1/* FS-Cache object state machine handler 2 * 3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * See Documentation/filesystems/caching/object.txt for a description of the 12 * object state machine and the in-kernel representations. 13 */ 14 15#define FSCACHE_DEBUG_LEVEL COOKIE 16#include <linux/module.h> 17#include "internal.h" 18 19const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = { 20 [FSCACHE_OBJECT_INIT] = "OBJECT_INIT", 21 [FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP", 22 [FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING", 23 [FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE", 24 [FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE", 25 [FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING", 26 [FSCACHE_OBJECT_DYING] = "OBJECT_DYING", 27 [FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING", 28 [FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT", 29 [FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING", 30 [FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING", 31 [FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING", 32 [FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD", 33}; 34EXPORT_SYMBOL(fscache_object_states); 35 36const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = { 37 [FSCACHE_OBJECT_INIT] = "INIT", 38 [FSCACHE_OBJECT_LOOKING_UP] = "LOOK", 39 [FSCACHE_OBJECT_CREATING] = "CRTN", 40 [FSCACHE_OBJECT_AVAILABLE] = "AVBL", 41 [FSCACHE_OBJECT_ACTIVE] = "ACTV", 42 [FSCACHE_OBJECT_UPDATING] = "UPDT", 43 [FSCACHE_OBJECT_DYING] = "DYNG", 44 [FSCACHE_OBJECT_LC_DYING] = "LCDY", 45 [FSCACHE_OBJECT_ABORT_INIT] = "ABTI", 46 [FSCACHE_OBJECT_RELEASING] = "RELS", 47 [FSCACHE_OBJECT_RECYCLING] = "RCYC", 48 [FSCACHE_OBJECT_WITHDRAWING] = "WTHD", 49 [FSCACHE_OBJECT_DEAD] = "DEAD", 50}; 51 52static int fscache_get_object(struct fscache_object *); 53static void fscache_put_object(struct fscache_object *); 54static void fscache_initialise_object(struct fscache_object *); 55static void fscache_lookup_object(struct fscache_object *); 56static void fscache_object_available(struct fscache_object *); 57static void fscache_release_object(struct fscache_object *); 58static void fscache_withdraw_object(struct fscache_object *); 59static void fscache_enqueue_dependents(struct fscache_object *); 60static void fscache_dequeue_object(struct fscache_object *); 61 62/* 63 * we need to notify the parent when an op completes that we had outstanding 64 * upon it 65 */ 66static inline void fscache_done_parent_op(struct fscache_object *object) 67{ 68 struct fscache_object *parent = object->parent; 69 70 _enter("OBJ%x {OBJ%x,%x}", 71 object->debug_id, parent->debug_id, parent->n_ops); 72 73 spin_lock_nested(&parent->lock, 1); 74 parent->n_ops--; 75 parent->n_obj_ops--; 76 if (parent->n_ops == 0) 77 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); 78 spin_unlock(&parent->lock); 79} 80 81/* 82 * process events that have been sent to an object's state machine 83 * - initiates parent lookup 84 * - does object lookup 85 * - does object creation 86 * - does object recycling and retirement 87 * - does object withdrawal 88 */ 89static void fscache_object_state_machine(struct fscache_object *object) 90{ 91 enum fscache_object_state new_state; 92 struct fscache_cookie *cookie; 93 94 ASSERT(object != NULL); 95 96 _enter("{OBJ%x,%s,%lx}", 97 object->debug_id, fscache_object_states[object->state], 98 object->events); 99 100 switch (object->state) { 101 /* wait for the parent object to become ready */ 102 case FSCACHE_OBJECT_INIT: 103 object->event_mask = 104 ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED); 105 fscache_initialise_object(object); 106 goto done; 107 108 /* look up the object metadata on disk */ 109 case FSCACHE_OBJECT_LOOKING_UP: 110 fscache_lookup_object(object); 111 goto lookup_transit; 112 113 /* create the object metadata on disk */ 114 case FSCACHE_OBJECT_CREATING: 115 fscache_lookup_object(object); 116 goto