fs/cachefiles/ondemand.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #include <linux/anon_inodes.h>
   3 #include <linux/uio.h>
   4 #include "internal.h"
   5
   6 struct ondemand_anon_file {
   7         struct file *file;
   8         int fd;
   9 };
  10
  11 static inline void cachefiles_req_put(struct cachefiles_req *req)
  12 {
  13         if (refcount_dec_and_test(&req->ref))
  14                 kfree(req);
  15 }
  16
  17 static int cachefiles_ondemand_fd_release(struct inode *inode,
  18                                           struct file *file)
  19 {
  20         struct cachefiles_object *object = file->private_data;
  21         struct cachefiles_cache *cache;
  22         struct cachefiles_ondemand_info *info;
  23         int object_id;
  24         struct cachefiles_req *req;
  25         XA_STATE(xas, NULL, 0);
  26
  27         if (!object)
  28                 return 0;
  29
  30         info = object->ondemand;
  31         cache = object->volume->cache;
  32         xas.xa = &cache->reqs;
  33
  34         xa_lock(&cache->reqs);
  35         spin_lock(&info->lock);
  36         object_id = info->ondemand_id;
  37         info->ondemand_id = CACHEFILES_ONDEMAND_ID_CLOSED;
  38         cachefiles_ondemand_set_object_close(object);
  39         spin_unlock(&info->lock);
  40
  41         /* Only flush CACHEFILES_REQ_NEW marked req to avoid race with daemon_read */
  42         xas_for_each_marked(&xas, req, ULONG_MAX, CACHEFILES_REQ_NEW) {
  43                 if (req->msg.object_id == object_id &&
  44                     req->msg.opcode == CACHEFILES_OP_CLOSE) {
  45                         complete(&req->done);
  46                         xas_store(&xas, NULL);
  47                 }
  48         }
  49         xa_unlock(&cache->reqs);
  50
  51         xa_erase(&cache->ondemand_ids, object_id);
  52         trace_cachefiles_ondemand_fd_release(object, object_id);
  53         cachefiles_put_object(object, cachefiles_obj_put_ondemand_fd);
  54         cachefiles_put_unbind_pincount(cache);
  55         return 0;
  56 }
  57
  58 static ssize_t cachefiles_ondemand_fd_write_iter(struct kiocb *kiocb,
  59                                                  struct iov_iter *iter)
  60 {
  61         struct cachefiles_object *object = kiocb->ki_filp->private_data;
  62         struct cachefiles_cache *cache = object->volume->cache;
  63         struct file *file;
  64         size_t len = iter->count, aligned_len = len;
  65         loff_t pos = kiocb->ki_pos;
  66         const struct cred *saved_cred;
  67         int ret;
  68
  69         spin_lock(&object->lock);
  70         file = object->file;
  71         if (!file) {
  72                 spin_unlock(&object->lock);
  73                 return -ENOBUFS;
  74         }
  75         get_file(file);
  76         spin_unlock(&object->lock);
  77
  78         cachefiles_begin_secure(cache, &saved_cred);
  79         ret = __cachefiles_prepare_write(object, file, &pos, &aligned_len, len, true);
  80         cachefiles_end_secure(cache, saved_cred);
  81         if (ret < 0)
  82                 goto out;
  83
  84         trace_cachefiles_ondemand_fd_write(object, file_inode(file), pos, len);
  85         ret = __cachefiles_write(object, file, pos, iter, NULL, NULL);
  86         if (!ret) {
  87                 ret = len;
  88                 kiocb->ki_pos += ret;
  89         }
  90
  91 out:
  92         fput(file);
  93         return ret;
  94 }
  95
  96 static loff_t cachefiles_ondemand_fd_llseek(struct file *filp, loff_t pos,
  97                                             int whence)
  98 {
  99         struct cachefiles_object *object = filp->private_data;
 100         struct file *file;
 101         loff_t ret;
 102
 103         spin_lock(&object->lock);
 104         file = object->file;
 105         if (!file) {
 106                 spin_unlock(&object->lock);
 107                 return -ENOBUFS;
 108         }
 109         get_file(file);
 110         spin_unlock(&object->lock);
 111
 112         ret = vfs_llseek(file, pos, whence);
 113         fput(file);
 114
 115         return ret;
 116 }
 117
