fs/fuse/file.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU GPL.
   6   See the file COPYING.
   7 */
   8
   9 #include "fuse_i.h"
  10
  11 #include <linux/pagemap.h>
  12 #include <linux/slab.h>
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/module.h>
  16 #include <linux/compat.h>
  17 #include <linux/swap.h>
  18 #include <linux/aio.h>
  19 #include <linux/falloc.h>
  20
  21 static const struct file_operations fuse_direct_io_file_operations;
  22
  23 static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
  24                           int opcode, struct fuse_open_out *outargp)
  25 {
  26         struct fuse_open_in inarg;
  27         struct fuse_req *req;
  28         int err;
  29
  30         req = fuse_get_req_nopages(fc);
  31         if (IS_ERR(req))
  32                 return PTR_ERR(req);
  33
  34         memset(&inarg, 0, sizeof(inarg));
  35         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
  36         if (!fc->atomic_o_trunc)
  37                 inarg.flags &= ~O_TRUNC;
  38         req->in.h.opcode = opcode;
  39         req->in.h.nodeid = nodeid;
  40         req->in.numargs = 1;
  41         req->in.args[0].size = sizeof(inarg);
  42         req->in.args[0].value = &inarg;
  43         req->out.numargs = 1;
  44         req->out.args[0].size = sizeof(*outargp);
  45         req->out.args[0].value = outargp;
  46         fuse_request_send(fc, req);
  47         err = req->out.h.error;
  48         fuse_put_request(fc, req);
  49
  50         return err;
  51 }
  52
  53 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
  54 {
  55         struct fuse_file *ff;
  56
  57         ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
  58         if (unlikely(!ff))
  59                 return NULL;
  60
  61         ff->fc = fc;
  62         ff->reserved_req = fuse_request_alloc(0);
  63         if (unlikely(!ff->reserved_req)) {
  64                 kfree(ff);
  65                 return NULL;
  66         }
  67
  68         INIT_LIST_HEAD(&ff->write_entry);
  69         atomic_set(&ff->count, 0);
  70         RB_CLEAR_NODE(&ff->polled_node);
  71         init_waitqueue_head(&ff->poll_wait);
  72
  73         spin_lock(&fc->lock);
  74         ff->kh = ++fc->khctr;
  75         spin_unlock(&fc->lock);
  76
  77         return ff;
  78 }
  79
  80 void fuse_file_free(struct fuse_file *ff)
  81 {
  82         fuse_request_free(ff->reserved_req);
  83         kfree(ff);
  84 }
  85
  86 struct fuse_file *fuse_file_get(struct fuse_file *ff)
  87 {
  88         atomic_inc(&ff->count);
  89         return ff;
  90 }
  91
  92 static void fuse_release_async(struct work_struct *work)
  93 {
  94         struct fuse_req *req;
  95         struct fuse_conn *fc;
  96         struct path path;
  97
  98         req = container_of(work, struct fuse_req, misc.release.work);
  99         path = req->misc.release.path;
 100         fc = get_fuse_conn(path.dentry->d_inode);
 101
 102         fuse_put_request(fc, req);
 103         path_put(&path);
 104 }
 105
 106 static void fuse_release_end(struct fuse_conn *fc, struct fuse_req *req)
 107 {
 108         if (fc->destroy_req) {
 109                 /*
 110                  * If this is a fuseblk mount, then it's possible that
 111                  * releasing the path will result in releasing the
 112                  * super block and sending the DESTROY request.  If
 113                  * the server is single threaded, this would hang.
 114                  * For this reason do the path_put() in a separate
 115                  * thread.
 116                  */
 117                 atomic_inc(&req->count);
 118                 INIT_WORK(&req->misc.release.work, fuse_release_async);
 119                 schedule_work(&req->misc.release.work);
 120         } else {
 121                 path_put(&req->misc.release.path);
 122         }
 123 }
 124
 125 static void fuse_file_put(struct fuse_file *ff, bool sync)
 126 {
 127         if (atomic_dec_and_test(&ff->count)) {
 128                 struct fuse_req *req = ff->reserved_req;
 129
 130                 if (ff->fc->no_open) {
 131                         /*
 132                          * Drop the release request when client does not
 133                          * implement 'open'
 134                          */
 135                         req->background = 0;
 136                         path_put(&req->misc.release.path);
 137                         fuse_put_request(ff->fc, req);
 138                 } else if (sync) {
 139                         req->background = 0;
 140                         fuse_request_send(ff->fc, req);
 141                         path_put(&req->misc.release.path);
 142                         fuse_put_request(ff->fc, req);
 143                 } else {
 144                         req->end = fuse_release_end;
 145                         req->background = 1;
 146                         fuse_request_send_background(ff->fc, req);
 147                 }
 148                 kfree(ff);
 149         }
 150 }
 151
 152 int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 153                  bool isdir)
 154 {
 155         struct fuse_file *ff;
 156         int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
 157
 158         ff = fuse_file_alloc(fc);
 159         if (!ff)
 160                 return -ENOMEM;
 161
 162         ff->fh = 0;
 163         ff->open_flags = FOPEN_KEEP_CACHE; /* Default for no-open */
 164         if (!fc->no_open || isdir) {
 165                 struct fuse_open_out outarg;
 166                 int err;
 167
 168                 err = fuse_send_open(fc, nodeid, file, opcode, &outarg);
 169                 if (!err) {
 170                         ff->fh = outarg.fh;
 171                         ff->open_flags = outarg.open_flags;
 172
 173                 } else if (err != -ENOSYS || isdir) {
 174                         fuse_file_free(ff);
 175                         return err;
 176                 } else {
 177                         fc->no_open = 1;
 178                 }
 179         }
 180
 181         if (isdir)
 182                 ff->open_flags &= ~FOPEN_DIRECT_IO;
 183
 184         ff->nodeid = nodeid;
 185         file->private_data = fuse_file_get(ff);
 186
 187         return 0;
 188 }
 189 EXPORT_SYMBOL_GPL(fuse_do_open);
 190
 191 static void fuse_link_write_file(struct file *file)
 192 {
 193         struct inode *inode = file_inode(file);
 194         struct fuse_conn *fc = get_fuse_conn(inode);
 195         struct fuse_inode *fi = get_fuse_inode(inode);
 196         struct fuse_file *ff = file->private_data;
 197         /*
 198          * file may be written through mmap, so chain it onto the
 199          * inodes's write_file list
 200          */
 201         spin_lock(&fc->lock);
 202         if (list_empty(&ff->write_entry))
 203                 list_add(&ff->write_entry, &fi->write_files);
 204         spin_unlock(&fc->lock);
 205 }
 206
 207 void fuse_finish_open(struct inode *inode, struct file *file)
 208 {
 209         struct fuse_file *ff = file->private_data;
 210         struct fuse_conn *fc = get_fuse_conn(inode);
 211
 212         if (ff->open_flags & FOPEN_DIRECT_IO)
 213                 file->f_op = &fuse_direct_io_file_operations;
 214         if (!(ff->open_flags & FOPEN_KEEP_CACHE))
 215                 invalidate_inode_pages2(inode->i_mapping);
 216         if (ff->open_flags & FOPEN_NONSEEKABLE)
 217                 nonseekable_open(inode, file);
 218         if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {
 219                 struct fuse_inode *fi = get_fuse_inode(inode);
 220
 221                 spin_lock(&fc->lock);
 222                 fi->attr_version = ++fc->attr_version;
 223                 i_size_write(inode, 0);
 224                 spin_unlock(&fc->lock);
 225                 fuse_invalidate_attr(inode);
 226                 if (fc->writeback_cache)
 227                         file_update_time(file);
 228         }
 229         if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)
 230                 fuse_link_write_file(file);
 231 }
 232
 233 int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
 234 {
 235         struct fuse_conn *fc = get_fuse_conn(inode);
 236         int err;
 237         bool lock_inode = (file->f_flags & O_TRUNC) &&
 238                           fc->atomic_o_trunc &&
 239                           fc->writeback_cache;
 240
 241         err = generic_file_open(inode, file);
 242         if (err)
 243                 return err;
 244
 245         if (lock_inode)
 246                 mutex_lock(&inode->i_mutex);
 247
 248         err = fuse_do_open(fc, get_node_id(inode), file, isdir);
 249
 250         if (!err)
 251                 fuse_finish_open(inode, file);
 252
 253         if (lock_inode)
 254                 mutex_unlock(&inode->i_mutex);
 255
 256         return err;
 257 }
 258
 259 static void fuse_prepare_release(struct fuse_file *ff, int flags, int opcode)
 260 {
 261         struct fuse_conn *fc = ff->fc;
 262         struct fuse_req *req = ff->reserved_req;
 263         struct fuse_release_in *inarg = &req->misc.release.in;
 264
 265         spin_lock(&fc->lock);
 266         list_del(&ff->write_entry);
 267         if (!RB_EMPTY_NODE(&ff->polled_node))
 268                 rb_erase(&ff->polled_node, &fc->polled_files);
 269         spin_unlock(&fc->lock);
 270
 271         wake_up_interruptible_all(&ff->poll_wait);
 272
 273         inarg->fh = ff->fh;
 274         inarg->flags = flags;
 275         req->in.h.opcode = opcode;
 276         req->in.h.nodeid = ff->nodeid;
 277         req->in.numargs = 1;
 278         req->in.args[0].size = sizeof(struct fuse_release_in);
 279         req->in.args[0].value = inarg;
 280 }
 281
 282 void fuse_release_common(struct file *file, int opcode)
 283 {
 284         struct fuse_file *ff;
 285         struct fuse_req *req;
 286
 287         ff = file->private_data;
 288         if (unlikely(!ff))
 289                 return;
 290
 291         req = ff->reserved_req;
 292         fuse_prepare_release(ff, file->f_flags, opcode);
 293
 294         if (ff->flock) {
 295                 struct fuse_release_in *inarg = &req->misc.release.in;
 296                 inarg->release_flags |= FUSE_RELEASE_FLOCK_UNLOCK;
 297                 inarg->lock_owner = fuse_lock_owner_id(ff->fc,
 298                                                        (fl_owner_t) file);
 299         }
 300         /* Hold vfsmount and dentry until release is finished */
 301         path_get(&file->f_path);
 302         req->misc.release.path = file->f_path;
 303
 304         /*
 305          * Normally this will send the RELEASE request, however if
 306          * some asynchronous READ or WRITE requests are outstanding,
 307          * the sending will be delayed.
 308          *
 309          * Make the release synchronous if this is a fuseblk mount,
 310          * synchronous RELEASE is allowed (and desirable) in this case
 311          * because the server can be trusted not to screw up.
 312          */
 313         fuse_file_put(ff, ff->fc->destroy_req != NULL);
 314 }
 315
 316 static int fuse_open(struct inode *inode, struct file *file)
 317 {
 318         return fuse_open_common(inode, file, false);
 319 }
 320
 321 static int fuse_release(struct inode *inode, struct file *file)
 322 {
 323         struct fuse_conn *fc = get_fuse_conn(inode);
 324
 325         /* see fuse_vma_close() for !writeback_cache case */
 326         if (fc->writeback_cache)
 327                 write_inode_now(inode, 1);
 328
 329         fuse_release_common(file, FUSE_RELEASE);
 330
 331         /* return value is ignored by VFS */
 332         return 0;
 333 }
 334
 335 void fuse_sync_release(struct fuse_file *ff, int flags)
 336 {
 337         WARN_ON(atomic_read(&ff->count) > 1);
 338         fuse_prepare_release(ff, flags, FUSE_RELEASE);
 339         ff->reserved_req->force = 1;
 340         ff->reserved_req->background = 0;
 341         fuse_request_send(ff->fc, ff->reserved_req);
 342         fuse_put_request(ff->fc, ff->reserved_req);
 343         kfree(ff);
 344 }
 345 EXPORT_SYMBOL_GPL(fuse_sync_release);
 346
 347 /*
 348  * Scramble the ID space with XTEA, so that the value of the files_struct
 349  * pointer is not exposed to userspace.
 350  */
 351 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
 352 {
 353         u32 *k = fc->scramble_key;
 354         u64 v = (unsigned long) id;
 355         u32 v0 = v;
 356         u32 v1 = v >> 32;
 357         u32 sum = 0;
 358         int i;
 359
 360         for (i = 0; i < 32; i++) {
 361                 v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
 362                 sum += 0x9E3779B9;
 363                 v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
 364         }
 365
 366         return (u64) v0 + ((u64) v1 << 32);
 367 }
 368
 369 /*
 370  * Check if any page in a range is under writeback
 371  *
 372  * This is currently done by walking the list of writepage requests
 373  * for the inode, which can be pretty inefficient.
 374  */
 375 static bool fuse_range_is_writeback(struct inode *inode, pgoff_t idx_from,
 376                                    pgoff_t idx_to)
 377 {
 378         struct fuse_conn *fc = get_fuse_conn(inode);
 379         struct fuse_inode *fi = get_fuse_inode(inode);
 380         struct fuse_req *req;
 381         bool found = false;
 382
 383         spin_lock(&fc->lock);
 384         list_for_each_entry(req, &fi->writepages, writepages_entry) {
 385                 pgoff_t curr_index;
 386
 387                 BUG_ON(req->inode != inode);
 388                 curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT;
 389                 if (idx_from < curr_index + req->num_pages &&
 390                     curr_index <= idx_to) {
 391                         found = true;
 392                         break;
 393                 }
 394         }
 395         spin_unlock(&fc->lock);
 396
 397         return found;
 398 }
 399
 400 static inline bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
 401 {
 402         return fuse_range_is_writeback(inode, index, index);
 403 }
 404
 405 /*
 406  * Wait for page writeback to be completed.