lookup_transit; 117 118 /* handle an object becoming available; start pending 119 * operations and queue dependent operations for processing */ 120 case FSCACHE_OBJECT_AVAILABLE: 121 fscache_object_available(object); 122 goto active_transit; 123 124 /* normal running state */ 125 case FSCACHE_OBJECT_ACTIVE: 126 goto active_transit; 127 128 /* update the object metadata on disk */ 129 case FSCACHE_OBJECT_UPDATING: 130 clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events); 131 fscache_stat(&fscache_n_updates_run); 132 fscache_stat(&fscache_n_cop_update_object); 133 object->cache->ops->update_object(object); 134 fscache_stat_d(&fscache_n_cop_update_object); 135 goto active_transit; 136 137 /* handle an object dying during lookup or creation */ 138 case FSCACHE_OBJECT_LC_DYING: 139 object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE); 140 fscache_stat(&fscache_n_cop_lookup_complete); 141 object->cache->ops->lookup_complete(object); 142 fscache_stat_d(&fscache_n_cop_lookup_complete); 143 144 spin_lock(&object->lock); 145 object->state = FSCACHE_OBJECT_DYING; 146 cookie = object->cookie; 147 if (cookie) { 148 if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, 149 &cookie->flags)) 150 wake_up_bit(&cookie->flags, 151 FSCACHE_COOKIE_LOOKING_UP); 152 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, 153 &cookie->flags)) 154 wake_up_bit(&cookie->flags, 155 FSCACHE_COOKIE_CREATING); 156 } 157 spin_unlock(&object->lock); 158 159 fscache_done_parent_op(object); 160 161 /* wait for completion of all active operations on this object 162 * and the death of all child objects of this object */ 163 case FSCACHE_OBJECT_DYING: 164 dying: 165 clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events); 166 spin_lock(&object->lock); 167 _debug("dying OBJ%x {%d,%d}", 168 object->debug_id, object->n_ops, object->n_children); 169 if (object->n_ops == 0 && object->n_children == 0) { 170 object->event_mask &= 171 ~(1 << FSCACHE_OBJECT_EV_CLEARED); 172 object->event_mask |= 173 (1 << FSCACHE_OBJECT_EV_WITHDRAW) | 174 (1 << FSCACHE_OBJECT_EV_RETIRE) | 175 (1 << FSCACHE_OBJECT_EV_RELEASE) | 176 (1 << FSCACHE_OBJECT_EV_ERROR); 177 } else { 178 object->event_mask &= 179 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | 180 (1 << FSCACHE_OBJECT_EV_RETIRE) | 181 (1 << FSCACHE_OBJECT_EV_RELEASE) | 182 (1 << FSCACHE_OBJECT_EV_ERROR)); 183 object->event_mask |= 184 1 << FSCACHE_OBJECT_EV_CLEARED; 185 } 186 spin_unlock(&object->lock); 187 fscache_enqueue_dependents(object); 188 fscache_start_operations(object); 189 goto terminal_transit; 190 191 /* handle an abort during initialisation */ 192 case FSCACHE_OBJECT_ABORT_INIT: 193 _debug("handle abort init %lx", object->events); 194 object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE); 195 196 spin_lock(&object->lock); 197 fscache_dequeue_object(object); 198 199 object->state = FSCACHE_OBJECT_DYING; 200 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, 201 &object->cookie->flags)) 202 wake_up_bit(&object->cookie->flags, 203 FSCACHE_COOKIE_CREATING); 204 spin_unlock(&object->lock); 205 goto dying; 206 207 /* handle the netfs releasing an object and possibly marking it 208 * obsolete too */ 209 case FSCACHE_OBJECT_RELEASING: 210 case FSCACHE_OBJECT_RECYCLING: 211 object->event_mask &= 212 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | 213 (1 << FSCACHE_OBJECT_EV_RETIRE) | 214 (1 << FSCACHE_OBJECT_EV_RELEASE) | 215 (1 << FSCACHE_OBJECT_EV_ERROR)); 216 fscache_release_object(object); 217 spin_lock(&object->lock); 218 object->state = FSCACHE_OBJECT_DEAD; 219 spin_unlock(&object->lock); 220 fscache_stat(&fscache_n_object_dead); 221 goto terminal_transit; 222 223 /* handle the parent cache of this object being withdrawn from 224 * active service */ 225 case FSCACHE_OBJECT_WITHDRAWING: 226 object->event_mask &= 227 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | 228 (1 << FSCACHE_OBJECT_EV_RETIRE) | 229 (1 << FSCACHE_OBJECT_EV_RELEASE) | 