 118 static long cachefiles_ondemand_fd_ioctl(struct file *filp, unsigned int ioctl,
 119                                          unsigned long id)
 120 {
 121         struct cachefiles_object *object = filp->private_data;
 122         struct cachefiles_cache *cache = object->volume->cache;
 123         struct cachefiles_req *req;
 124         XA_STATE(xas, &cache->reqs, id);
 125
 126         if (ioctl != CACHEFILES_IOC_READ_COMPLETE)
 127                 return -EINVAL;
 128
 129         if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
 130                 return -EOPNOTSUPP;
 131
 132         xa_lock(&cache->reqs);
 133         req = xas_load(&xas);
 134         if (!req || req->msg.opcode != CACHEFILES_OP_READ ||
 135             req->object != object) {
 136                 xa_unlock(&cache->reqs);
 137                 return -EINVAL;
 138         }
 139         xas_store(&xas, NULL);
 140         xa_unlock(&cache->reqs);
 141
 142         trace_cachefiles_ondemand_cread(object, id);
 143         complete(&req->done);
 144         return 0;
 145 }
 146
 147 static const struct file_operations cachefiles_ondemand_fd_fops = {
 148         .owner          = THIS_MODULE,
 149         .release        = cachefiles_ondemand_fd_release,
 150         .write_iter     = cachefiles_ondemand_fd_write_iter,
 151         .llseek         = cachefiles_ondemand_fd_llseek,
 152         .unlocked_ioctl = cachefiles_ondemand_fd_ioctl,
 153 };
 154
 155 /*
 156  * OPEN request Completion (copen)
 157  * - command: "copen <id>,<cache_size>"
 158  *   <cache_size> indicates the object size if >=0, error code if negative
 159  */
 160 int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args)
 161 {
 162         struct cachefiles_req *req;
 163         struct fscache_cookie *cookie;
 164         struct cachefiles_ondemand_info *info;
 165         char *pid, *psize;
 166         unsigned long id;
 167         long size;
 168         int ret;
 169         XA_STATE(xas, &cache->reqs, 0);
 170
 171         if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
 172                 return -EOPNOTSUPP;
 173
 174         if (!*args) {
 175                 pr_err("Empty id specified\n");
 176                 return -EINVAL;
 177         }
 178
 179         pid = args;
 180         psize = strchr(args, ',');
 181         if (!psize) {
 182                 pr_err("Cache size is not specified\n");
 183                 return -EINVAL;
 184         }
 185
 186         *psize = 0;
 187         psize++;
 188
 189         ret = kstrtoul(pid, 0, &id);
 190         if (ret)
 191                 return ret;
 192
 193         xa_lock(&cache->reqs);
 194         xas.xa_index = id;
 195         req = xas_load(&xas);
 196         if (!req || req->msg.opcode != CACHEFILES_OP_OPEN ||
 197             !req->object->ondemand->ondemand_id) {
 198                 xa_unlock(&cache->reqs);
 199                 return -EINVAL;
 200         }
 201         xas_store(&xas, NULL);
 202         xa_unlock(&cache->reqs);
 203
 204         info = req->object->ondemand;
 205         /* fail OPEN request if copen format is invalid */
 206         ret = kstrtol(psize, 0, &size);
 207         if (ret) {
 208                 req->error = ret;
 209                 goto out;
 210         }
 211
 212         /* fail OPEN request if daemon reports an error */
 213         if (size < 0) {
 214                 if (!IS_ERR_VALUE(size)) {
 215                         req->error = -EINVAL;
 216                         ret = -EINVAL;
 217                 } else {
 218                         req->error = size;
 219                         ret = 0;
 220                 }
 221                 goto out;
 222         }
 223
 224         spin_lock(&info->lock);
 225         /*
 226          * The anonymous fd was closed before copen ? Fail the request.
 227          *
 228          *             t1             |             t2
 229          * ---------------------------------------------------------
 230          *                             cachefiles_ondemand_copen
 231          *                             req = xa_erase(&cache->reqs, id)
 232          * // Anon fd is maliciously closed.
