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/sched/signal.h>
  16 #include <linux/module.h>
  17 #include <linux/compat.h>
  18 #include <linux/swap.h>
  19 #include <linux/falloc.h>
  20 #include <linux/uio.h>
  21
  22 static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
  23                           int opcode, struct fuse_open_out *outargp)
  24 {
  25         struct fuse_open_in inarg;
  26         FUSE_ARGS(args);
  27
  28         memset(&inarg, 0, sizeof(inarg));
  29         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
  30         if (!fc->atomic_o_trunc)
  31                 inarg.flags &= ~O_TRUNC;
  32         args.in.h.opcode = opcode;
  33         args.in.h.nodeid = nodeid;
  34         args.in.numargs = 1;
  35         args.in.args[0].size = sizeof(inarg);
  36         args.in.args[0].value = &inarg;
  37         args.out.numargs = 1;
  38         args.out.args[0].size = sizeof(*outargp);
  39         args.out.args[0].value = outargp;
  40
  41         return fuse_simple_request(fc, &args);
  42 }
  43
  44 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
  45 {
  46         struct fuse_file *ff;
  47
  48         ff = kzalloc(sizeof(struct fuse_file), GFP_KERNEL);
  49         if (unlikely(!ff))
  50                 return NULL;
  51
  52         ff->fc = fc;
  53         ff->reserved_req = fuse_request_alloc(0);
  54         if (unlikely(!ff->reserved_req)) {
  55                 kfree(ff);
  56                 return NULL;
  57         }
  58
  59         INIT_LIST_HEAD(&ff->write_entry);
  60         mutex_init(&ff->readdir.lock);
  61         refcount_set(&ff->count, 1);
  62         RB_CLEAR_NODE(&ff->polled_node);
  63         init_waitqueue_head(&ff->poll_wait);
  64
  65         ff->kh = atomic64_inc_return(&fc->khctr);
  66
  67         return ff;
  68 }
  69
  70 void fuse_file_free(struct fuse_file *ff)
  71 {
  72         fuse_request_free(ff->reserved_req);
  73         mutex_destroy(&ff->readdir.lock);
  74         kfree(ff);
  75 }
  76
  77 static struct fuse_file *fuse_file_get(struct fuse_file *ff)
  78 {
  79         refcount_inc(&ff->count);
  80         return ff;
  81 }
  82
  83 static void fuse_release_end(struct fuse_conn *fc, struct fuse_req *req)
  84 {
  85         iput(req->misc.release.inode);
  86 }
  87
  88 static void fuse_file_put(struct fuse_file *ff, bool sync, bool isdir)
  89 {
  90         if (refcount_dec_and_test(&ff->count)) {
  91                 struct fuse_req *req = ff->reserved_req;
  92
  93                 if (ff->fc->no_open && !isdir) {
  94                         /*
  95                          * Drop the release request when client does not
  96                          * implement 'open'
  97                          */
  98                         __clear_bit(FR_BACKGROUND, &req->flags);
  99                         iput(req->misc.release.inode);
 100                         fuse_put_request(ff->fc, req);
 101                 } else if (sync) {
 102                         __set_bit(FR_FORCE, &req->flags);
 103                         __clear_bit(FR_BACKGROUND, &req->flags);
 104                         fuse_request_send(ff->fc, req);
 105                         iput(req->misc.release.inode);
 106                         fuse_put_request(ff->fc, req);
 107                 } else {
 108                         req->end = fuse_release_end;
 109                         __set_bit(FR_BACKGROUND, &req->flags);
 110                         fuse_request_send_background(ff->fc, req);
 111                 }
 112                 kfree(ff);
 113         }
 114 }
 115
 116 int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 117                  bool isdir)
 118 {
 119         struct fuse_file *ff;
 120         int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
 121
 122         ff = fuse_file_alloc(fc);
 123         if (!ff)
 124                 return -ENOMEM;
 125
 126         ff->fh = 0;
 127         ff->open_flags = FOPEN_KEEP_CACHE; /* Default for no-open */
 128         if (!fc->no_open || isdir) {
 129                 struct fuse_open_out outarg;
 130                 int err;
 131
 132                 err = fuse_send_open(fc, nodeid, file, opcode, &outarg);
 133                 if (!err) {
 134                         ff->fh = outarg.fh;