 407  *
 408  * Since fuse doesn't rely on the VM writeback tracking, this has to
 409  * use some other means.
 410  */
 411 static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
 412 {
 413         struct fuse_inode *fi = get_fuse_inode(inode);
 414
 415         wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
 416         return 0;
 417 }
 418
 419 /*
 420  * Wait for all pending writepages on the inode to finish.
 421  *
 422  * This is currently done by blocking further writes with FUSE_NOWRITE
 423  * and waiting for all sent writes to complete.
 424  *
 425  * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
 426  * could conflict with truncation.
 427  */
 428 static void fuse_sync_writes(struct inode *inode)
 429 {
 430         fuse_set_nowrite(inode);
 431         fuse_release_nowrite(inode);
 432 }
 433
 434 static int fuse_flush(struct file *file, fl_owner_t id)
 435 {
 436         struct inode *inode = file_inode(file);
 437         struct fuse_conn *fc = get_fuse_conn(inode);
 438         struct fuse_file *ff = file->private_data;
 439         struct fuse_req *req;
 440         struct fuse_flush_in inarg;
 441         int err;
 442
 443         if (is_bad_inode(inode))
 444                 return -EIO;
 445
 446         if (fc->no_flush)
 447                 return 0;
 448
 449         err = write_inode_now(inode, 1);
 450         if (err)
 451                 return err;
 452
 453         mutex_lock(&inode->i_mutex);
 454         fuse_sync_writes(inode);
 455         mutex_unlock(&inode->i_mutex);
 456
 457         req = fuse_get_req_nofail_nopages(fc, file);
 458         memset(&inarg, 0, sizeof(inarg));
 459         inarg.fh = ff->fh;
 460         inarg.lock_owner = fuse_lock_owner_id(fc, id);
 461         req->in.h.opcode = FUSE_FLUSH;
 462         req->in.h.nodeid = get_node_id(inode);
 463         req->in.numargs = 1;
 464         req->in.args[0].size = sizeof(inarg);
 465         req->in.args[0].value = &inarg;
 466         req->force = 1;
 467         fuse_request_send(fc, req);
 468         err = req->out.h.error;
 469         fuse_put_request(fc, req);
 470         if (err == -ENOSYS) {
 471                 fc->no_flush = 1;
 472                 err = 0;
 473         }
 474         return err;
 475 }
 476
 477 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
 478                       int datasync, int isdir)
 479 {
 480         struct inode *inode = file->f_mapping->host;
 481         struct fuse_conn *fc = get_fuse_conn(inode);
 482         struct fuse_file *ff = file->private_data;
 483         struct fuse_req *req;
 484         struct fuse_fsync_in inarg;
 485         int err;
 486
 487         if (is_bad_inode(inode))
 488                 return -EIO;
 489
 490         mutex_lock(&inode->i_mutex);
 491
 492         /*
 493          * Start writeback against all dirty pages of the inode, then
 494          * wait for all outstanding writes, before sending the FSYNC
 495          * request.
 496          */
 497         err = filemap_write_and_wait_range(inode->i_mapping, start, end);
 498         if (err)
 499                 goto out;
 500
 501         fuse_sync_writes(inode);
 502         err = sync_inode_metadata(inode, 1);
 503         if (err)
 504                 goto out;
 505
 506         if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
 507                 goto out;
 508
 509         req = fuse_get_req_nopages(fc);
 510         if (IS_ERR(req)) {
 511                 err = PTR_ERR(req);
 512                 goto out;
 513         }
 514
 515         memset(&inarg, 0, sizeof(inarg));
 516         inarg.fh = ff->fh;
 517         inarg.fsync_flags = datasync ? 1 : 0;
 518         req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
 519         req->in.h.nodeid = get_node_id(inode);
 520         req->in.numargs = 1;
 521         req->in.args[0].size = sizeof(inarg);
 522         req->in.args[0].value = &inarg;
 523         fuse_request_send(fc, req);
 524         err = req->out.h.error;
 525         fuse_put_request(fc, req);
 526         if (err == -ENOSYS) {
 527                 if (isdir)
 528                         fc->no_fsyncdir = 1;
 529                 else
 530                         fc->no_fsync = 1;
 531                 err = 0;
 532         }
 533 out:
 534         mutex_unlock(&inode->i_mutex);
 535         return err;
 536 }
 537
 538 static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 539                       int datasync)
 540 {
 541         return fuse_fsync_common(file, start, end, datasync, 0);
 542 }
 543
 544 void fuse_read_fill(struct fuse_req *req, struct file *file, loff_t pos,
 545                     size_t count, int opcode)
 546 {
 547         struct fuse_read_in *inarg = &req->misc.read.in;
 548         struct fuse_file *ff = file->private_data;
 549
 550         inarg->fh = ff->fh;
 551         inarg->offset = pos;
 552         inarg->size = count;
 553         inarg->flags = file->f_flags;
 554         req->in.h.opcode = opcode;
 555         req->in.h.nodeid = ff->nodeid;
 556         req->in.numargs = 1;
 557         req->in.args[0].size = sizeof(struct fuse_read_in);
 558         req->in.args[0].value = inarg;
 559         req->out.argvar = 1;
 560         req->out.numargs = 1;
 561         req->out.args[0].size = count;
 562 }
 563
 564 static void fuse_release_user_pages(struct fuse_req *req, int write)
 565 {
 566         unsigned i;
 567
 568         for (i = 0; i < req->num_pages; i++) {
 569                 struct page *page = req->pages[i];
 570                 if (write)
 571                         set_page_dirty_lock(page);
 572                 put_page(page);
 573         }
 574 }
 575
 576 /**
 577  * In case of short read, the caller sets 'pos' to the position of
 578  * actual end of fuse request in IO request. Otherwise, if bytes_requested
 579  * == bytes_transferred or rw == WRITE, the caller sets 'pos' to -1.
 580  *
 581  * An example:
 582  * User requested DIO read of 64K. It was splitted into two 32K fuse requests,
 583  * both submitted asynchronously. The first of them was ACKed by userspace as
 584  * fully completed (req->out.args[0].size == 32K) resulting in pos == -1. The
 585  * second request was ACKed as short, e.g. only 1K was read, resulting in
 586  * pos == 33K.
 587  *
 588  * Thus, when all fuse requests are completed, the minimal non-negative 'pos'
 589  * will be equal to the length of the longest contiguous fragment of
 590  * transferred data starting from the beginning of IO request.
 591  */
 592 static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
 593 {
 594         int left;
 595
 596         spin_lock(&io->lock);
 597         if (err)
 598                 io->err = io->err ? : err;
 599         else if (pos >= 0 && (io->bytes < 0 || pos < io->bytes))
 600                 io->bytes = pos;
 601
 602         left = --io->reqs;
 603         spin_unlock(&io->lock);
 604
 605         if (!left) {
 606                 long res;
 607
 608                 if (io->err)
 609                         res = io->err;
 610                 else if (io->bytes >= 0 && io->write)
 611                         res = -EIO;
 612                 else {
 613                         res = io->bytes < 0 ? io->size : io->bytes;
 614
 615                         if (!is_sync_kiocb(io->iocb)) {
 616                                 struct inode *inode = file_inode(io->iocb->ki_filp);
 617                                 struct fuse_conn *fc = get_fuse_conn(inode);
 618                                 struct fuse_inode *fi = get_fuse_inode(inode);
 619
 620                                 spin_lock(&fc->lock);
 621                                 fi->attr_version = ++fc->attr_version;
 622                                 spin_unlock(&fc->lock);
 623                         }
 624                 }
 625
 626                 aio_complete(io->iocb, res, 0);
 627                 kfree(io);
 628         }
 629 }
 630
 631 static void fuse_aio_complete_req(struct fuse_conn *fc, struct fuse_req *req)
 632 {
 633         struct fuse_io_priv *io = req->io;
 634         ssize_t pos = -1;
 635
 636         fuse_release_user_pages(req, !io->write);
 637
 638         if (io->write) {
 639                 if (req->misc.write.in.size != req->misc.write.out.size)
 640                         pos = req->misc.write.in.offset - io->offset +
 641                                 req->misc.write.out.size;
 642         } else {
 643                 if (req->misc.read.in.size != req->out.args[0].size)
 644                         pos = req->misc.read.in.offset - io->offset +
 645                                 req->out.args[0].size;
 646         }
 647
 648         fuse_aio_complete(io, req->out.h.error, pos);
 649 }
 650
 651 static size_t fuse_async_req_send(struct fuse_conn *fc, struct fuse_req *req,
 652                 size_t num_bytes, struct fuse_io_priv *io)
 653 {
 654         spin_lock(&io->lock);
 655         io->size += num_bytes;
 656         io->reqs++;
 657         spin_unlock(&io->lock);
 658
 659         req->io = io;
 660         req->end = fuse_aio_complete_req;
 661
 662         __fuse_get_request(req);
 663         fuse_request_send_background(fc, req);
 664
 665         return num_bytes;
 666 }
 667
 668 static size_t fuse_send_read(struct fuse_req *req, struct fuse_io_priv *io,
 669                              loff_t pos, size_t count, fl_owner_t owner)
 670 {
 671         struct file *file = io->file;
 672         struct fuse_file *ff = file->private_data;
 673         struct fuse_conn *fc = ff->fc;
 674
 675         fuse_read_fill(req, file, pos, count, FUSE_READ);
 676         if (owner != NULL) {
 677                 struct fuse_read_in *inarg = &req->misc.read.in;
 678
 679                 inarg->read_flags |= FUSE_READ_LOCKOWNER;
 680                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 681         }
 682
 683         if (io->async)
 684                 return fuse_async_req_send(fc, req, count, io);
 685
 686         fuse_request_send(fc, req);
 687         return req->out.args[0].size;
 688 }
 689
 690 static void fuse_read_update_size(struct inode *inode, loff_t size,
 691                                   u64 attr_ver)
 692 {
 693         struct fuse_conn *fc = get_fuse_conn(inode);
 694         struct fuse_inode *fi = get_fuse_inode(inode);
 695
 696         spin_lock(&fc->lock);
 697         if (attr_ver == fi->attr_version && size < inode->i_size &&
 698             !test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
 699                 fi->attr_version = ++fc->attr_version;
 700                 i_size_write(inode, size);
 701         }
 702         spin_unlock(&fc->lock);
 703 }
 704
 705 static void fuse_short_read(struct fuse_req *req, struct inode *inode,
 706                             u64 attr_ver)
 707 {
 708         size_t num_read = req->out.args[0].size;
 709         struct fuse_conn *fc = get_fuse_conn(inode);
 710
 711         if (fc->writeback_cache) {
 712                 /*
 713                  * A hole in a file. Some data after the hole are in page cache,
 714                  * but have not reached the client fs yet. So, the hole is not
 715                  * present there.
 716                  */
 717                 int i;
 718                 int start_idx = num_read >> PAGE_CACHE_SHIFT;
 719                 size_t off = num_read & (PAGE_CACHE_SIZE - 1);
 720
 721                 for (i = start_idx; i < req->num_pages; i++) {
 722                         zero_user_segment(req->pages[i], off, PAGE_CACHE_SIZE);
 723                         off = 0;
 724                 }
 725         } else {
 726                 loff_t pos = page_offset(req->pages[0]) + num_read;
 727                 fuse_read_update_size(inode, pos, attr_ver);
 728         }
 729 }
 730
 731 static int fuse_do_readpage(struct file *file, struct page *page)
 732 {
 733         struct fuse_io_priv io = { .async = 0, .file = file };
 734         struct inode *inode = page->mapping->host;
 735         struct fuse_conn *fc = get_fuse_conn(inode);
 736         struct fuse_req *req;
 737         size_t num_read;
 738         loff_t pos = page_offset(page);
 739         size_t count = PAGE_CACHE_SIZE;
 740         u64 attr_ver;
 741         int err;
 742
 743         /*
 744          * Page writeback can extend beyond the lifetime of the
 745          * page-cache page, so make sure we read a properly synced
 746          * page.