230 (1 << FSCACHE_OBJECT_EV_ERROR)); 231 fscache_withdraw_object(object); 232 spin_lock(&object->lock); 233 object->state = FSCACHE_OBJECT_DEAD; 234 spin_unlock(&object->lock); 235 fscache_stat(&fscache_n_object_dead); 236 goto terminal_transit; 237 238 /* complain about the object being woken up once it is 239 * deceased */ 240 case FSCACHE_OBJECT_DEAD: 241 printk(KERN_ERR "FS-Cache:" 242 " Unexpected event in dead state %lx\n", 243 object->events & object->event_mask); 244 BUG(); 245 246 default: 247 printk(KERN_ERR "FS-Cache: Unknown object state %u\n", 248 object->state); 249 BUG(); 250 } 251 252 /* determine the transition from a lookup state */ 253lookup_transit: 254 switch (fls(object->events & object->event_mask) - 1) { 255 case FSCACHE_OBJECT_EV_WITHDRAW: 256 case FSCACHE_OBJECT_EV_RETIRE: 257 case FSCACHE_OBJECT_EV_RELEASE: 258 case FSCACHE_OBJECT_EV_ERROR: 259 new_state = FSCACHE_OBJECT_LC_DYING; 260 goto change_state; 261 case FSCACHE_OBJECT_EV_REQUEUE: 262 goto done; 263 case -1: 264 goto done; /* sleep until event */ 265 default: 266 goto unsupported_event; 267 } 268 269 /* determine the transition from an active state */ 270active_transit: 271 switch (fls(object->events & object->event_mask) - 1) { 272 case FSCACHE_OBJECT_EV_WITHDRAW: 273 case FSCACHE_OBJECT_EV_RETIRE: 274 case FSCACHE_OBJECT_EV_RELEASE: 275 case FSCACHE_OBJECT_EV_ERROR: 276 new_state = FSCACHE_OBJECT_DYING; 277 goto change_state; 278 case FSCACHE_OBJECT_EV_UPDATE: 279 new_state = FSCACHE_OBJECT_UPDATING; 280 goto change_state; 281 case -1: 282 new_state = FSCACHE_OBJECT_ACTIVE; 283 goto change_state; /* sleep until event */ 284 default: 285 goto unsupported_event; 286 } 287 288 /* determine the transition from a terminal state */ 289terminal_transit: 290 switch (fls(object->events & object->event_mask) - 1) { 291 case FSCACHE_OBJECT_EV_WITHDRAW: 292 new_state = FSCACHE_OBJECT_WITHDRAWING; 293 goto change_state; 294 case FSCACHE_OBJECT_EV_RETIRE: 295 new_state = FSCACHE_OBJECT_RECYCLING; 296 goto change_state; 297 case FSCACHE_OBJECT_EV_RELEASE: 298 new_state = FSCACHE_OBJECT_RELEASING; 299 goto change_state; 300 case FSCACHE_OBJECT_EV_ERROR: 301 new_state = FSCACHE_OBJECT_WITHDRAWING; 302 goto change_state; 303 case FSCACHE_OBJECT_EV_CLEARED: 304 new_state = FSCACHE_OBJECT_DYING; 305 goto change_state; 306 case -1: 307 goto done; /* sleep until event */ 308 default: 309 goto unsupported_event; 310 } 311 312change_state: 313 spin_lock(&object->lock); 314 object->state = new_state; 315 spin_unlock(&object->lock); 316 317done: 318 _leave(" [->%s]", fscache_object_states[object->state]); 319 return; 320 321unsupported_event: 322 printk(KERN_ERR "FS-Cache:" 323 " Unsupported event %lx [mask %lx] in state %s\n", 324 object->events, object->event_mask, 325 fscache_object_states[object->state]); 326 BUG(); 327} 328 329/* 330 * execute an object 331 */ 332void fscache_object_work_func(struct work_struct *work) 333{ 334 struct fscache_object *object = 335 container_of(work, struct fscache_object, work); 336 unsigned long start; 337 338 _enter("{OBJ%x}", object->debug_id); 339 340 start = jiffies; 341 fscache_object_state_machine(object); 342 fscache_hist(fscache_objs_histogram, start); 343 if (object->events & object->event_mask) 344 fscache_enqueue_object(object); 345 clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); 346 fscache_put_object(object); 347} 348EXPORT_SYMBOL(fscache_object_work_func); 349 350/* 351 * initialise an object 352 * - check the specified object's parent to see if we can make use of it 353 * immediately to do a creation 354 * - we may need to start the process of creating a parent and we need to wait 355 * for the parent's lookup and creation to complete if it's not there yet 356 * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the 357 * leaf-most cookies of the object and all its children 358 */ 359static void fscache_initialise_object(struct fscache_object *object) 360{ 361 