 233          * cachefiles_ondemand_fd_release
 234          * xa_lock(&cache->reqs)
 235          * cachefiles_ondemand_set_object_close(object)
 236          * xa_unlock(&cache->reqs)
 237          *                             cachefiles_ondemand_set_object_open
 238          *                             // No one will ever close it again.
 239          * cachefiles_ondemand_daemon_read
 240          * cachefiles_ondemand_select_req
 241          *
 242          * Get a read req but its fd is already closed. The daemon can't
 243          * issue a cread ioctl with an closed fd, then hung.
 244          */
 245         if (info->ondemand_id == CACHEFILES_ONDEMAND_ID_CLOSED) {
 246                 spin_unlock(&info->lock);
 247                 req->error = -EBADFD;
 248                 goto out;
 249         }
 250         cookie = req->object->cookie;
 251         cookie->object_size = size;
 252         if (size)
 253                 clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
 254         else
 255                 set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
 256         trace_cachefiles_ondemand_copen(req->object, id, size);
 257
 258         cachefiles_ondemand_set_object_open(req->object);
 259         spin_unlock(&info->lock);
 260         wake_up_all(&cache->daemon_pollwq);
 261
 262 out:
 263         spin_lock(&info->lock);
 264         /* Need to set object close to avoid reopen status continuing */
 265         if (info->ondemand_id == CACHEFILES_ONDEMAND_ID_CLOSED)
 266                 cachefiles_ondemand_set_object_close(req->object);
 267         spin_unlock(&info->lock);
 268         complete(&req->done);
 269         return ret;
 270 }
 271
 272 int cachefiles_ondemand_restore(struct cachefiles_cache *cache, char *args)
 273 {
 274         struct cachefiles_req *req;
 275
 276         XA_STATE(xas, &cache->reqs, 0);
 277
 278         if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
 279                 return -EOPNOTSUPP;
 280
 281         /*
 282          * Reset the requests to CACHEFILES_REQ_NEW state, so that the
 283          * requests have been processed halfway before the crash of the
 284          * user daemon could be reprocessed after the recovery.
 285          */
 286         xas_lock(&xas);
 287         xas_for_each(&xas, req, ULONG_MAX)
 288                 xas_set_mark(&xas, CACHEFILES_REQ_NEW);
 289         xas_unlock(&xas);
 290
 291         wake_up_all(&cache->daemon_pollwq);
 292         return 0;
 293 }
 294
 295 static int cachefiles_ondemand_get_fd(struct cachefiles_req *req,
 296                                       struct ondemand_anon_file *anon_file)
 297 {
 298         struct cachefiles_object *object;
 299         struct cachefiles_cache *cache;
 300         struct cachefiles_open *load;
 301         u32 object_id;
 302         int ret;
 303
 304         object = cachefiles_grab_object(req->object,
 305                         cachefiles_obj_get_ondemand_fd);
 306         cache = object->volume->cache;
 307
 308         ret = xa_alloc_cyclic(&cache->ondemand_ids, &object_id, NULL,
 309                               XA_LIMIT(1, INT_MAX),
 310                               &cache->ondemand_id_next, GFP_KERNEL);
 311         if (ret < 0)
 312                 goto err;
 313
 314         anon_file->fd = get_unused_fd_flags(O_WRONLY);
 315         if (anon_file->fd < 0) {
 316                 ret = anon_file->fd;
 317                 goto err_free_id;
 318         }
 319
 320         anon_file->file = anon_inode_getfile("[cachefiles]",
 321                                 &cachefiles_ondemand_fd_fops, object, O_WRONLY);
 322         if (IS_ERR(anon_file->file)) {
 323                 ret = PTR_ERR(anon_file->file);
 324                 goto err_put_fd;
 325         }
 326
 327         spin_lock(&object->ondemand->lock);
 328         if (object->ondemand->ondemand_id > 0) {
 329                 spin_unlock(&object->ondemand->lock);