 747          */
 748         fuse_wait_on_page_writeback(inode, page->index);
 749
 750         req = fuse_get_req(fc, 1);
 751         if (IS_ERR(req))
 752                 return PTR_ERR(req);
 753
 754         attr_ver = fuse_get_attr_version(fc);
 755
 756         req->out.page_zeroing = 1;
 757         req->out.argpages = 1;
 758         req->num_pages = 1;
 759         req->pages[0] = page;
 760         req->page_descs[0].length = count;
 761         num_read = fuse_send_read(req, &io, pos, count, NULL);
 762         err = req->out.h.error;
 763
 764         if (!err) {
 765                 /*
 766                  * Short read means EOF.  If file size is larger, truncate it
 767                  */
 768                 if (num_read < count)
 769                         fuse_short_read(req, inode, attr_ver);
 770
 771                 SetPageUptodate(page);
 772         }
 773
 774         fuse_put_request(fc, req);
 775
 776         return err;
 777 }
 778
 779 static int fuse_readpage(struct file *file, struct page *page)
 780 {
 781         struct inode *inode = page->mapping->host;
 782         int err;
 783
 784         err = -EIO;
 785         if (is_bad_inode(inode))
 786                 goto out;
 787
 788         err = fuse_do_readpage(file, page);
 789         fuse_invalidate_atime(inode);
 790  out:
 791         unlock_page(page);
 792         return err;
 793 }
 794
 795 static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
 796 {
 797         int i;
 798         size_t count = req->misc.read.in.size;
 799         size_t num_read = req->out.args[0].size;
 800         struct address_space *mapping = NULL;
 801
 802         for (i = 0; mapping == NULL && i < req->num_pages; i++)
 803                 mapping = req->pages[i]->mapping;
 804
 805         if (mapping) {
 806                 struct inode *inode = mapping->host;
 807
 808                 /*
 809                  * Short read means EOF. If file size is larger, truncate it
 810                  */
 811                 if (!req->out.h.error && num_read < count)
 812                         fuse_short_read(req, inode, req->misc.read.attr_ver);
 813
 814                 fuse_invalidate_atime(inode);
 815         }
 816
 817         for (i = 0; i < req->num_pages; i++) {
 818                 struct page *page = req->pages[i];
 819                 if (!req->out.h.error)
 820                         SetPageUptodate(page);
 821                 else
 822                         SetPageError(page);
 823                 unlock_page(page);
 824                 page_cache_release(page);
 825         }
 826         if (req->ff)
 827                 fuse_file_put(req->ff, false);
 828 }
 829
 830 static void fuse_send_readpages(struct fuse_req *req, struct file *file)
 831 {
 832         struct fuse_file *ff = file->private_data;
 833         struct fuse_conn *fc = ff->fc;
 834         loff_t pos = page_offset(req->pages[0]);
 835         size_t count = req->num_pages << PAGE_CACHE_SHIFT;
 836
 837         req->out.argpages = 1;
 838         req->out.page_zeroing = 1;
 839         req->out.page_replace = 1;
 840         fuse_read_fill(req, file, pos, count, FUSE_READ);
 841         req->misc.read.attr_ver = fuse_get_attr_version(fc);
 842         if (fc->async_read) {
 843                 req->ff = fuse_file_get(ff);
 844                 req->end = fuse_readpages_end;
 845                 fuse_request_send_background(fc, req);
 846         } else {
 847                 fuse_request_send(fc, req);
 848                 fuse_readpages_end(fc, req);
 849                 fuse_put_request(fc, req);
 850         }
 851 }
 852
 853 struct fuse_fill_data {
 854         struct fuse_req *req;
 855         struct file *file;
 856         struct inode *inode;
 857         unsigned nr_pages;
 858 };
 859
 860 static int fuse_readpages_fill(void *_data, struct page *page)
 861 {
 862         struct fuse_fill_data *data = _data;
 863         struct fuse_req *req = data->req;
 864         struct inode *inode = data->inode;
 865         struct fuse_conn *fc = get_fuse_conn(inode);
 866
 867         fuse_wait_on_page_writeback(inode, page->index);
 868
 869         if (req->num_pages &&
 870             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 871              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 872              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 873                 int nr_alloc = min_t(unsigned, data->nr_pages,
 874                                      FUSE_MAX_PAGES_PER_REQ);
 875                 fuse_send_readpages(req, data->file);
 876                 if (fc->async_read)
 877                         req = fuse_get_req_for_background(fc, nr_alloc);
 878                 else
 879                         req = fuse_get_req(fc, nr_alloc);
 880
 881                 data->req = req;
 882                 if (IS_ERR(req)) {
 883                         unlock_page(page);
 884                         return PTR_ERR(req);
 885                 }
 886         }
 887
 888         if (WARN_ON(req->num_pages >= req->max_pages)) {
 889                 fuse_put_request(fc, req);
 890                 return -EIO;
 891         }
 892
 893         page_cache_get(page);
 894         req->pages[req->num_pages] = page;
 895         req->page_descs[req->num_pages].length = PAGE_SIZE;
 896         req->num_pages++;
 897         data->nr_pages--;
 898         return 0;
 899 }
 900
 901 static int fuse_readpages(struct file *file, struct address_space *mapping,
 902                           struct list_head *pages, unsigned nr_pages)
 903 {
 904         struct inode *inode = mapping->host;
 905         struct fuse_conn *fc = get_fuse_conn(inode);
 906         struct fuse_fill_data data;
 907         int err;
 908         int nr_alloc = min_t(unsigned, nr_pages, FUSE_MAX_PAGES_PER_REQ);
 909
 910         err = -EIO;
 911         if (is_bad_inode(inode))
 912                 goto out;
 913
 914         data.file = file;
 915         data.inode = inode;
 916         if (fc->async_read)
 917                 data.req = fuse_get_req_for_background(fc, nr_alloc);
 918         else
 919                 data.req = fuse_get_req(fc, nr_alloc);
 920         data.nr_pages = nr_pages;
 921         err = PTR_ERR(data.req);
 922         if (IS_ERR(data.req))
 923                 goto out;
 924
 925         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 926         if (!err) {
 927                 if (data.req->num_pages)
 928                         fuse_send_readpages(data.req, file);
 929                 else
 930                         fuse_put_request(fc, data.req);
 931         }
 932 out:
 933         return err;
 934 }
 935
 936 static ssize_t fuse_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 937                                   unsigned long nr_segs, loff_t pos)
 938 {
 939         struct inode *inode = iocb->ki_filp->f_mapping->host;
 940         struct fuse_conn *fc = get_fuse_conn(inode);
 941
 942         /*
 943          * In auto invalidate mode, always update attributes on read.
 944          * Otherwise, only update if we attempt to read past EOF (to ensure
 945          * i_size is up to date).
 946          */
 947         if (fc->auto_inval_data ||
 948             (pos + iov_length(iov, nr_segs) > i_size_read(inode))) {
 949                 int err;
 950                 err = fuse_update_attributes(inode, NULL, iocb->ki_filp, NULL);
 951                 if (err)
 952                         return err;
 953         }
 954
 955         return generic_file_aio_read(iocb, iov, nr_segs, pos);
 956 }
 957
 958 static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,
 959                             loff_t pos, size_t count)
 960 {
 961         struct fuse_write_in *inarg = &req->misc.write.in;
 962         struct fuse_write_out *outarg = &req->misc.write.out;
 963
 964         inarg->fh = ff->fh;
 965         inarg->offset = pos;
 966         inarg->size = count;
 967         req->in.h.opcode = FUSE_WRITE;
 968         req->in.h.nodeid = ff->nodeid;
 969         req->in.numargs = 2;
 970         if (ff->fc->minor < 9)
 971                 req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
 972         else
 973                 req->in.args[0].size = sizeof(struct fuse_write_in);
 974         req->in.args[0].value = inarg;
 975         req->in.args[1].size = count;
 976         req->out.numargs = 1;
 977         req->out.args[0].size = sizeof(struct fuse_write_out);
 978         req->out.args[0].value = outarg;
 979 }
 980
 981 static size_t fuse_send_write(struct fuse_req *req, struct fuse_io_priv *io,
 982                               loff_t pos, size_t count, fl_owner_t owner)
 983 {
 984         struct file *file = io->file;
 985         struct fuse_file *ff = file->private_data;
 986         struct fuse_conn *fc = ff->fc;
 987         struct fuse_write_in *inarg = &req->misc.write.in;
 988
 989         fuse_write_fill(req, ff, pos, count);
 990         inarg->flags = file->f_flags;
 991         if (owner != NULL) {
 992                 inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
 993                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 994         }
 995
 996         if (io->async)
 997                 return fuse_async_req_send(fc, req, count, io);
 998
 999         fuse_request_send(fc, req);
1000         return req->misc.write.out.size;
1001 }
1002
1003 bool fuse_write_update_size(struct inode *inode, loff_t pos)
1004 {
1005         struct fuse_conn *fc = get_fuse_conn(inode);
1006         struct fuse_inode *fi = get_fuse_inode(inode);
1007         bool ret = false;
1008
1009         spin_lock(&fc->lock);
1010         fi->attr_version = ++fc->attr_version;
1011         if (pos > inode->i_size) {
1012                 i_size_write(inode, pos);
1013                 ret = true;
1014         }
1015         spin_unlock(&fc->lock);
1016
1017         return ret;
1018 }
1019
1020 static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
1021                                     struct inode *inode, loff_t pos,
1022                                     size_t count)
1023 {
1024         size_t res;
1025         unsigned offset;
1026         unsigned i;
1027         struct fuse_io_priv io = { .async = 0, .file = file };
1028
1029         for (i = 0; i < req->num_pages; i++)
1030                 fuse_wait_on_page_writeback(inode, req->pages[i]->index);
1031
1032         res = fuse_send_write(req, &io, pos, count, NULL);
1033
1034         offset = req->page_descs[0].offset;
1035         count = res;
1036         for (i = 0; i < req->num_pages; i++) {
1037                 struct page *page = req->pages[i];
1038
1039                 if (!req->out.h.error && !offset && count >= PAGE_CACHE_SIZE)
1040                         SetPageUptodate(page);
1041
1042                 if (count > PAGE_CACHE_SIZE - offset)
1043                         count -= PAGE_CACHE_SIZE - offset;
1044                 else
1045                         count = 0;
1046                 offset = 0;
1047
1048                 unlock_page(page);
1049                 page_cache_release(page);
1050         }
1051
1052         return res;
1053 }
1054
1055 static ssize_t fuse_fill_write_pages(struct fuse_req *req,
1056                                struct address_space *mapping,
1057                                struct iov_iter *ii, loff_t pos)
1058 {
1059         struct fuse_conn *fc = get_fuse_conn(mapping->host);
1060         unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1061         size_t count = 0;
1062         int err;
1063
1064         req->in.argpages = 1;
1065         req->page_descs[0].offset = offset;
1066
1067         do {
1068                 size_t tmp;
1069                 struct page *page;
1070                 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1071                 size_t bytes = min_t(size_t, PAGE_CACHE_SIZE - offset,
1072                                      iov_iter_count(ii));
1073
1074                 bytes = min_t(size_t, bytes, fc->max_write - count);
1075
1076  again:
1077                 err = -EFAULT;
1078                 if (iov_iter_fault_in_readable(ii, bytes))
1079                         break;
1080
1081                 err = -ENOMEM;
1082                 page = grab_cache_page_write_begin(mapping, index, 0);
1083                 if (!page)
1084                         break;
1085
1086                 if (mapping_writably_mapped(mapping))
1087                         flush_dcache_page(page);
1088
1089                 tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
1090                 flush_dcache_page(page);
1091
1092                 mark_page_accessed(page);
1093
1094                 if (!tmp) {
1095                         unlock_page(page);
1096                         page_cache_release(page);
1097                         bytes = min(bytes, iov_iter_single_seg_count(ii));
1098                         goto again;
1099                 }
1100
1101                 err = 0;
1102                 req->pages[req->num_pages] = page;
1103                 req->page_descs[req->num_pages].length = tmp;
1104                 req->num_pages++;
1105
1106                 iov_iter_advance(ii, tmp);
1107                 count += tmp;
1108                 pos += tmp;
1109                 offset += tmp;
1110                 if (offset == PAGE_CACHE_SIZE)
1111                         offset = 0;
1112
1113                 if (!fc->big_writes)
1114                         break;
1115         } while (iov_iter_count(ii) && count < fc->max_write &&
1116                  req->num_pages < req->max_pages && offset == 0);
1117
1118         return count > 0 ? count : err;
1119 }
1120
1121 static inline unsigned fuse_wr_pages(loff_t pos, size_t len)
1122 {
1123         return min_t(unsigned,
1124                      ((pos + len - 1) >> PAGE_CACHE_SHIFT) -
1125                      (pos >> PAGE_CACHE_SHIFT) + 1,
1126                      FUSE_MAX_PAGES_PER_REQ);
1127 }
1128
1129 static ssize_t fuse_perform_write(struct file *file,
1130                                   struct address_space *mapping,
1131                                   struct iov_iter *ii, loff_t pos)
1132 {
1133         struct inode *inode = mapping->host;
1134         struct fuse_conn *fc = get_fuse_conn(inode);
1135         struct fuse_inode *fi = get_fuse_inode(inode);
1136         int err = 0;
1137         ssize_t res = 0;
1138
1139         if (is_bad_inode(inode))
1140                 return -EIO;
1141
1142         if (inode->i_size < pos + iov_iter_count(ii))
1143                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1144
1145         do {
1146                 struct fuse_req *req;
1147                 ssize_t count;
1148                 unsigned nr_pages = fuse_wr_pages(pos, iov_iter_count(ii));
1149
1150                 req = fuse_get_req(fc, nr_pages);
1151                 if (IS_ERR(req)) {
1152                         err = PTR_ERR(req);
1153                         break;
1154                 }
1155
1156                 count = fuse_fill_write_pages(req, mapping, ii, pos);
1157                 if (count <= 0) {
1158                         err = count;
1159                 } else {
1160                         size_t num_written;
1161
1162                         num_written = fuse_send_write_pages(req, file, inode,
1163                                                             pos, count);
1164                         err = req->out.h.error;
1165                         if (!err) {
1166                                 res += num_written;
1167                                 pos += num_written;
1168
1169                                 /* break out of the loop on short write */
1170                                 if (num_written != count)
1171                                         err = -EIO;
1172                         }
1173                 }