struct fscache_object *parent; 362 363 _enter(""); 364 ASSERT(object->cookie != NULL); 365 ASSERT(object->cookie->parent != NULL); 366 367 if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) | 368 (1 << FSCACHE_OBJECT_EV_RELEASE) | 369 (1 << FSCACHE_OBJECT_EV_RETIRE) | 370 (1 << FSCACHE_OBJECT_EV_WITHDRAW))) { 371 _debug("abort init %lx", object->events); 372 spin_lock(&object->lock); 373 object->state = FSCACHE_OBJECT_ABORT_INIT; 374 spin_unlock(&object->lock); 375 return; 376 } 377 378 spin_lock(&object->cookie->lock); 379 spin_lock_nested(&object->cookie->parent->lock, 1); 380 381 parent = object->parent; 382 if (!parent) { 383 _debug("no parent"); 384 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); 385 } else { 386 spin_lock(&object->lock); 387 spin_lock_nested(&parent->lock, 1); 388 _debug("parent %s", fscache_object_states[parent->state]); 389 390 if (parent->state >= FSCACHE_OBJECT_DYING) { 391 _debug("bad parent"); 392 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); 393 } else if (parent->state < FSCACHE_OBJECT_AVAILABLE) { 394 _debug("wait"); 395 396 /* we may get woken up in this state by child objects 397 * binding on to us, so we need to make sure we don't 398 * add ourself to the list multiple times */ 399 if (list_empty(&object->dep_link)) { 400 fscache_stat(&fscache_n_cop_grab_object); 401 object->cache->ops->grab_object(object); 402 fscache_stat_d(&fscache_n_cop_grab_object); 403 list_add(&object->dep_link, 404 &parent->dependents); 405 406 /* fscache_acquire_non_index_cookie() uses this 407 * to wake the chain up */ 408 if (parent->state == FSCACHE_OBJECT_INIT) 409 fscache_enqueue_object(parent); 410 } 411 } else { 412 _debug("go"); 413 parent->n_ops++; 414 parent->n_obj_ops++; 415 object->lookup_jif = jiffies; 416 object->state = FSCACHE_OBJECT_LOOKING_UP; 417 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); 418 } 419 420 spin_unlock(&parent->lock); 421 spin_unlock(&object->lock); 422 } 423 424 spin_unlock(&object->cookie->parent->lock); 425 spin_unlock(&object->cookie->lock); 426 _leave(""); 427} 428 429/* 430 * look an object up in the cache from which it was allocated 431 * - we hold an "access lock" on the parent object, so the parent object cannot 432 * be withdrawn by either party till we've finished 433 * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the 434 * leaf-most cookies of the object and all its children 435 */ 436static void fscache_lookup_object(struct fscache_object *object) 437{ 438 struct fscache_cookie *cookie = object->cookie; 439 struct fscache_object *parent; 440 int ret; 441 442 _enter(""); 443 444 parent = object->parent; 445 ASSERT(parent != NULL); 446 ASSERTCMP(parent->n_ops, >, 0); 447 ASSERTCMP(parent->n_obj_ops, >, 0); 448 449 /* make sure the parent is still available */ 450 ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE); 451 452 if (parent->state >= FSCACHE_OBJECT_DYING || 453 test_bit(FSCACHE_IOERROR, &object->cache->flags)) { 454 _debug("unavailable"); 455 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); 456 _leave(""); 457 return; 458 } 459 460 _debug("LOOKUP \"%s/%s\" in \"%s\"", 461 parent->cookie->def->name, cookie->def->name, 462 object->cache->tag->name); 463 464 fscache_stat(&fscache_n_object_lookups); 465 fscache_stat(&fscache_n_cop_lookup_object); 466 ret = object->cache->ops->lookup_object(object); 467 fscache_stat_d(&fscache_n_cop_lookup_object); 468 469 if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events)) 470 set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); 471 472 if (ret == -ETIMEDOUT) { 473 /* probably stuck behind another object, so move this one to 474 * the back of the queue */ 475 fscache_stat(&fscache_n_object_lookups_timed_out); 476 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); 477 } 478 479 _leave(""); 480} 481 482/** 483 * fscache_object_lookup_negative - Note negative cookie lookup 484 * @object: Object pointing to cookie to mark 485 * 486 * Note negative lookup, permitting those waiting to read data from an already 487 * existing backing object to continue as there's no data for them to read. 488 */ 489void fscache_object_lookup_negative(struct fscache_object *object) 490{ 491 struct fscache_cookie *cookie = object->cookie; 492 493 _enter("{OBJ%x,%s}", 494 object->debug_id, fscache_object_states[object->state]); 495 496 spin_lock(&object->lock); 497 if (object->state == FSCACHE_OBJECT_LOOKING_UP) { 498 fscache_stat(&fscache_n_object_lookups_negative); 499 500 /* transit here to allow write requests to begin stacking up 501 * and read requests to begin returning ENODATA */ 502 object->state = FSCACHE_OBJECT_CREATING; 503 spin_unlock(&object->lock); 504 505 set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags); 506 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); 507 508 _debug("wake up lookup %p", &cookie->flags); 509 smp_mb__before_clear_bit(); 510 clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); 511 smp_mb__after_clear_bit(); 512 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); 513 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); 514 } else { 515 ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING); 516 spin_unlock(&object->lock); 517 } 518 519 _leave(""); 520} 521EXPORT_SYMBOL(fscache_object_lookup_negative); 522 523/** 524 * fscache_obtained_object - Note successful object lookup or creation 525 * @object: Object pointing to cookie to mark 526 * 527 * Note successful lookup and/or creation, permitting those waiting to write 528 * data to a backing object to continue. 529 * 530 * Note that after calling this, an object's cookie may be relinquished by the 531 * netfs, and so must be accessed with object lock held. 532 */ 533void fscache_obtained_object(struct fscache_object *object) 534{ 535 struct fscache_cookie *cookie = object->cookie; 536 537 _enter("{OBJ%x,%s}", 538 object->debug_id, fscache_object_states[object->state]); 539 540 /* if we were still looking up, then we must have a positive lookup 541 * result, in which case there may be data available */ 542 spin_lock(&object->lock); 543 if (object->state == FSCACHE_OBJECT_LOOKING_UP) { 544 fscache_stat(&fscache_n_object_lookups_positive); 545 546 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); 547 548 object->state = FSCACHE_OBJECT_AVAILABLE; 549 spin_unlock(&object->lock); 550 551 smp_mb__before_clear_bit(); 552 clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); 553 smp_mb__after_clear_bit(); 554 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); 555 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); 556 } else { 557 ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING); 558 fscache_stat(&fscache_n_object_created); 559 560 object->state = FSCACHE_OBJECT_AVAILABLE; 561 spin_unlock(&object->lock); 562 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); 563 smp_wmb(); 564 } 565 566 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags)) 567 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING); 568 569 _leave(""); 570} 571EXPORT_SYMBOL(fscache_obtained_object); 572 573/* 574 * handle an object that has just become available 575 */ 576static void fscache_object_available(struct fscache_object *object) 577{ 578 _enter("{OBJ%x}", object->debug_id); 579 580 spin_lock(&object->lock); 581 582 if (object->cookie && 583 test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags)) 584 wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING); 585 586 fscache_done_parent_op(object); 587 if (object->n_in_progress == 0) { 588 if (object->n_ops > 0) { 589 ASSERTCMP(object->n_ops, >=, object->n_obj_ops); 590 ASSERTIF(object->n_ops > object->n_obj_ops, 591 !list_empty(&object->pending_ops)); 592 fscache_start_operations(object); 593 } else { 594 ASSERT(list_empty(&object->pending_ops)); 595 } 596 } 597 spin_unlock(&object->lock); 598 599 fscache_stat(&fscache_n_cop_lookup_complete); 600 