 330                 /* Pair with check in cachefiles_ondemand_fd_release(). */
 331                 anon_file->file->private_data = NULL;
 332                 ret = -EEXIST;
 333                 goto err_put_file;
 334         }
 335
 336         anon_file->file->f_mode |= FMODE_PWRITE | FMODE_LSEEK;
 337
 338         load = (void *)req->msg.data;
 339         load->fd = anon_file->fd;
 340         object->ondemand->ondemand_id = object_id;
 341         spin_unlock(&object->ondemand->lock);
 342
 343         cachefiles_get_unbind_pincount(cache);
 344         trace_cachefiles_ondemand_open(object, &req->msg, load);
 345         return 0;
 346
 347 err_put_file:
 348         fput(anon_file->file);
 349         anon_file->file = NULL;
 350 err_put_fd:
 351         put_unused_fd(anon_file->fd);
 352         anon_file->fd = ret;
 353 err_free_id:
 354         xa_erase(&cache->ondemand_ids, object_id);
 355 err:
 356         spin_lock(&object->ondemand->lock);
 357         /* Avoid marking an opened object as closed. */
 358         if (object->ondemand->ondemand_id <= 0)
 359                 cachefiles_ondemand_set_object_close(object);
 360         spin_unlock(&object->ondemand->lock);
 361         cachefiles_put_object(object, cachefiles_obj_put_ondemand_fd);
 362         return ret;
 363 }
 364
 365 static void ondemand_object_worker(struct work_struct *work)
 366 {
 367         struct cachefiles_ondemand_info *info =
 368                 container_of(work, struct cachefiles_ondemand_info, ondemand_work);
 369
 370         cachefiles_ondemand_init_object(info->object);
 371 }
 372
 373 /*
 374  * If there are any inflight or subsequent READ requests on the
 375  * closed object, reopen it.
 376  * Skip read requests whose related object is reopening.
 377  */
 378 static struct cachefiles_req *cachefiles_ondemand_select_req(struct xa_state *xas,
 379                                                               unsigned long xa_max)
 380 {
 381         struct cachefiles_req *req;
 382         struct cachefiles_object *object;
 383         struct cachefiles_ondemand_info *info;
 384
 385         xas_for_each_marked(xas, req, xa_max, CACHEFILES_REQ_NEW) {
 386                 if (req->msg.opcode != CACHEFILES_OP_READ)
 387                         return req;
 388                 object = req->object;
 389                 info = object->ondemand;
 390                 if (cachefiles_ondemand_object_is_close(object)) {
 391                         cachefiles_ondemand_set_object_reopening(object);
 392                         queue_work(fscache_wq, &info->ondemand_work);
 393                         continue;
 394                 }
 395                 if (cachefiles_ondemand_object_is_reopening(object))
 396                         continue;
 397                 return req;
 398         }
 399         return NULL;
 400 }
 401
 402 static inline bool cachefiles_ondemand_finish_req(struct cachefiles_req *req,
 403                                                   struct xa_state *xas, int err)
 404 {
 405         if (unlikely(!xas || !req))
 406                 return false;
 407
 408         if (xa_cmpxchg(xas->xa, xas->xa_index, req, NULL, 0) != req)
 409                 return false;
 410
 411         req->error = err;
 412         complete(&req->done);
 413         return true;
 414 }
 415
 416 ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
 417                                         char __user *_buffer, size_t buflen)
 418 {
 419         struct cachefiles_req *req;
 420         struct cachefiles_msg *msg;
 421         size_t n;
 422         int ret = 0;
 423         struct ondemand_anon_file anon_file;
 424         XA_STATE(xas, &cache->reqs, cache->req_id_next);
 425
 426         xa_lock(&cache->reqs);
 427         /*
 428          * Cyclically search for a request that has not ever been processed,
 429          * to prevent requests from being processed repeatedly, and make
 430          * request distribution fair.