1174                 fuse_put_request(fc, req);
1175         } while (!err && iov_iter_count(ii));
1176
1177         if (res > 0)
1178                 fuse_write_update_size(inode, pos);
1179
1180         clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1181         fuse_invalidate_attr(inode);
1182
1183         return res > 0 ? res : err;
1184 }
1185
1186 static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
1187                                    unsigned long nr_segs, loff_t pos)
1188 {
1189         struct file *file = iocb->ki_filp;
1190         struct address_space *mapping = file->f_mapping;
1191         size_t count = 0;
1192         size_t ocount = 0;
1193         ssize_t written = 0;
1194         ssize_t written_buffered = 0;
1195         struct inode *inode = mapping->host;
1196         ssize_t err;
1197         struct iov_iter i;
1198         loff_t endbyte = 0;
1199
1200         if (get_fuse_conn(inode)->writeback_cache) {
1201                 /* Update size (EOF optimization) and mode (SUID clearing) */
1202                 err = fuse_update_attributes(mapping->host, NULL, file, NULL);
1203                 if (err)
1204                         return err;
1205
1206                 return generic_file_aio_write(iocb, iov, nr_segs, pos);
1207         }
1208
1209         WARN_ON(iocb->ki_pos != pos);
1210
1211         ocount = 0;
1212         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1213         if (err)
1214                 return err;
1215
1216         count = ocount;
1217         mutex_lock(&inode->i_mutex);
1218
1219         /* We can write back this queue in page reclaim */
1220         current->backing_dev_info = mapping->backing_dev_info;
1221
1222         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1223         if (err)
1224                 goto out;
1225
1226         if (count == 0)
1227                 goto out;
1228
1229         err = file_remove_suid(file);
1230         if (err)
1231                 goto out;
1232
1233         err = file_update_time(file);
1234         if (err)
1235                 goto out;
1236
1237         if (file->f_flags & O_DIRECT) {
1238                 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
1239                                                     count, ocount);
1240                 if (written < 0 || written == count)
1241                         goto out;
1242
1243                 pos += written;
1244                 count -= written;
1245
1246                 iov_iter_init(&i, iov, nr_segs, count, written);
1247                 written_buffered = fuse_perform_write(file, mapping, &i, pos);
1248                 if (written_buffered < 0) {
1249                         err = written_buffered;
1250                         goto out;
1251                 }
1252                 endbyte = pos + written_buffered - 1;
1253
1254                 err = filemap_write_and_wait_range(file->f_mapping, pos,
1255                                                    endbyte);
1256                 if (err)
1257                         goto out;
1258
1259                 invalidate_mapping_pages(file->f_mapping,
1260                                          pos >> PAGE_CACHE_SHIFT,
1261                                          endbyte >> PAGE_CACHE_SHIFT);
1262
1263                 written += written_buffered;
1264                 iocb->ki_pos = pos + written_buffered;
1265         } else {
1266                 iov_iter_init(&i, iov, nr_segs, count, 0);
1267                 written = fuse_perform_write(file, mapping, &i, pos);
1268                 if (written >= 0)
1269                         iocb->ki_pos = pos + written;
1270         }
1271 out:
1272         current->backing_dev_info = NULL;
1273         mutex_unlock(&inode->i_mutex);
1274
1275         return written ? written : err;
1276 }
1277
1278 static inline void fuse_page_descs_length_init(struct fuse_req *req,
1279                 unsigned index, unsigned nr_pages)
1280 {
1281         int i;
1282
1283         for (i = index; i < index + nr_pages; i++)
1284                 req->page_descs[i].length = PAGE_SIZE -
1285                         req->page_descs[i].offset;
1286 }
1287
1288 static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii)
1289 {
1290         return (unsigned long)ii->iov->iov_base + ii->iov_offset;
1291 }
1292
1293 static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
1294                                         size_t max_size)
1295 {
1296         return min(iov_iter_single_seg_count(ii), max_size);
1297 }
1298
1299 static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
1300                                size_t *nbytesp, int write)
1301 {
1302         size_t nbytes = 0;  /* # bytes already packed in req */
1303
1304         /* Special case for kernel I/O: can copy directly into the buffer */
1305         if (segment_eq(get_fs(), KERNEL_DS)) {
1306                 unsigned long user_addr = fuse_get_user_addr(ii);
1307                 size_t frag_size = fuse_get_frag_size(ii, *nbytesp);
1308
1309                 if (write)
1310                         req->in.args[1].value = (void *) user_addr;
1311                 else
1312                         req->out.args[0].value = (void *) user_addr;
1313
1314                 iov_iter_advance(ii, frag_size);
1315                 *nbytesp = frag_size;
1316                 return 0;
1317         }
1318
1319         while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
1320                 unsigned npages;
1321                 unsigned long user_addr = fuse_get_user_addr(ii);
1322                 unsigned offset = user_addr & ~PAGE_MASK;
1323                 size_t frag_size = fuse_get_frag_size(ii, *nbytesp - nbytes);
1324                 int ret;
1325
1326                 unsigned n = req->max_pages - req->num_pages;
1327                 frag_size = min_t(size_t, frag_size, n << PAGE_SHIFT);
1328
1329                 npages = (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
1330                 npages = clamp(npages, 1U, n);
1331
1332                 ret = get_user_pages_fast(user_addr, npages, !write,
1333                                           &req->pages[req->num_pages]);
1334                 if (ret < 0)
1335                         return ret;
1336
1337                 npages = ret;
1338                 frag_size = min_t(size_t, frag_size,
1339                                   (npages << PAGE_SHIFT) - offset);
1340                 iov_iter_advance(ii, frag_size);
1341
1342                 req->page_descs[req->num_pages].offset = offset;
1343                 fuse_page_descs_length_init(req, req->num_pages, npages);
1344
1345                 req->num_pages += npages;
1346                 req->page_descs[req->num_pages - 1].length -=
1347                         (npages << PAGE_SHIFT) - offset - frag_size;
1348
1349                 nbytes += frag_size;
1350         }
1351
1352         if (write)
1353                 req->in.argpages = 1;
1354         else
1355                 req->out.argpages = 1;
1356
1357         *nbytesp = nbytes;
1358
1359         return 0;
1360 }
1361
1362 static inline int fuse_iter_npages(const struct iov_iter *ii_p)
1363 {
1364         struct iov_iter ii = *ii_p;
1365         int npages = 0;
1366
1367         while (iov_iter_count(&ii) && npages < FUSE_MAX_PAGES_PER_REQ) {
1368                 unsigned long user_addr = fuse_get_user_addr(&ii);
1369                 unsigned offset = user_addr & ~PAGE_MASK;
1370                 size_t frag_size = iov_iter_single_seg_count(&ii);
1371
1372                 npages += (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
1373                 iov_iter_advance(&ii, frag_size);
1374         }
1375
1376         return min(npages, FUSE_MAX_PAGES_PER_REQ);
1377 }
1378
1379 ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov,
1380                        unsigned long nr_segs, size_t count, loff_t *ppos,
1381                        int flags)
1382 {
1383         int write = flags & FUSE_DIO_WRITE;
1384         int cuse = flags & FUSE_DIO_CUSE;
1385         struct file *file = io->file;
1386         struct inode *inode = file->f_mapping->host;
1387         struct fuse_file *ff = file->private_data;
1388         struct fuse_conn *fc = ff->fc;
1389         size_t nmax = write ? fc->max_write : fc->max_read;
1390         loff_t pos = *ppos;
1391         pgoff_t idx_from = pos >> PAGE_CACHE_SHIFT;
1392         pgoff_t idx_to = (pos + count - 1) >> PAGE_CACHE_SHIFT;
1393         ssize_t res = 0;
1394         struct fuse_req *req;
1395         struct iov_iter ii;
1396
1397         iov_iter_init(&ii, iov, nr_segs, count, 0);
1398
1399         if (io->async)
1400                 req = fuse_get_req_for_background(fc, fuse_iter_npages(&ii));
1401         else
1402                 req = fuse_get_req(fc, fuse_iter_npages(&ii));
1403         if (IS_ERR(req))
1404                 return PTR_ERR(req);
1405
1406         if (!cuse && fuse_range_is_writeback(inode, idx_from, idx_to)) {
1407                 if (!write)
1408                         mutex_lock(&inode->i_mutex);
1409                 fuse_sync_writes(inode);
1410                 if (!write)
1411                         mutex_unlock(&inode->i_mutex);
1412         }
1413
1414         while (count) {
1415                 size_t nres;
1416                 fl_owner_t owner = current->files;
1417                 size_t nbytes = min(count, nmax);
1418                 int err = fuse_get_user_pages(req, &ii, &nbytes, write);
1419                 if (err) {
1420                         res = err;
1421                         break;
1422                 }
1423
1424                 if (write)
1425                         nres = fuse_send_write(req, io, pos, nbytes, owner);
1426                 else
1427                         nres = fuse_send_read(req, io, pos, nbytes, owner);
1428
1429                 if (!io->async)
1430                         fuse_release_user_pages(req, !write);
1431                 if (req->out.h.error) {
1432                         if (!res)
1433                                 res = req->out.h.error;
1434                         break;
1435                 } else if (nres > nbytes) {
1436                         res = -EIO;
1437                         break;
1438                 }
1439                 count -= nres;
1440                 res += nres;
1441                 pos += nres;
1442                 if (nres != nbytes)
1443                         break;
1444                 if (count) {
1445                         fuse_put_request(fc, req);
1446                         if (io->async)
1447                                 req = fuse_get_req_for_background(fc,
1448                                         fuse_iter_npages(&ii));
1449                         else
1450                                 req = fuse_get_req(fc, fuse_iter_npages(&ii));
1451                         if (IS_ERR(req))
1452                                 break;
1453                 }
1454         }
1455         if (!IS_ERR(req))
1456                 fuse_put_request(fc, req);
1457         if (res > 0)
1458                 *ppos = pos;
1459
1460         return res;
1461 }
1462 EXPORT_SYMBOL_GPL(fuse_direct_io);
1463
1464 static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
1465                                   const struct iovec *iov,
1466                                   unsigned long nr_segs, loff_t *ppos,
1467                                   size_t count)
1468 {
1469         ssize_t res;
1470         struct file *file = io->file;
1471         struct inode *inode = file_inode(file);
1472
1473         if (is_bad_inode(inode))
1474                 return -EIO;
1475
1476         res = fuse_direct_io(io, iov, nr_segs, count, ppos, 0);
1477
1478         fuse_invalidate_attr(inode);
1479
1480         return res;
1481 }
1482
1483 static ssize_t fuse_direct_read(struct file *file, char __user *buf,
1484                                      size_t count, loff_t *ppos)
1485 {
1486         struct fuse_io_priv io = { .async = 0, .file = file };
1487         struct iovec iov = { .iov_base = buf, .iov_len = count };
1488         return __fuse_direct_read(&io, &iov, 1, ppos, count);
1489 }
1490
1491 static ssize_t __fuse_direct_write(struct fuse_io_priv *io,
1492                                    const struct iovec *iov,
1493                                    unsigned long nr_segs, loff_t *ppos)
1494 {
1495         struct file *file = io->file;
1496         struct inode *inode = file_inode(file);
1497         size_t count = iov_length(iov, nr_segs);
1498         ssize_t res;
1499
1500         res = generic_write_checks(file, ppos, &count, 0);
1501         if (!res)
1502                 res = fuse_direct_io(io, iov, nr_segs, count, ppos,
1503                                      FUSE_DIO_WRITE);
1504
1505         fuse_invalidate_attr(inode);
1506
1507         return res;
1508 }
1509
1510 static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
1511                                  size_t count, loff_t *ppos)
1512 {
1513         struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
1514         struct inode *inode = file_inode(file);
1515         ssize_t res;
1516         struct fuse_io_priv io = { .async = 0, .file = file };
1517
1518         if (is_bad_inode(inode))
1519                 return -EIO;
1520
1521         /* Don't allow parallel writes to the same file */
1522         mutex_lock(&inode->i_mutex);
1523         res = __fuse_direct_write(&io, &iov, 1, ppos);
1524         if (res > 0)
1525                 fuse_write_update_size(inode, *ppos);
1526         mutex_unlock(&inode->i_mutex);
1527
1528         return res;
1529 }
1530
1531 static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
1532 {
1533         int i;
1534
1535         for (i = 0; i < req->num_pages; i++)
1536                 __free_page(req->pages[i]);
1537
1538         if (req->ff)
1539                 fuse_file_put(req->ff, false);
1540 }
1541
1542 static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
1543 {
1544         struct inode *inode = req->inode;
1545         struct fuse_inode *fi = get_fuse_inode(inode);
1546         struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
1547         int i;
1548
1549         list_del(&req->writepages_entry);
1550         for (i = 0; i < req->num_pages; i++) {
1551                 dec_bdi_stat(bdi, BDI_WRITEBACK);
1552                 dec_zone_page_state(req->pages[i], NR_WRITEBACK_TEMP);
1553                 bdi_writeout_inc(bdi);
1554         }
1555         wake_up(&fi->page_waitq);
1556 }
1557
1558 /* Called under fc->lock, may release and reacquire it */
1559 static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req,
1560                                 loff_t size)
1561 __releases(fc->lock)
1562 __acquires(fc->lock)
1563 {
1564         struct fuse_inode *fi = get_fuse_inode(req->inode);
1565         struct fuse_write_in *inarg = &req->misc.write.in;
1566         __u64 data_size = req->num_pages * PAGE_CACHE_SIZE;
1567
1568         if (!fc->connected)
1569                 goto out_free;
1570
1571         if (inarg->offset + data_size <= size) {
1572                 inarg->size = data_size;
1573         } else if (inarg->offset < size) {
1574                 inarg->size = size - inarg->offset;
1575         } else {
1576                 /* Got truncated off completely */
1577                 goto out_free;
1578         }
1579
1580         req->in.args[1].size = inarg->size;
1581         fi->writectr++;
1582         fuse_request_send_background_locked(fc, req);
1583         return;
1584
1585  out_free:
1586         fuse_writepage_finish(fc, req);
1587         spin_unlock(&fc->lock);
1588         fuse_writepage_free(fc, req);
1589         fuse_put_request(fc, req);
1590         spin_lock(&fc->lock);
1591 }
1592
1593 /*
1594  * If fi->writectr is positive (no truncate or fsync going on) send
1595  * all queued writepage requests.