object->cache->ops->lookup_complete(object); 601 fscache_stat_d(&fscache_n_cop_lookup_complete); 602 fscache_enqueue_dependents(object); 603 604 fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif); 605 fscache_stat(&fscache_n_object_avail); 606 607 _leave(""); 608} 609 610/* 611 * drop an object's attachments 612 */ 613static void fscache_drop_object(struct fscache_object *object) 614{ 615 struct fscache_object *parent = object->parent; 616 struct fscache_cache *cache = object->cache; 617 618 _enter("{OBJ%x,%d}", object->debug_id, object->n_children); 619 620 ASSERTCMP(object->cookie, ==, NULL); 621 ASSERT(hlist_unhashed(&object->cookie_link)); 622 623 spin_lock(&cache->object_list_lock); 624 list_del_init(&object->cache_link); 625 spin_unlock(&cache->object_list_lock); 626 627 fscache_stat(&fscache_n_cop_drop_object); 628 cache->ops->drop_object(object); 629 fscache_stat_d(&fscache_n_cop_drop_object); 630 631 if (parent) { 632 _debug("release parent OBJ%x {%d}", 633 parent->debug_id, parent->n_children); 634 635 spin_lock(&parent->lock); 636 parent->n_children--; 637 if (parent->n_children == 0) 638 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); 639 spin_unlock(&parent->lock); 640 object->parent = NULL; 641 } 642 643 /* this just shifts the object release to the work processor */ 644 fscache_put_object(object); 645 646 _leave(""); 647} 648 649/* 650 * release or recycle an object that the netfs has discarded 651 */ 652static void fscache_release_object(struct fscache_object *object) 653{ 654 _enter(""); 655 656 fscache_drop_object(object); 657} 658 659/* 660 * withdraw an object from active service 661 */ 662static void fscache_withdraw_object(struct fscache_object *object) 663{ 664 struct fscache_cookie *cookie; 665 bool detached; 666 667 _enter(""); 668 669 spin_lock(&object->lock); 670 cookie = object->cookie; 671 if (cookie) { 672 /* need to get the cookie lock before the object lock, starting 673 * from the object pointer */ 674 atomic_inc(&cookie->usage); 675 spin_unlock(&object->lock); 676 677 detached = false; 678 spin_lock(&cookie->lock); 679 spin_lock(&object->lock); 680 681 if (object->cookie == cookie) { 682 hlist_del_init(&object->cookie_link); 683 object->cookie = NULL; 684 detached = true; 685 } 686 spin_unlock(&cookie->lock); 687 fscache_cookie_put(cookie); 688 if (detached) 689 fscache_cookie_put(cookie); 690 } 691 692 spin_unlock(&object->lock); 693 694 fscache_drop_object(object); 695} 696 697/* 698 * withdraw an object from active service at the behest of the cache 699 * - need break the links to a cached object cookie 700 * - called under two situations: 701 * (1) recycler decides to reclaim an in-use object 702 * (2) a cache is unmounted 703 * - have to take care as the cookie can be being relinquished by the netfs 704 * simultaneously 705 * - the object is pinned by the caller holding a refcount on it 706 */ 707void fscache_withdrawing_object(struct fscache_cache *cache, 708 struct fscache_object *object) 709{ 710 bool enqueue = false; 711 712 _enter(",OBJ%x", object->debug_id); 713 714 spin_lock(&object->lock); 715 if (object->state < FSCACHE_OBJECT_WITHDRAWING) { 716 object->state = FSCACHE_OBJECT_WITHDRAWING; 717 enqueue = true; 718 } 719 spin_unlock(&object->lock); 720 721 if (enqueue) 722 fscache_enqueue_object(object); 723 724 _leave(""); 725} 726 727/* 728 * get a ref on an object 729 */ 730static int fscache_get_object(struct fscache_object *object) 731{ 732 int ret; 733 734 fscache_stat(&fscache_n_cop_grab_object); 735 ret = object->cache->ops->grab_object(object) ? 