 431          */
 432         req = cachefiles_ondemand_select_req(&xas, ULONG_MAX);
 433         if (!req && cache->req_id_next > 0) {
 434                 xas_set(&xas, 0);
 435                 req = cachefiles_ondemand_select_req(&xas, cache->req_id_next - 1);
 436         }
 437         if (!req) {
 438                 xa_unlock(&cache->reqs);
 439                 return 0;
 440         }
 441
 442         msg = &req->msg;
 443         n = msg->len;
 444
 445         if (n > buflen) {
 446                 xa_unlock(&cache->reqs);
 447                 return -EMSGSIZE;
 448         }
 449
 450         xas_clear_mark(&xas, CACHEFILES_REQ_NEW);
 451         cache->req_id_next = xas.xa_index + 1;
 452         refcount_inc(&req->ref);
 453         cachefiles_grab_object(req->object, cachefiles_obj_get_read_req);
 454         xa_unlock(&cache->reqs);
 455
 456         if (msg->opcode == CACHEFILES_OP_OPEN) {
 457                 ret = cachefiles_ondemand_get_fd(req, &anon_file);
 458                 if (ret)
 459                         goto out;
 460         }
 461
 462         msg->msg_id = xas.xa_index;
 463         msg->object_id = req->object->ondemand->ondemand_id;
 464
 465         if (copy_to_user(_buffer, msg, n) != 0)
 466                 ret = -EFAULT;
 467
 468         if (msg->opcode == CACHEFILES_OP_OPEN) {
 469                 if (ret < 0) {
 470                         fput(anon_file.file);
 471                         put_unused_fd(anon_file.fd);
 472                         goto out;
 473                 }
 474                 fd_install(anon_file.fd, anon_file.file);
 475         }
 476 out:
 477         cachefiles_put_object(req->object, cachefiles_obj_put_read_req);
 478         /* Remove error request and CLOSE request has no reply */
 479         if (ret || msg->opcode == CACHEFILES_OP_CLOSE)
 480                 cachefiles_ondemand_finish_req(req, &xas, ret);
 481         cachefiles_req_put(req);
 482         return ret ? ret : n;
 483 }
 484
 485 typedef int (*init_req_fn)(struct cachefiles_req *req, void *private);
 486
 487 static int cachefiles_ondemand_send_req(struct cachefiles_object *object,
 488                                         enum cachefiles_opcode opcode,
 489                                         size_t data_len,
 490                                         init_req_fn init_req,
 491                                         void *private)
 492 {
 493         struct cachefiles_cache *cache = object->volume->cache;
 494         struct cachefiles_req *req = NULL;
 495         XA_STATE(xas, &cache->reqs, 0);
 496         int ret;
 497
 498         if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
 499                 return 0;
 500
 501         if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
 502                 ret = -EIO;
 503                 goto out;
 504         }
 505
 506         req = kzalloc(sizeof(*req) + data_len, GFP_KERNEL);
 507         if (!req) {
 508                 ret = -ENOMEM;
 509                 goto out;
 510         }
 511
 512         refcount_set(&req->ref, 1);
 513         req->object = object;
 514         init_completion(&req->done);
 515         req->msg.opcode = opcode;
 516         req->msg.len = sizeof(struct cachefiles_msg) + data_len;
 517
 518         ret = init_req(req, private);
 519         if (ret)
 520                 goto out;
 521
 522         do {
 523                 /*
 524                  * Stop enqueuing the request when daemon is dying. The
 525                  * following two operations need to be atomic as a whole.
 526                  *   1) check cache state, and
 527                  *   2) enqueue request if cache is alive.
 528                  * Otherwise the request may be enqueued after xarray has been
 529                  * flushed, leaving the orphan request never being completed.
 530                  *
 531                  * CPU 1                        CPU 2
 532                  * =====                        =====
 533                  *                              test CACHEFILES_DEAD bit
 534                  * set CACHEFILES_DEAD bit
 535                  * flush requests in the xarray
 536                  *                              enqueue the request
 537                  */
 538                 xas_lock(&xas);
 539
 540                 if (test_bit(CACHEFILES_DEAD, &cache->flags) ||
 541                     cachefiles_ondemand_object_is_dropping(object)) {
 542                         xas_unlock(&xas);
 543                         ret = -EIO;
 544                         goto out;
 545                 }
 546
 547                 /* coupled with the barrier in cachefiles_flush_reqs() */
 548                 smp_mb();
 549
 550                 if (opcode == CACHEFILES_OP_CLOSE &&
 551                     !cachefiles_ondemand_object_is_open(object)) {
 552                         WARN_ON_ONCE(object->ondemand->ondemand_id == 0);
 553                         xas_unlock(&xas);
 554                         ret = -EIO;
 555                         goto out;
 556                 }
 557
 558                 /*
 559                  * Cyclically find a free xas to avoid msg_id reuse that would
 560                  * cause the daemon to successfully copen a stale msg_id.