1596  *
1597  * Called with fc->lock
1598  */
1599 void fuse_flush_writepages(struct inode *inode)
1600 __releases(fc->lock)
1601 __acquires(fc->lock)
1602 {
1603         struct fuse_conn *fc = get_fuse_conn(inode);
1604         struct fuse_inode *fi = get_fuse_inode(inode);
1605         size_t crop = i_size_read(inode);
1606         struct fuse_req *req;
1607
1608         while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
1609                 req = list_entry(fi->queued_writes.next, struct fuse_req, list);
1610                 list_del_init(&req->list);
1611                 fuse_send_writepage(fc, req, crop);
1612         }
1613 }
1614
1615 static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
1616 {
1617         struct inode *inode = req->inode;
1618         struct fuse_inode *fi = get_fuse_inode(inode);
1619
1620         mapping_set_error(inode->i_mapping, req->out.h.error);
1621         spin_lock(&fc->lock);
1622         while (req->misc.write.next) {
1623                 struct fuse_conn *fc = get_fuse_conn(inode);
1624                 struct fuse_write_in *inarg = &req->misc.write.in;
1625                 struct fuse_req *next = req->misc.write.next;
1626                 req->misc.write.next = next->misc.write.next;
1627                 next->misc.write.next = NULL;
1628                 next->ff = fuse_file_get(req->ff);
1629                 list_add(&next->writepages_entry, &fi->writepages);
1630
1631                 /*
1632                  * Skip fuse_flush_writepages() to make it easy to crop requests
1633                  * based on primary request size.
1634                  *
1635                  * 1st case (trivial): there are no concurrent activities using
1636                  * fuse_set/release_nowrite.  Then we're on safe side because
1637                  * fuse_flush_writepages() would call fuse_send_writepage()
1638                  * anyway.
1639                  *
1640                  * 2nd case: someone called fuse_set_nowrite and it is waiting
1641                  * now for completion of all in-flight requests.  This happens
1642                  * rarely and no more than once per page, so this should be
1643                  * okay.
1644                  *
1645                  * 3rd case: someone (e.g. fuse_do_setattr()) is in the middle
1646                  * of fuse_set_nowrite..fuse_release_nowrite section.  The fact
1647                  * that fuse_set_nowrite returned implies that all in-flight
1648                  * requests were completed along with all of their secondary
1649                  * requests.  Further primary requests are blocked by negative
1650                  * writectr.  Hence there cannot be any in-flight requests and
1651                  * no invocations of fuse_writepage_end() while we're in
1652                  * fuse_set_nowrite..fuse_release_nowrite section.
1653                  */
1654                 fuse_send_writepage(fc, next, inarg->offset + inarg->size);
1655         }
1656         fi->writectr--;
1657         fuse_writepage_finish(fc, req);
1658         spin_unlock(&fc->lock);
1659         fuse_writepage_free(fc, req);
1660 }
1661
1662 static struct fuse_file *__fuse_write_file_get(struct fuse_conn *fc,
1663                                                struct fuse_inode *fi)
1664 {
1665         struct fuse_file *ff = NULL;
1666
1667         spin_lock(&fc->lock);
1668         if (!list_empty(&fi->write_files)) {
1669                 ff = list_entry(fi->write_files.next, struct fuse_file,
1670                                 write_entry);
1671                 fuse_file_get(ff);
1672         }
1673         spin_unlock(&fc->lock);
1674
1675         return ff;
1676 }
1677
1678 static struct fuse_file *fuse_write_file_get(struct fuse_conn *fc,
1679                                              struct fuse_inode *fi)
1680 {
1681         struct fuse_file *ff = __fuse_write_file_get(fc, fi);
1682         WARN_ON(!ff);
1683         return ff;
1684 }
1685
1686 int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
1687 {
1688         struct fuse_conn *fc = get_fuse_conn(inode);
1689         struct fuse_inode *fi = get_fuse_inode(inode);
1690         struct fuse_file *ff;
1691         int err;
1692
1693         ff = __fuse_write_file_get(fc, fi);
1694         err = fuse_flush_times(inode, ff);
1695         if (ff)
1696                 fuse_file_put(ff, 0);
1697
1698         return err;
1699 }
1700
1701 static int fuse_writepage_locked(struct page *page)
1702 {
1703         struct address_space *mapping = page->mapping;
1704         struct inode *inode = mapping->host;
1705         struct fuse_conn *fc = get_fuse_conn(inode);
1706         struct fuse_inode *fi = get_fuse_inode(inode);
1707         struct fuse_req *req;
1708         struct page *tmp_page;
1709         int error = -ENOMEM;
1710
1711         set_page_writeback(page);
1712
1713         req = fuse_request_alloc_nofs(1);
1714         if (!req)
1715                 goto err;
1716
1717         req->background = 1; /* writeback always goes to bg_queue */
1718         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1719         if (!tmp_page)
1720                 goto err_free;
1721
1722         error = -EIO;
1723         req->ff = fuse_write_file_get(fc, fi);
1724         if (!req->ff)
1725                 goto err_free;
1726
1727         fuse_write_fill(req, req->ff, page_offset(page), 0);
1728
1729         copy_highpage(tmp_page, page);
1730         req->misc.write.in.write_flags |= FUSE_WRITE_CACHE;
1731         req->misc.write.next = NULL;
1732         req->in.argpages = 1;
1733         req->num_pages = 1;
1734         req->pages[0] = tmp_page;
1735         req->page_descs[0].offset = 0;
1736         req->page_descs[0].length = PAGE_SIZE;
1737         req->end = fuse_writepage_end;
1738         req->inode = inode;
1739
1740         inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK);
1741         inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
1742
1743         spin_lock(&fc->lock);
1744         list_add(&req->writepages_entry, &fi->writepages);
1745         list_add_tail(&req->list, &fi->queued_writes);
1746         fuse_flush_writepages(inode);
1747         spin_unlock(&fc->lock);
1748
1749         end_page_writeback(page);
1750
1751         return 0;
1752
1753 err_free:
1754         fuse_request_free(req);
1755 err:
1756         end_page_writeback(page);
1757         return error;
1758 }
1759
1760 static int fuse_writepage(struct page *page, struct writeback_control *wbc)
1761 {
1762         int err;
1763
1764         if (fuse_page_is_writeback(page->mapping->host, page->index)) {
1765                 /*
1766                  * ->writepages() should be called for sync() and friends.  We
1767                  * should only get here on direct reclaim and then we are
1768                  * allowed to skip a page which is already in flight
1769                  */
1770                 WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
1771
1772                 redirty_page_for_writepage(wbc, page);
1773                 return 0;
1774         }
1775
1776         err = fuse_writepage_locked(page);
1777         unlock_page(page);
1778
1779         return err;
1780 }
1781
1782 struct fuse_fill_wb_data {
1783         struct fuse_req *req;
1784         struct fuse_file *ff;
1785         struct inode *inode;
1786         struct page **orig_pages;
1787 };
1788
1789 static void fuse_writepages_send(struct fuse_fill_wb_data *data)
1790 {
1791         struct fuse_req *req = data->req;
1792         struct inode *inode = data->inode;
1793         struct fuse_conn *fc = get_fuse_conn(inode);
1794         struct fuse_inode *fi = get_fuse_inode(inode);
1795         int num_pages = req->num_pages;
1796         int i;
1797
1798         req->ff = fuse_file_get(data->ff);
1799         spin_lock(&fc->lock);
1800         list_add_tail(&req->list, &fi->queued_writes);
1801         fuse_flush_writepages(inode);
1802         spin_unlock(&fc->lock);
1803
1804         for (i = 0; i < num_pages; i++)
1805                 end_page_writeback(data->orig_pages[i]);
1806 }
1807
1808 static bool fuse_writepage_in_flight(struct fuse_req *new_req,
1809                                      struct page *page)
1810 {
1811         struct fuse_conn *fc = get_fuse_conn(new_req->inode);
1812         struct fuse_inode *fi = get_fuse_inode(new_req->inode);
1813         struct fuse_req *tmp;
1814         struct fuse_req *old_req;
1815         bool found = false;
1816         pgoff_t curr_index;
1817
1818         BUG_ON(new_req->num_pages != 0);
1819
1820         spin_lock(&fc->lock);
1821         list_del(&new_req->writepages_entry);
1822         list_for_each_entry(old_req, &fi->writepages, writepages_entry) {
1823                 BUG_ON(old_req->inode != new_req->inode);
1824                 curr_index = old_req->misc.write.in.offset >> PAGE_CACHE_SHIFT;
1825                 if (curr_index <= page->index &&
1826                     page->index < curr_index + old_req->num_pages) {
1827                         found = true;
1828                         break;
1829                 }
1830         }
1831         if (!found) {
1832                 list_add(&new_req->writepages_entry, &fi->writepages);
1833                 goto out_unlock;
1834         }
1835
1836         new_req->num_pages = 1;
1837         for (tmp = old_req; tmp != NULL; tmp = tmp->misc.write.next) {
1838                 BUG_ON(tmp->inode != new_req->inode);
1839                 curr_index = tmp->misc.write.in.offset >> PAGE_CACHE_SHIFT;
1840                 if (tmp->num_pages == 1 &&
1841                     curr_index == page->index) {
1842                         old_req = tmp;
1843                 }
1844         }
1845
1846         if (old_req->num_pages == 1 && (old_req->state == FUSE_REQ_INIT ||
1847                                         old_req->state == FUSE_REQ_PENDING)) {
1848                 struct backing_dev_info *bdi = page->mapping->backing_dev_info;
1849
1850                 copy_highpage(old_req->pages[0], page);
1851                 spin_unlock(&fc->lock);
1852
1853                 dec_bdi_stat(bdi, BDI_WRITEBACK);
1854                 dec_zone_page_state(page, NR_WRITEBACK_TEMP);
1855                 bdi_writeout_inc(bdi);
1856                 fuse_writepage_free(fc, new_req);
1857                 fuse_request_free(new_req);
1858                 goto out;
1859         } else {
1860                 new_req->misc.write.next = old_req->misc.write.next;
1861                 old_req->misc.write.next = new_req;
1862         }
1863 out_unlock:
1864         spin_unlock(&fc->lock);
1865 out:
1866         return found;
1867 }
1868
1869 static int fuse_writepages_fill(struct page *page,
1870                 struct writeback_control *wbc, void *_data)
1871 {
1872         struct fuse_fill_wb_data *data = _data;
1873         struct fuse_req *req = data->req;
1874         struct inode *inode = data->inode;
1875         struct fuse_conn *fc = get_fuse_conn(inode);
1876         struct page *tmp_page;
1877         bool is_writeback;
1878         int err;
1879
1880         if (!data->ff) {
1881                 err = -EIO;
1882                 data->ff = fuse_write_file_get(fc, get_fuse_inode(inode));
1883                 if (!data->ff)
1884                         goto out_unlock;
1885         }
1886
1887         /*
1888          * Being under writeback is unlikely but possible.  For example direct
1889          * read to an mmaped fuse file will set the page dirty twice; once when
1890          * the pages are faulted with get_user_pages(), and then after the read
1891          * completed.
1892          */
1893         is_writeback = fuse_page_is_writeback(inode, page->index);
1894
1895         if (req && req->num_pages &&
1896             (is_writeback || req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
1897              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_write ||
1898              data->orig_pages[req->num_pages - 1]->index + 1 != page->index)) {
1899                 fuse_writepages_send(data);
1900                 data->req = NULL;
1901         }
1902         err = -ENOMEM;
1903         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1904         if (!tmp_page)
1905                 goto out_unlock;
1906
1907         /*
1908          * The page must not be redirtied until the writeout is completed
1909          * (i.e. userspace has sent a reply to the write request).  Otherwise
1910          * there could be more than one temporary page instance for each real
1911          * page.
1912          *
1913          * This is ensured by holding the page lock in page_mkwrite() while
1914          * checking fuse_page_is_writeback().  We already hold the page lock
1915          * since clear_page_dirty_for_io() and keep it held until we add the
1916          * request to the fi->writepages list and increment req->num_pages.
1917          * After this fuse_page_is_writeback() will indicate that the page is
1918          * under writeback, so we can release the page lock.