0 : -EAGAIN; 736 fscache_stat_d(&fscache_n_cop_grab_object); 737 return ret; 738} 739 740/* 741 * discard a ref on a work item 742 */ 743static void fscache_put_object(struct fscache_object *object) 744{ 745 fscache_stat(&fscache_n_cop_put_object); 746 object->cache->ops->put_object(object); 747 fscache_stat_d(&fscache_n_cop_put_object); 748} 749 750/* 751 * enqueue an object for metadata-type processing 752 */ 753void fscache_enqueue_object(struct fscache_object *object) 754{ 755 _enter("{OBJ%x}", object->debug_id); 756 757 if (fscache_get_object(object) >= 0) { 758 wait_queue_head_t *cong_wq = 759 &get_cpu_var(fscache_object_cong_wait); 760 761 if (queue_work(fscache_object_wq, &object->work)) { 762 if (fscache_object_congested()) 763 wake_up(cong_wq); 764 } else 765 fscache_put_object(object); 766 767 put_cpu_var(fscache_object_cong_wait); 768 } 769} 770 771/** 772 * fscache_object_sleep_till_congested - Sleep until object wq is congested 773 * @timoutp: Scheduler sleep timeout 774 * 775 * Allow an object handler to sleep until the object workqueue is congested. 776 * 777 * The caller must set up a wake up event before calling this and must have set 778 * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own 779 * condition before calling this function as no test is made here. 780 * 781 * %true is returned if the object wq is congested, %false otherwise. 782 */ 783bool fscache_object_sleep_till_congested(signed long *timeoutp) 784{ 785 wait_queue_head_t *cong_wq = &__get_cpu_var(fscache_object_cong_wait); 786 DEFINE_WAIT(wait); 787 788 if (fscache_object_congested()) 789 return true; 790 791 add_wait_queue_exclusive(cong_wq, &wait); 792 if (!fscache_object_congested()) 793 *timeoutp = schedule_timeout(*timeoutp); 794 finish_wait(cong_wq, &wait); 795 796 return fscache_object_congested(); 797} 798EXPORT_SYMBOL_GPL(fscache_object_sleep_till_congested); 799 800/* 801 * enqueue the dependents of an object for metadata-type processing 802 * - the caller must hold the object's lock 803 * - this may cause an already locked object to wind up being processed again 804 */ 805static void fscache_enqueue_dependents(struct fscache_object *object) 806{ 807 struct fscache_object *dep; 808 809 _enter("{OBJ%x}", object->debug_id); 810 811 if (list_empty(&object->dependents)) 812 return; 813 814 spin_lock(&object->lock); 815 816 while (!list_empty(&object->dependents)) { 817 dep = list_entry(object->dependents.next, 818 struct fscache_object, dep_link); 819 list_del_init(&dep->dep_link); 820 821 822 /* sort onto appropriate lists */ 823 fscache_enqueue_object(dep); 824 fscache_put_object(dep); 825 826 if (!list_empty(&object->dependents)) 827 cond_resched_lock(&object->lock); 828 } 829 830 spin_unlock(&object->lock); 831} 832 833/* 834 * remove an object from whatever queue it's waiting on 835 * - the caller must hold object->lock 836 */ 837void fscache_dequeue_object(struct fscache_object *object) 838{ 839 _enter("{OBJ%x}", object->debug_id); 840 841 if (!list_empty(&object->dep_link)) { 842 spin_lock(&object->parent->lock); 843 list_del_init(&object->dep_link); 844 spin_unlock(&object->parent->lock); 845 } 846 847 _leave(""); 848} 849 850/** 851 * fscache_check_aux - Ask the netfs whether an object on disk is still valid 852 * @object: The object to ask about 853 * @data: The auxiliary data for the object 854 * @datalen: The size of the auxiliary data 855 * 856 * This function consults the netfs about the coherency state of an object 857 */ 858enum fscache_checkaux fscache_check_aux(struct fscache_object *object, 859 const void *data, uint16_t datalen) 860{ 861 enum fscache_checkaux result; 862 863 if (!object->cookie->def->check_aux) { 864 fscache_stat(&fscache_n_checkaux_none); 865 return FSCACHE_CHECKAUX_OKAY; 866 } 867 868 result = object->cookie->def->check_aux(object->cookie->netfs_data, 869 data, datalen); 870 switch (result) { 871 /* entry okay as is */ 872 case FSCACHE_CHECKAUX_OKAY: 873 fscache_stat(&fscache_n_checkaux_okay); 874 break; 875 876 /* entry requires update */ 877 case FSCACHE_CHECKAUX_NEEDS_UPDATE: 878 fscache_stat(&fscache_n_checkaux_update); 879 break; 880 881 /* entry requires deletion */ 882 case FSCACHE_CHECKAUX_OBSOLETE: 883 fscache_stat(&fscache_n_checkaux_obsolete); 884 break; 885 886 default: 887 BUG(); 888 } 889 890 return result; 891} 892EXPORT_SYMBOL(fscache_check_aux); 893