 561                  */
 562                 xas.xa_index = cache->msg_id_next;
 563                 xas_find_marked(&xas, UINT_MAX, XA_FREE_MARK);
 564                 if (xas.xa_node == XAS_RESTART) {
 565                         xas.xa_index = 0;
 566                         xas_find_marked(&xas, cache->msg_id_next - 1, XA_FREE_MARK);
 567                 }
 568                 if (xas.xa_node == XAS_RESTART)
 569                         xas_set_err(&xas, -EBUSY);
 570
 571                 xas_store(&xas, req);
 572                 if (xas_valid(&xas)) {
 573                         cache->msg_id_next = xas.xa_index + 1;
 574                         xas_clear_mark(&xas, XA_FREE_MARK);
 575                         xas_set_mark(&xas, CACHEFILES_REQ_NEW);
 576                 }
 577                 xas_unlock(&xas);
 578         } while (xas_nomem(&xas, GFP_KERNEL));
 579
 580         ret = xas_error(&xas);
 581         if (ret)
 582                 goto out;
 583
 584         wake_up_all(&cache->daemon_pollwq);
 585 wait:
 586         ret = wait_for_completion_killable(&req->done);
 587         if (!ret) {
 588                 ret = req->error;
 589         } else {
 590                 ret = -EINTR;
 591                 if (!cachefiles_ondemand_finish_req(req, &xas, ret)) {
 592                         /* Someone will complete it soon. */
 593                         cpu_relax();
 594                         goto wait;
 595                 }
 596         }
 597         cachefiles_req_put(req);
 598         return ret;
 599 out:
 600         /* Reset the object to close state in error handling path.
 601          * If error occurs after creating the anonymous fd,
 602          * cachefiles_ondemand_fd_release() will set object to close.
 603          */
 604         if (opcode == CACHEFILES_OP_OPEN &&
 605             !cachefiles_ondemand_object_is_dropping(object))
 606                 cachefiles_ondemand_set_object_close(object);
 607         kfree(req);
 608         return ret;
 609 }
 610
 611 static int cachefiles_ondemand_init_open_req(struct cachefiles_req *req,
 612                                              void *private)
 613 {
 614         struct cachefiles_object *object = req->object;
 615         struct fscache_cookie *cookie = object->cookie;
 616         struct fscache_volume *volume = object->volume->vcookie;
 617         struct cachefiles_open *load = (void *)req->msg.data;
 618         size_t volume_key_size, cookie_key_size;
 619         void *volume_key, *cookie_key;
 620
 621         /*
 622          * Volume key is a NUL-terminated string. key[0] stores strlen() of the
 623          * string, followed by the content of the string (excluding '\0').
 624          */
 625         volume_key_size = volume->key[0] + 1;
 626         volume_key = volume->key + 1;
 627
 628         /* Cookie key is binary data, which is netfs specific. */
 629         cookie_key_size = cookie->key_len;
 630         cookie_key = fscache_get_key(cookie);
 631
 632         if (!(object->cookie->advice & FSCACHE_ADV_WANT_CACHE_SIZE)) {
 633                 pr_err("WANT_CACHE_SIZE is needed for on-demand mode\n");
 634                 return -EINVAL;
 635         }
 636
 637         load->volume_key_size = volume_key_size;
 638         load->cookie_key_size = cookie_key_size;
 639         memcpy(load->data, volume_key, volume_key_size);
 640         memcpy(load->data + volume_key_size, cookie_key, cookie_key_size);
 641
 642         return 0;
 643 }
 644
 645 static int cachefiles_ondemand_init_close_req(struct cachefiles_req *req,
 646                                               void *private)
 647 {
 648         struct cachefiles_object *object = req->object;
 649
 650         if (!cachefiles_ondemand_object_is_open(object))
 651                 return -ENOENT;
 652
 653         trace_cachefiles_ondemand_close(object, &req->msg);
 654         return 0;
 655 }
 656
 657 struct cachefiles_read_ctx {
 658         loff_t off;
 659         size_t len;
 660 };
 661
 662 static int cachefiles_ondemand_init_read_req(struct cachefiles_req *req,
 663                                              void *private)
 664 {
 665         struct cachefiles_object *object = req->object;
 666         struct cachefiles_read *load = (void *)req->msg.data;
 667         struct cachefiles_read_ctx *read_ctx = private;
 668
 669         load->off = read_ctx->off;
 670         load->len = read_ctx->len;
 671         trace_cachefiles_ondemand_read(object, &req->msg, load);
 672         return 0;
 673 }
 674
 675 int cachefiles_ondemand_init_object(struct cachefiles_object *object)
 676 {
 677         struct fscache_cookie *cookie = object->cookie;
 678         struct fscache_volume *volume = object->volume->vcookie;
 679         size_t volume_key_size, cookie_key_size, data_len;
 680
 681         if (!object->ondemand)
 682                 return 0;
 683
 684         /*
 685          * CacheFiles will firstly check the cache file under the root cache
 686          * directory. If the coherency check failed, it will fallback to
 687          * creating a new tmpfile as the cache file. Reuse the previously
 688          * allocated object ID if any.