1919          */
1920         if (data->req == NULL) {
1921                 struct fuse_inode *fi = get_fuse_inode(inode);
1922
1923                 err = -ENOMEM;
1924                 req = fuse_request_alloc_nofs(FUSE_MAX_PAGES_PER_REQ);
1925                 if (!req) {
1926                         __free_page(tmp_page);
1927                         goto out_unlock;
1928                 }
1929
1930                 fuse_write_fill(req, data->ff, page_offset(page), 0);
1931                 req->misc.write.in.write_flags |= FUSE_WRITE_CACHE;
1932                 req->misc.write.next = NULL;
1933                 req->in.argpages = 1;
1934                 req->background = 1;
1935                 req->num_pages = 0;
1936                 req->end = fuse_writepage_end;
1937                 req->inode = inode;
1938
1939                 spin_lock(&fc->lock);
1940                 list_add(&req->writepages_entry, &fi->writepages);
1941                 spin_unlock(&fc->lock);
1942
1943                 data->req = req;
1944         }
1945         set_page_writeback(page);
1946
1947         copy_highpage(tmp_page, page);
1948         req->pages[req->num_pages] = tmp_page;
1949         req->page_descs[req->num_pages].offset = 0;
1950         req->page_descs[req->num_pages].length = PAGE_SIZE;
1951
1952         inc_bdi_stat(page->mapping->backing_dev_info, BDI_WRITEBACK);
1953         inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
1954
1955         err = 0;
1956         if (is_writeback && fuse_writepage_in_flight(req, page)) {
1957                 end_page_writeback(page);
1958                 data->req = NULL;
1959                 goto out_unlock;
1960         }
1961         data->orig_pages[req->num_pages] = page;
1962
1963         /*
1964          * Protected by fc->lock against concurrent access by
1965          * fuse_page_is_writeback().
1966          */
1967         spin_lock(&fc->lock);
1968         req->num_pages++;
1969         spin_unlock(&fc->lock);
1970
1971 out_unlock:
1972         unlock_page(page);
1973
1974         return err;
1975 }
1976
1977 static int fuse_writepages(struct address_space *mapping,
1978                            struct writeback_control *wbc)
1979 {
1980         struct inode *inode = mapping->host;
1981         struct fuse_fill_wb_data data;
1982         int err;
1983
1984         err = -EIO;
1985         if (is_bad_inode(inode))
1986                 goto out;
1987
1988         data.inode = inode;
1989         data.req = NULL;
1990         data.ff = NULL;
1991
1992         err = -ENOMEM;
1993         data.orig_pages = kzalloc(sizeof(struct page *) *
1994                                   FUSE_MAX_PAGES_PER_REQ,
1995                                   GFP_NOFS);
1996         if (!data.orig_pages)
1997                 goto out;
1998
1999         err = write_cache_pages(mapping, wbc, fuse_writepages_fill, &data);
2000         if (data.req) {
2001                 /* Ignore errors if we can write at least one page */
2002                 BUG_ON(!data.req->num_pages);
2003                 fuse_writepages_send(&data);
2004                 err = 0;
2005         }
2006         if (data.ff)
2007                 fuse_file_put(data.ff, false);
2008
2009         kfree(data.orig_pages);
2010 out:
2011         return err;
2012 }
2013
2014 /*
2015  * It's worthy to make sure that space is reserved on disk for the write,
2016  * but how to implement it without killing performance need more thinking.
2017  */
2018 static int fuse_write_begin(struct file *file, struct address_space *mapping,
2019                 loff_t pos, unsigned len, unsigned flags,
2020                 struct page **pagep, void **fsdata)
2021 {
2022         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
2023         struct fuse_conn *fc = get_fuse_conn(file->f_dentry->d_inode);
2024         struct page *page;
2025         loff_t fsize;
2026         int err = -ENOMEM;
2027
2028         WARN_ON(!fc->writeback_cache);
2029
2030         page = grab_cache_page_write_begin(mapping, index, flags);
2031         if (!page)
2032                 goto error;
2033
2034         fuse_wait_on_page_writeback(mapping->host, page->index);
2035
2036         if (PageUptodate(page) || len == PAGE_CACHE_SIZE)
2037                 goto success;
2038         /*
2039          * Check if the start this page comes after the end of file, in which
2040          * case the readpage can be optimized away.
2041          */
2042         fsize = i_size_read(mapping->host);
2043         if (fsize <= (pos & PAGE_CACHE_MASK)) {
2044                 size_t off = pos & ~PAGE_CACHE_MASK;
2045                 if (off)
2046                         zero_user_segment(page, 0, off);
2047                 goto success;
2048         }
2049         err = fuse_do_readpage(file, page);
2050         if (err)
2051                 goto cleanup;
2052 success:
2053         *pagep = page;
2054         return 0;
2055
2056 cleanup:
2057         unlock_page(page);
2058         page_cache_release(page);
2059 error:
2060         return err;
2061 }
2062
2063 static int fuse_write_end(struct file *file, struct address_space *mapping,
2064                 loff_t pos, unsigned len, unsigned copied,
2065                 struct page *page, void *fsdata)
2066 {
2067         struct inode *inode = page->mapping->host;
2068
2069         if (!PageUptodate(page)) {
2070                 /* Zero any unwritten bytes at the end of the page */
2071                 size_t endoff = (pos + copied) & ~PAGE_CACHE_MASK;
2072                 if (endoff)
2073                         zero_user_segment(page, endoff, PAGE_CACHE_SIZE);
2074                 SetPageUptodate(page);
2075         }
2076
2077         fuse_write_update_size(inode, pos + copied);
2078         set_page_dirty(page);
2079         unlock_page(page);
2080         page_cache_release(page);
2081
2082         return copied;
2083 }
2084
2085 static int fuse_launder_page(struct page *page)
2086 {
2087         int err = 0;
2088         if (clear_page_dirty_for_io(page)) {
2089                 struct inode *inode = page->mapping->host;
2090                 err = fuse_writepage_locked(page);
2091                 if (!err)
2092                         fuse_wait_on_page_writeback(inode, page->index);
2093         }
2094         return err;
2095 }
2096
2097 /*
2098  * Write back dirty pages now, because there may not be any suitable
2099  * open files later
2100  */
2101 static void fuse_vma_close(struct vm_area_struct *vma)
2102 {
2103         filemap_write_and_wait(vma->vm_file->f_mapping);
2104 }
2105
2106 /*
2107  * Wait for writeback against this page to complete before allowing it
2108  * to be marked dirty again, and hence written back again, possibly
2109  * before the previous writepage completed.
2110  *
2111  * Block here, instead of in ->writepage(), so that the userspace fs
2112  * can only block processes actually operating on the filesystem.
2113  *
2114  * Otherwise unprivileged userspace fs would be able to block
2115  * unrelated:
2116  *
2117  * - page migration
2118  * - sync(2)
2119  * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
2120  */
2121 static int fuse_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
2122 {
2123         struct page *page = vmf->page;
2124         struct inode *inode = file_inode(vma->vm_file);
2125
2126         file_update_time(vma->vm_file);
2127         lock_page(page);
2128         if (page->mapping != inode->i_mapping) {
2129                 unlock_page(page);
2130                 return VM_FAULT_NOPAGE;
2131         }
2132
2133         fuse_wait_on_page_writeback(inode, page->index);
2134         return VM_FAULT_LOCKED;
2135 }
2136
2137 static const struct vm_operations_struct fuse_file_vm_ops = {
2138         .close          = fuse_vma_close,
2139         .fault          = filemap_fault,
2140         .map_pages      = filemap_map_pages,
2141         .page_mkwrite   = fuse_page_mkwrite,
2142         .remap_pages    = generic_file_remap_pages,
2143 };
2144
2145 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
2146 {
2147         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2148                 fuse_link_write_file(file);
2149
2150         file_accessed(file);
2151         vma->vm_ops = &fuse_file_vm_ops;
2152         return 0;
2153 }
2154
2155 static int fuse_direct_mmap(struct file *file, struct vm_area_struct *vma)
2156 {
2157         /* Can't provide the coherency needed for MAP_SHARED */
2158         if (vma->vm_flags & VM_MAYSHARE)
2159                 return -ENODEV;
2160
2161         invalidate_inode_pages2(file->f_mapping);
2162
2163         return generic_file_mmap(file, vma);
2164 }
2165
2166 static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
2167                                   struct file_lock *fl)
2168 {
2169         switch (ffl->type) {
2170         case F_UNLCK:
2171                 break;
2172
2173         case F_RDLCK:
2174         case F_WRLCK:
2175                 if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
2176                     ffl->end < ffl->start)
2177                         return -EIO;
2178
2179                 fl->fl_start = ffl->start;
2180                 fl->fl_end = ffl->end;
2181                 fl->fl_pid = ffl->pid;
2182                 break;
2183
2184         default:
2185                 return -EIO;
2186         }
2187         fl->fl_type = ffl->type;
2188         return 0;
2189 }
2190
2191 static void fuse_lk_fill(struct fuse_req *req, struct file *file,
2192                          const struct file_lock *fl, int opcode, pid_t pid,
2193                          int flock)
2194 {
2195         struct inode *inode = file_inode(file);
2196         struct fuse_conn *fc = get_fuse_conn(inode);
2197         struct fuse_file *ff = file->private_data;
2198         struct fuse_lk_in *arg = &req->misc.lk_in;
2199
2200         arg->fh = ff->fh;
2201         arg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
2202         arg->lk.start = fl->fl_start;
2203         arg->lk.end = fl->fl_end;
2204         arg->lk.type = fl->fl_type;
2205         arg->lk.pid = pid;
2206         if (flock)
2207                 arg->lk_flags |= FUSE_LK_FLOCK;
2208         req->in.h.opcode = opcode;
2209         req->in.h.nodeid = get_node_id(inode);
2210         req->in.numargs = 1;
2211         req->in.args[0].size = sizeof(*arg);
2212         req->in.args[0].value = arg;
2213 }
2214
2215 static int fuse_getlk(struct file *file, struct file_lock *fl)
2216 {
2217         struct inode *inode = file_inode(file);
2218         struct fuse_conn *fc = get_fuse_conn(inode);
2219         struct fuse_req *req;
2220         struct fuse_lk_out outarg;
2221         int err;
2222
2223         req = fuse_get_req_nopages(fc);
2224         if (IS_ERR(req))
2225                 return PTR_ERR(req);
2226
2227         fuse_lk_fill(req, file, fl, FUSE_GETLK, 0, 0);
2228         req->out.numargs = 1;
2229         req->out.args[0].size = sizeof(outarg);
2230         req->out.args[0].value = &outarg;
2231         fuse_request_send(fc, req);
2232         err = req->out.h.error;
2233         fuse_put_request(fc, req);
2234         if (!err)
2235                 err = convert_fuse_file_lock(&outarg.lk, fl);
2236
2237         return err;
2238 }
2239
2240 static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
2241 {
2242         struct inode *inode = file_inode(file);
2243         struct fuse_conn *fc = get_fuse_conn(inode);
2244         struct fuse_req *req;
2245         int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
2246         pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
2247         int err;
2248
2249         if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
2250                 /* NLM needs asynchronous locks, which we don't support yet */
2251                 return -ENOLCK;
2252         }
2253
2254         /* Unlock on close is handled by the flush method */
2255         if (fl->fl_flags & FL_CLOSE)
2256                 return 0;
2257
2258         req = fuse_get_req_nopages(fc);
2259         if (IS_ERR(req))
2260                 return PTR_ERR(req);
2261
2262         fuse_lk_fill(req, file, fl, opcode, pid, flock);
2263         fuse_request_send(fc, req);
2264         err = req->out.h.error;
2265         /* locking is restartable */
2266         if (err == -EINTR)
2267                 err = -ERESTARTSYS;
2268         fuse_put_request(fc, req);
2269         return err;
2270 }
2271
2272 static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
2273 {
2274         struct inode *inode = file_inode(file);
2275         struct fuse_conn *fc = get_fuse_conn(inode);
2276         int err;
2277
2278         if (cmd == F_CANCELLK) {
2279                 err = 0;
2280         } else if (cmd == F_GETLK) {
2281                 if (fc->no_lock) {
2282                         posix_test_lock(file, fl);
2283                         err = 0;
2284                 } else
2285                         err = fuse_getlk(file, fl);
2286         } else {
2287                 if (fc->no_lock)
2288                         err = posix_lock_file(file, fl, NULL);
2289                 else
2290                         err = fuse_setlk(file, fl, 0);
2291         }
2292         return err;
2293 }
2294
2295 static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
2296 {
2297         struct inode *inode = file_inode(file);
2298         struct fuse_conn *fc = get_fuse_conn(inode);
2299         int err;
2300
2301         if (fc->no_flock) {
2302                 err = flock_lock_file_wait(file, fl);
2303         } else {
2304                 struct fuse_file *ff = file->private_data;
2305
2306                 /* emulate flock with POSIX locks */
2307                 fl->fl_owner = (fl_owner_t) file;
2308                 ff->flock = true;
2309                 err = fuse_setlk(file, fl, 1);
2310         }
2311
2312         return err;
2313 }
2314
2315 static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
2316 {
2317         struct inode *inode = mapping->host;
2318         struct fuse_conn *fc = get_fuse_conn(inode);
2319         struct fuse_req *req;
2320         struct fuse_bmap_in inarg;
2321         struct fuse_bmap_out outarg;
2322         int err;
2323
2324         if (!inode->i_sb->s_bdev || fc->no_bmap)
2325                 return 0;
2326
2327         req = fuse_get_req_nopages(fc);
2328         if (IS_ERR(req))
2329                 return 0;
2330
2331         memset(&inarg, 0, sizeof(inarg));
2332         inarg.block = block;
2333         inarg.blocksize = inode->i_sb->s_blocksize;
2334         req->in.h.opcode = FUSE_BMAP;
2335         req->in.h.nodeid = get_node_id(inode);
2336         req->in.numargs = 1;
2337         req->in.args[0].size = sizeof(inarg);
2338         req->in.args[0].value = &inarg;
2339         req->out.numargs = 1;
2340         req->out.args[0].size = sizeof(outarg);
2341         req->out.args[0].value = &outarg;
2342         fuse_request_send(fc, req);
2343         err = req->out.h.error;
2344         fuse_put_request(fc, req);
2345         if (err == -ENOSYS)
2346                 fc->no_bmap = 1;
2347
2348         return err ? 0 : outarg.block;
2349 }
2350
2351 static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
2352 {
2353         loff_t retval;
2354         struct inode *inode = file_inode(file);
2355
2356         /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
2357         if (whence == SEEK_CUR || whence == SEEK_SET)
2358                 return generic_file_llseek(file, offset, whence);
2359
2360         mutex_lock(&inode->i_mutex);
2361         retval = fuse_update_attributes(inode, NULL, file, NULL);
2362         if (!retval)
2363                 retval = generic_file_llseek(file, offset, whence);
2364         mutex_unlock(&inode->i_mutex);
2365
2366         return retval;
2367 }
2368
2369 static int fuse_ioctl_copy_user(struct page **pages, struct iovec *iov,
2370                         unsigned int nr_segs, size_t bytes, bool to_user)
2371 {
2372         struct iov_iter ii;
2373         int page_idx = 0;
2374
2375         if (!bytes)
2376                 return 0;
2377
2378         iov_iter_init(&ii, iov, nr_segs, bytes, 0);
2379
2380         while (iov_iter_count(&ii)) {
2381                 struct page *page = pages[page_idx++];
2382                 size_t todo = min_t(size_t, PAGE_SIZE, iov_iter_count(&ii));
2383                 void *kaddr;
2384
2385                 kaddr = kmap(page);
2386
2387                 while (todo) {
2388                         char __user *uaddr = ii.iov->iov_base + ii.iov_offset;
2389                         size_t iov_len = ii.iov->iov_len - ii.iov_offset;
2390                         size_t copy = min(todo, iov_len);
2391                         size_t left;
2392
2393                         if (!to_user)
2394                                 left = copy_from_user(kaddr, uaddr, copy);
2395                         else
2396                                 left = copy_to_user(uaddr, kaddr, copy);
2397
2398                         if (unlikely(left))
2399                                 return -EFAULT;
2400
2401                         iov_iter_advance(&ii, copy);
2402                         todo -= copy;
2403                         kaddr += copy;
2404                 }
2405
2406                 kunmap(page);
2407         }
2408
2409         return 0;
2410 }
2411
2412 /*
2413  * CUSE servers compiled on 32bit broke on 64bit kernels because the
2414  * ABI was defined to be 'struct iovec' which is different on 32bit
2415  * and 64bit.  Fortunately we can determine which structure the server
2416  * used from the size of the reply.
