe = fileassoc_file_lookup(vp, NULL); 573 if (mhe == NULL) 574 return (ENOENT); 575 576 file_cleanup(mhe, assoc); 577 file_setdata(mhe, assoc, NULL); 578 579 --(mhe->nassocs); /* XXX gc? */ 580 581 return (0); 582 } 583
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