 689          */
 690         if (cachefiles_ondemand_object_is_open(object))
 691                 return 0;
 692
 693         volume_key_size = volume->key[0] + 1;
 694         cookie_key_size = cookie->key_len;
 695         data_len = sizeof(struct cachefiles_open) +
 696                    volume_key_size + cookie_key_size;
 697
 698         return cachefiles_ondemand_send_req(object, CACHEFILES_OP_OPEN,
 699                         data_len, cachefiles_ondemand_init_open_req, NULL);
 700 }
 701
 702 void cachefiles_ondemand_clean_object(struct cachefiles_object *object)
 703 {
 704         unsigned long index;
 705         struct cachefiles_req *req;
 706         struct cachefiles_cache *cache;
 707
 708         if (!object->ondemand)
 709                 return;
 710
 711         cachefiles_ondemand_send_req(object, CACHEFILES_OP_CLOSE, 0,
 712                         cachefiles_ondemand_init_close_req, NULL);
 713
 714         if (!object->ondemand->ondemand_id)
 715                 return;
 716
 717         /* Cancel all requests for the object that is being dropped. */
 718         cache = object->volume->cache;
 719         xa_lock(&cache->reqs);
 720         cachefiles_ondemand_set_object_dropping(object);
 721         xa_for_each(&cache->reqs, index, req) {
 722                 if (req->object == object) {
 723                         req->error = -EIO;
 724                         complete(&req->done);
 725                         __xa_erase(&cache->reqs, index);
 726                 }
 727         }
 728         xa_unlock(&cache->reqs);
 729
 730         /* Wait for ondemand_object_worker() to finish to avoid UAF. */
 731         cancel_work_sync(&object->ondemand->ondemand_work);
 732 }
 733
 734 int cachefiles_ondemand_init_obj_info(struct cachefiles_object *object,
 735                                 struct cachefiles_volume *volume)
 736 {
 737         if (!cachefiles_in_ondemand_mode(volume->cache))
 738                 return 0;
 739
 740         object->ondemand = kzalloc(sizeof(struct cachefiles_ondemand_info),
 741                                         GFP_KERNEL);
 742         if (!object->ondemand)
 743                 return -ENOMEM;
 744
 745         object->ondemand->object = object;
 746         spin_lock_init(&object->ondemand->lock);
 747         INIT_WORK(&object->ondemand->ondemand_work, ondemand_object_worker);
 748         return 0;
 749 }
 750
 751 void cachefiles_ondemand_deinit_obj_info(struct cachefiles_object *object)
 752 {
 753         kfree(object->ondemand);
 754         object->ondemand = NULL;
 755 }
 756
 757 int cachefiles_ondemand_read(struct cachefiles_object *object,
 758                              loff_t pos, size_t len)
 759 {
 760         struct cachefiles_read_ctx read_ctx = {pos, len};
 761
 762         return cachefiles_ondemand_send_req(object, CACHEFILES_OP_READ,
 763                         sizeof(struct cachefiles_read),
 764                         cachefiles_ondemand_init_read_req, &read_ctx);
 765 }