2417  */
2418 static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
2419                                      size_t transferred, unsigned count,
2420                                      bool is_compat)
2421 {
2422 #ifdef CONFIG_COMPAT
2423         if (count * sizeof(struct compat_iovec) == transferred) {
2424                 struct compat_iovec *ciov = src;
2425                 unsigned i;
2426
2427                 /*
2428                  * With this interface a 32bit server cannot support
2429                  * non-compat (i.e. ones coming from 64bit apps) ioctl
2430                  * requests
2431                  */
2432                 if (!is_compat)
2433                         return -EINVAL;
2434
2435                 for (i = 0; i < count; i++) {
2436                         dst[i].iov_base = compat_ptr(ciov[i].iov_base);
2437                         dst[i].iov_len = ciov[i].iov_len;
2438                 }
2439                 return 0;
2440         }
2441 #endif
2442
2443         if (count * sizeof(struct iovec) != transferred)
2444                 return -EIO;
2445
2446         memcpy(dst, src, transferred);
2447         return 0;
2448 }
2449
2450 /* Make sure iov_length() won't overflow */
2451 static int fuse_verify_ioctl_iov(struct iovec *iov, size_t count)
2452 {
2453         size_t n;
2454         u32 max = FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT;
2455
2456         for (n = 0; n < count; n++, iov++) {
2457                 if (iov->iov_len > (size_t) max)
2458                         return -ENOMEM;
2459                 max -= iov->iov_len;
2460         }
2461         return 0;
2462 }
2463
2464 static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
2465                                  void *src, size_t transferred, unsigned count,
2466                                  bool is_compat)
2467 {
2468         unsigned i;
2469         struct fuse_ioctl_iovec *fiov = src;
2470
2471         if (fc->minor < 16) {
2472                 return fuse_copy_ioctl_iovec_old(dst, src, transferred,
2473                                                  count, is_compat);
2474         }
2475
2476         if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
2477                 return -EIO;
2478
2479         for (i = 0; i < count; i++) {
2480                 /* Did the server supply an inappropriate value? */
2481                 if (fiov[i].base != (unsigned long) fiov[i].base ||
2482                     fiov[i].len != (unsigned long) fiov[i].len)
2483                         return -EIO;
2484
2485                 dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
2486                 dst[i].iov_len = (size_t) fiov[i].len;
2487
2488 #ifdef CONFIG_COMPAT
2489                 if (is_compat &&
2490                     (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
2491                      (compat_size_t) dst[i].iov_len != fiov[i].len))
2492                         return -EIO;
2493 #endif
2494         }
2495
2496         return 0;
2497 }
2498
2499
2500 /*
2501  * For ioctls, there is no generic way to determine how much memory
2502  * needs to be read and/or written.  Furthermore, ioctls are allowed
2503  * to dereference the passed pointer, so the parameter requires deep
2504  * copying but FUSE has no idea whatsoever about what to copy in or
2505  * out.
2506  *
2507  * This is solved by allowing FUSE server to retry ioctl with
2508  * necessary in/out iovecs.  Let's assume the ioctl implementation
2509  * needs to read in the following structure.
2510  *
2511  * struct a {
2512  *      char    *buf;
2513  *      size_t  buflen;
2514  * }
2515  *
2516  * On the first callout to FUSE server, inarg->in_size and
2517  * inarg->out_size will be NULL; then, the server completes the ioctl
2518  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
2519  * the actual iov array to
2520  *
2521  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
2522  *
2523  * which tells FUSE to copy in the requested area and retry the ioctl.
2524  * On the second round, the server has access to the structure and
2525  * from that it can tell what to look for next, so on the invocation,
2526  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
2527  *
2528  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
2529  *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
2530  *
2531  * FUSE will copy both struct a and the pointed buffer from the
2532  * process doing the ioctl and retry ioctl with both struct a and the
2533  * buffer.
2534  *
2535  * This time, FUSE server has everything it needs and completes ioctl
2536  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
2537  *
2538  * Copying data out works the same way.
2539  *
2540  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
2541  * automatically initializes in and out iovs by decoding @cmd with
2542  * _IOC_* macros and the server is not allowed to request RETRY.  This
2543  * limits ioctl data transfers to well-formed ioctls and is the forced
2544  * behavior for all FUSE servers.
2545  */
2546 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
2547                    unsigned int flags)
2548 {
2549         struct fuse_file *ff = file->private_data;
2550         struct fuse_conn *fc = ff->fc;
2551         struct fuse_ioctl_in inarg = {
2552                 .fh = ff->fh,
2553                 .cmd = cmd,
2554                 .arg = arg,
2555                 .flags = flags
2556         };
2557         struct fuse_ioctl_out outarg;
2558         struct fuse_req *req = NULL;
2559         struct page **pages = NULL;
2560         struct iovec *iov_page = NULL;
2561         struct iovec *in_iov = NULL, *out_iov = NULL;
2562         unsigned int in_iovs = 0, out_iovs = 0, num_pages = 0, max_pages;
2563         size_t in_size, out_size, transferred;
2564         int err;
2565
2566 #if BITS_PER_LONG == 32
2567         inarg.flags |= FUSE_IOCTL_32BIT;
2568 #else
2569         if (flags & FUSE_IOCTL_COMPAT)
2570                 inarg.flags |= FUSE_IOCTL_32BIT;
2571 #endif
2572
2573         /* assume all the iovs returned by client always fits in a page */
2574         BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
2575
2576         err = -ENOMEM;
2577         pages = kcalloc(FUSE_MAX_PAGES_PER_REQ, sizeof(pages[0]), GFP_KERNEL);
2578         iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
2579         if (!pages || !iov_page)
2580                 goto out;
2581
2582         /*
2583          * If restricted, initialize IO parameters as encoded in @cmd.
2584          * RETRY from server is not allowed.
2585          */
2586         if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
2587                 struct iovec *iov = iov_page;
2588
2589                 iov->iov_base = (void __user *)arg;
2590                 iov->iov_len = _IOC_SIZE(cmd);
2591
2592                 if (_IOC_DIR(cmd) & _IOC_WRITE) {
2593                         in_iov = iov;
2594                         in_iovs = 1;
2595                 }
2596
2597                 if (_IOC_DIR(cmd) & _IOC_READ) {
2598                         out_iov = iov;
2599                         out_iovs = 1;
2600                 }
2601         }
2602
2603  retry:
2604         inarg.in_size = in_size = iov_length(in_iov, in_iovs);
2605         inarg.out_size = out_size = iov_length(out_iov, out_iovs);
2606
2607         /*
2608          * Out data can be used either for actual out data or iovs,
2609          * make sure there always is at least one page.
2610          */
2611         out_size = max_t(size_t, out_size, PAGE_SIZE);
2612         max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
2613
2614         /* make sure there are enough buffer pages and init request with them */
2615         err = -ENOMEM;
2616         if (max_pages > FUSE_MAX_PAGES_PER_REQ)
2617                 goto out;
2618         while (num_pages < max_pages) {
2619                 pages[num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
2620                 if (!pages[num_pages])
2621                         goto out;
2622                 num_pages++;
2623         }
2624
2625         req = fuse_get_req(fc, num_pages);
2626         if (IS_ERR(req)) {
2627                 err = PTR_ERR(req);
2628                 req = NULL;
2629                 goto out;
2630         }
2631         memcpy(req->pages, pages, sizeof(req->pages[0]) * num_pages);
2632         req->num_pages = num_pages;
2633         fuse_page_descs_length_init(req, 0, req->num_pages);
2634
2635         /* okay, let's send it to the client */
2636         req->in.h.opcode = FUSE_IOCTL;
2637         req->in.h.nodeid = ff->nodeid;
2638         req->in.numargs = 1;
2639         req->in.args[0].size = sizeof(inarg);
2640         req->in.args[0].value = &inarg;
2641         if (in_size) {
2642                 req->in.numargs++;
2643                 req->in.args[1].size = in_size;
2644                 req->in.argpages = 1;
2645
2646                 err = fuse_ioctl_copy_user(pages, in_iov, in_iovs, in_size,
2647                                            false);
2648                 if (err)
2649                         goto out;
2650         }
2651
2652         req->out.numargs = 2;
2653         req->out.args[0].size = sizeof(outarg);
2654         req->out.args[0].value = &outarg;
2655         req->out.args[1].size = out_size;
2656         req->out.argpages = 1;
2657         req->out.argvar = 1;
2658
2659         fuse_request_send(fc, req);
2660         err = req->out.h.error;
2661         transferred = req->out.args[1].size;
2662         fuse_put_request(fc, req);
2663         req = NULL;
2664         if (err)
2665                 goto out;
2666
2667         /* did it ask for retry? */
2668         if (outarg.flags & FUSE_IOCTL_RETRY) {
2669                 void *vaddr;
2670
2671                 /* no retry if in restricted mode */
2672                 err = -EIO;
2673                 if (!(flags & FUSE_IOCTL_UNRESTRICTED))
2674                         goto out;
2675
2676                 in_iovs = outarg.in_iovs;
2677                 out_iovs = outarg.out_iovs;
2678
2679                 /*
2680                  * Make sure things are in boundary, separate checks
2681                  * are to protect against overflow.
2682                  */
2683                 err = -ENOMEM;
2684                 if (in_iovs > FUSE_IOCTL_MAX_IOV ||
2685                     out_iovs > FUSE_IOCTL_MAX_IOV ||
2686                     in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
2687                         goto out;
2688
2689                 vaddr = kmap_atomic(pages[0]);
2690                 err = fuse_copy_ioctl_iovec(fc, iov_page, vaddr,
2691                                             transferred, in_iovs + out_iovs,
2692                                             (flags & FUSE_IOCTL_COMPAT) != 0);
2693                 kunmap_atomic(vaddr);
2694                 if (err)
2695                         goto out;
2696
2697                 in_iov = iov_page;
2698                 out_iov = in_iov + in_iovs;
2699
2700                 err = fuse_verify_ioctl_iov(in_iov, in_iovs);
2701                 if (err)
2702                         goto out;
2703
2704                 err = fuse_verify_ioctl_iov(out_iov, out_iovs);
2705                 if (err)
2706                         goto out;
2707
2708                 goto retry;
2709         }
2710
2711         err = -EIO;
2712         if (transferred > inarg.out_size)
2713                 goto out;
2714
2715         err = fuse_ioctl_copy_user(pages, out_iov, out_iovs, transferred, true);
2716  out:
2717         if (req)
2718                 fuse_put_request(fc, req);
2719         free_page((unsigned long) iov_page);
2720         while (num_pages)
2721                 __free_page(pages[--num_pages]);
2722         kfree(pages);
2723
2724         return err ? err : outarg.result;
2725 }
2726 EXPORT_SYMBOL_GPL(fuse_do_ioctl);
2727
2728 long fuse_ioctl_common(struct file *file, unsigned int cmd,
2729                        unsigned long arg, unsigned int flags)
2730 {
2731         struct inode *inode = file_inode(file);
2732         struct fuse_conn *fc = get_fuse_conn(inode);
2733
2734         if (!fuse_allow_current_process(fc))
2735                 return -EACCES;
2736
2737         if (is_bad_inode(inode))
2738                 return -EIO;
2739
2740         return fuse_do_ioctl(file, cmd, arg, flags);
2741 }
2742
2743 static long fuse_file_ioctl(struct file *file, unsigned int cmd,
2744                             unsigned long arg)
2745 {
2746         return fuse_ioctl_common(file, cmd, arg, 0);
2747 }
2748
2749 static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
2750                                    unsigned long arg)
2751 {
2752         return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
2753 }
2754
2755 /*
2756  * All files which have been polled are linked to RB tree
2757  * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
2758  * find the matching one.
2759  */
2760 static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
2761                                               struct rb_node **parent_out)
2762 {
2763         struct rb_node **link = &fc->polled_files.rb_node;
2764         struct rb_node *last = NULL;
2765
2766         while (*link) {
2767                 struct fuse_file *ff;
2768
2769                 last = *link;
2770                 ff = rb_entry(last, struct fuse_file, polled_node);
2771
2772                 if (kh < ff->kh)
2773                         link = &last->rb_left;
2774                 else if (kh > ff->kh)
2775                         link = &last->rb_right;
2776                 else
2777                         return link;
2778         }
2779
2780         if (parent_out)
2781                 *parent_out = last;
2782         return link;
2783 }
2784
2785 /*
2786  * The file is about to be polled.  Make sure it's on the polled_files
2787  * RB tree.  Note that files once added to the polled_files tree are
2788  * not removed before the file is released.  This is because a file
2789  * polled once is likely to be polled again.
2790  */
2791 static void fuse_register_polled_file(struct fuse_conn *fc,
2792                                       struct fuse_file *ff)
2793 {
2794         spin_lock(&fc->lock);
2795         if (RB_EMPTY_NODE(&ff->polled_node)) {
2796                 struct rb_node **link, *uninitialized_var(parent);
2797
2798                 link = fuse_find_polled_node(fc, ff->kh, &parent);
2799                 BUG_ON(*link);
2800                 rb_link_node(&ff->polled_node, parent, link);
2801                 rb_insert_color(&ff->polled_node, &fc->polled_files);
2802         }
2803         spin_unlock(&fc->lock);
2804 }
2805
2806 unsigned fuse_file_poll(struct file *file, poll_table *wait)
2807 {
2808         struct fuse_file *ff = file->private_data;
2809         struct fuse_conn *fc = ff->fc;
2810         struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
2811         struct fuse_poll_out outarg;
2812         struct fuse_req *req;
2813         int err;
2814
2815         if (fc->no_poll)
2816                 return DEFAULT_POLLMASK;
2817
2818         poll_wait(file, &ff->poll_wait, wait);
2819         inarg.events = (__u32)poll_requested_events(wait);
2820
2821         /*
2822          * Ask for notification iff there's someone waiting for it.
2823          * The client may ignore the flag and always notify.
2824          */
2825         if (waitqueue_active(&ff->poll_wait)) {
2826                 inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
2827                 fuse_register_polled_file(fc, ff);
2828         }
2829
2830         req = fuse_get_req_nopages(fc);
2831         if (IS_ERR(req))
2832                 return POLLERR;
2833
2834         req->in.h.opcode = FUSE_POLL;
2835         req->in.h.nodeid = ff->nodeid;
2836         req->in.numargs = 1;
2837         req->in.args[0].size = sizeof(inarg);
2838         req->in.args[0].value = &inarg;
2839         req->out.numargs = 1;
2840         req->out.args[0].size = sizeof(outarg);
2841         req->out.args[0].value = &outarg;
2842         fuse_request_send(fc, req);
2843         err = req->out.h.error;
2844         fuse_put_request(fc, req);
2845
2846         if (!err)
2847                 return outarg.revents;
2848         if (err == -ENOSYS) {
2849                 fc->no_poll = 1;
2850                 return DEFAULT_POLLMASK;
2851         }
2852         return POLLERR;
2853 }
2854 EXPORT_SYMBOL_GPL(fuse_file_poll);
2855
2856 /*
2857  * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
2858  * wakes up the poll waiters.
2859  */
2860 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
2861                             struct fuse_notify_poll_wakeup_out *outarg)
2862 {
2863         u64 kh = outarg->kh;
2864         struct rb_node **link;
2865
2866         spin_lock(&fc->lock);
2867
2868         link = fuse_find_polled_node(fc, kh, NULL);
2869         if (*link) {
2870                 struct fuse_file *ff;
2871
2872                 ff = rb_entry(*link, struct fuse_file, polled_node);
2873                 wake_up_interruptible_sync(&ff->poll_wait);
2874         }
2875
2876         spin_unlock(&fc->lock);
2877         return 0;
2878 }
2879
2880 static void fuse_do_truncate(struct file *file)
2881 {
2882         struct inode *inode = file->f_mapping->host;
2883         struct iattr attr;
2884
2885         attr.ia_valid = ATTR_SIZE;
2886         attr.ia_size = i_size_read(inode);
2887
2888         attr.ia_file = file;
2889         attr.ia_valid |= ATTR_FILE;
2890
2891         fuse_do_setattr(inode, &attr, file);
2892 }
2893
2894 static inline loff_t fuse_round_up(loff_t off)
2895 {
2896         return round_up(off, FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
2897 }
2898
2899 static ssize_t
2900 fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2901                         loff_t offset, unsigned long nr_segs)
2902 {
2903         ssize_t ret = 0;
2904         struct file *file = iocb->ki_filp;
2905         struct fuse_file *ff = file->private_data;
2906         bool async_dio = ff->fc->async_dio;
2907         loff_t pos = 0;
2908         struct inode *inode;
2909         loff_t i_size;
2910         size_t count = iov_length(iov, nr_segs);
2911         struct fuse_io_priv *io;
2912
2913         pos = offset;
2914         inode = file->f_mapping->host;
2915         i_size = i_size_read(inode);
2916
2917         if ((rw == READ) && (offset > i_size))
2918                 return 0;
2919
2920         /* optimization for short read */
2921         if (async_dio && rw != WRITE && offset + count > i_size) {
2922                 if (offset >= i_size)
2923                         return 0;
2924                 count = min_t(loff_t, count, fuse_round_up(i_size - offset));
2925         }
2926
2927         io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
2928         if (!io)
2929                 return -ENOMEM;
2930         spin_lock_init(&io->lock);
2931         io->reqs = 1;
2932         io->bytes = -1;
2933         io->size = 0;
2934         io->offset = offset;
2935         io->write = (rw == WRITE);
2936         io->err = 0;
2937         io->file = file;
2938         /*
2939          * By default, we want to optimize all I/Os with async request
2940          * submission to the client filesystem if supported.
2941          */
2942         io->async = async_dio;
2943         io->iocb = iocb;
2944
2945         /*
2946          * We cannot asynchronously extend the size of a file. We have no method
2947          * to wait on real async I/O requests, so we must submit this request
2948          * synchronously.
2949          */
2950         if (!is_sync_kiocb(iocb) && (offset + count > i_size) && rw == WRITE)
2951                 io->async = false;
2952
2953         if (rw == WRITE)
2954                 ret = __fuse_direct_write(io, iov, nr_segs, &pos);
2955         else
2956                 ret = __fuse_direct_read(io, iov, nr_segs, &pos, count);
2957
2958         if (io->async) {
2959                 fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
2960
2961                 /* we have a non-extending, async request, so return */
2962                 if (!is_sync_kiocb(iocb))
2963                         return -EIOCBQUEUED;
2964
2965                 ret = wait_on_sync_kiocb(iocb);
2966         } else {
2967                 kfree(io);
2968         }
2969
2970         if (rw == WRITE) {
2971                 if (ret > 0)
2972                         fuse_write_update_size(inode, pos);
2973                 else if (ret < 0 && offset + count > i_size)
2974                         fuse_do_truncate(file);
2975         }
2976
2977         return ret;
2978 }
2979
2980 static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
2981                                 loff_t length)
2982 {
2983         struct fuse_file *ff = file->private_data;
2984         struct inode *inode = file->f_inode;
2985         struct fuse_inode *fi = get_fuse_inode(inode);
2986         struct fuse_conn *fc = ff->fc;
2987         struct fuse_req *req;
2988         struct fuse_fallocate_in inarg = {
2989                 .fh = ff->fh,
2990                 .offset = offset,
2991                 .length = length,
2992                 .mode = mode
2993         };
2994         int err;
2995         bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) ||
2996                            (mode & FALLOC_FL_PUNCH_HOLE);
2997
2998         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2999                 return -EOPNOTSUPP;
3000
3001         if (fc->no_fallocate)
3002                 return -EOPNOTSUPP;
3003
3004         if (lock_inode) {
3005                 mutex_lock(&inode->i_mutex);
3006                 if (mode & FALLOC_FL_PUNCH_HOLE) {
3007                         loff_t endbyte = offset + length - 1;
3008                         err = filemap_write_and_wait_range(inode->i_mapping,
3009                                                            offset, endbyte);
3010                         if (err)
3011                                 goto out;
3012
3013                         fuse_sync_writes(inode);
3014                 }
3015         }
3016
3017         if (!(mode & FALLOC_FL_KEEP_SIZE))
3018                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3019
3020         req = fuse_get_req_nopages(fc);
3021         if (IS_ERR(req)) {
3022                 err = PTR_ERR(req);
3023                 goto out;
3024         }
3025
3026         req->in.h.opcode = FUSE_FALLOCATE;
3027         req->in.h.nodeid = ff->nodeid;
3028         req->in.numargs = 1;
3029         req->in.args[0].size = sizeof(inarg);
3030         req->in.args[0].value = &inarg;
3031         fuse_request_send(fc, req);
3032         err = req->out.h.error;
3033         if (err == -ENOSYS) {
3034                 fc->no_fallocate = 1;
3035                 err = -EOPNOTSUPP;
3036         }
3037         fuse_put_request(fc, req);
3038
3039         if (err)
3040                 goto out;
3041
3042         /* we could have extended the file */
3043         if (!(mode & FALLOC_FL_KEEP_SIZE)) {
3044                 bool changed = fuse_write_update_size(inode, offset + length);
3045
3046                 if (changed && fc->writeback_cache)
3047                         file_update_time(file);
3048         }
3049
3050         if (mode & FALLOC_FL_PUNCH_HOLE)
3051                 truncate_pagecache_range(inode, offset, offset + length - 1);
3052
3053         fuse_invalidate_attr(inode);
3054
3055 out:
3056         if (!(mode & FALLOC_FL_KEEP_SIZE))
3057                 clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3058
3059         if (lock_inode)
3060                 mutex_unlock(&inode->i_mutex);
3061
3062         return err;
3063 }
3064
3065 static const struct file_operations fuse_file_operations = {
3066         .llseek         = fuse_file_llseek,
3067         .read           = do_sync_read,
3068         .aio_read       = fuse_file_aio_read,
3069         .write          = do_sync_write,
3070         .aio_write      = fuse_file_aio_write,
3071         .mmap           = fuse_file_mmap,
3072         .open           = fuse_open,
3073         .flush          = fuse_flush,
3074         .release        = fuse_release,
3075         .fsync          = fuse_fsync,
3076         .lock           = fuse_file_lock,
3077         .flock          = fuse_file_flock,
3078         .splice_read    = generic_file_splice_read,
3079         .unlocked_ioctl = fuse_file_ioctl,
3080         .compat_ioctl   = fuse_file_compat_ioctl,
3081         .poll           = fuse_file_poll,
3082         .fallocate      = fuse_file_fallocate,
3083 };
3084
3085 static const struct file_operations fuse_direct_io_file_operations = {
3086         .llseek         = fuse_file_llseek,
3087         .read           = fuse_direct_read,
3088         .write          = fuse_direct_write,
3089         .mmap           = fuse_direct_mmap,
3090         .open           = fuse_open,
3091         .flush          = fuse_flush,
3092         .release        = fuse_release,
3093         .fsync          = fuse_fsync,
3094         .lock           = fuse_file_lock,
3095         .flock          = fuse_file_flock,
3096         .unlocked_ioctl = fuse_file_ioctl,
3097         .compat_ioctl   = fuse_file_compat_ioctl,
3098         .poll           = fuse_file_poll,
3099         .fallocate      = fuse_file_fallocate,
3100         /* no splice_read */
3101 };
3102
3103 static const struct address_space_operations fuse_file_aops  = {
3104         .readpage       = fuse_readpage,
3105         .writepage      = fuse_writepage,
3106         .writepages     = fuse_writepages,
3107         .launder_page   = fuse_launder_page,
3108         .readpages      = fuse_readpages,
3109         .set_page_dirty = __set_page_dirty_nobuffers,
3110         .bmap           = fuse_bmap,
3111         .direct_IO      = fuse_direct_IO,
3112         .write_begin    = fuse_write_begin,
3113         .write_end      = fuse_write_end,
3114 };
3115
3116 void fuse_init_file_inode(struct inode *inode)
3117 {
3118         inode->i_fop = &fuse_file_operations;
3119         inode->i_data.a_ops = &fuse_file_aops;
3120 }