 135                         ff->open_flags = outarg.open_flags;
 136
 137                 } else if (err != -ENOSYS || isdir) {
 138                         fuse_file_free(ff);
 139                         return err;
 140                 } else {
 141                         fc->no_open = 1;
 142                 }
 143         }
 144
 145         if (isdir)
 146                 ff->open_flags &= ~FOPEN_DIRECT_IO;
 147
 148         ff->nodeid = nodeid;
 149         file->private_data = ff;
 150
 151         return 0;
 152 }
 153 EXPORT_SYMBOL_GPL(fuse_do_open);
 154
 155 static void fuse_link_write_file(struct file *file)
 156 {
 157         struct inode *inode = file_inode(file);
 158         struct fuse_inode *fi = get_fuse_inode(inode);
 159         struct fuse_file *ff = file->private_data;
 160         /*
 161          * file may be written through mmap, so chain it onto the
 162          * inodes's write_file list
 163          */
 164         spin_lock(&fi->lock);
 165         if (list_empty(&ff->write_entry))
 166                 list_add(&ff->write_entry, &fi->write_files);
 167         spin_unlock(&fi->lock);
 168 }
 169
 170 void fuse_finish_open(struct inode *inode, struct file *file)
 171 {
 172         struct fuse_file *ff = file->private_data;
 173         struct fuse_conn *fc = get_fuse_conn(inode);
 174
 175         if (!(ff->open_flags & FOPEN_KEEP_CACHE))
 176                 invalidate_inode_pages2(inode->i_mapping);
 177         if (ff->open_flags & FOPEN_NONSEEKABLE)
 178                 nonseekable_open(inode, file);
 179         if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {
 180                 struct fuse_inode *fi = get_fuse_inode(inode);
 181
 182                 spin_lock(&fi->lock);
 183                 fi->attr_version = atomic64_inc_return(&fc->attr_version);
 184                 i_size_write(inode, 0);
 185                 spin_unlock(&fi->lock);
 186                 fuse_invalidate_attr(inode);
 187                 if (fc->writeback_cache)
 188                         file_update_time(file);
 189         }
 190         if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)
 191                 fuse_link_write_file(file);
 192 }
 193
 194 int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
 195 {
 196         struct fuse_conn *fc = get_fuse_conn(inode);
 197         int err;
 198         bool lock_inode = (file->f_flags & O_TRUNC) &&
 199                           fc->atomic_o_trunc &&
 200                           fc->writeback_cache;
 201
 202         err = generic_file_open(inode, file);
 203         if (err)
 204                 return err;
 205
 206         if (lock_inode)
 207                 inode_lock(inode);
 208
 209         err = fuse_do_open(fc, get_node_id(inode), file, isdir);
 210
 211         if (!err)
 212                 fuse_finish_open(inode, file);
 213
 214         if (lock_inode)
 215                 inode_unlock(inode);
 216
 217         return err;
 218 }
 219
 220 static void fuse_prepare_release(struct fuse_inode *fi, struct fuse_file *ff,
 221                                  int flags, int opcode)
 222 {
 223         struct fuse_conn *fc = ff->fc;
 224         struct fuse_req *req = ff->reserved_req;
 225         struct fuse_release_in *inarg = &req->misc.release.in;
 226
 227         /* Inode is NULL on error path of fuse_create_open() */
 228         if (likely(fi)) {
 229                 spin_lock(&fi->lock);
 230                 list_del(&ff->write_entry);
 231                 spin_unlock(&fi->lock);
 232         }
 233         spin_lock(&fc->lock);
 234         if (!RB_EMPTY_NODE(&ff->polled_node))
 235                 rb_erase(&ff->polled_node, &fc->polled_files);
 236         spin_unlock(&fc->lock);
 237
 238         wake_up_interruptible_all(&ff->poll_wait);
 239
 240         inarg->fh = ff->fh;
 241         inarg->flags = flags;
 242         req->in.h.opcode = opcode;
 243         req->in.h.nodeid = ff->nodeid;
 244         req->in.numargs = 1;
 245         req->in.args[0].size = sizeof(struct fuse_release_in);
 246         req->in.args[0].value = inarg;
 247 }
 248
 249 void fuse_release_common(struct file *file, bool isdir)
 250 {
 251         struct fuse_inode *fi = get_fuse_inode(file_inode(file));
 252         struct fuse_file *ff = file->private_data;
 253         struct fuse_req *req = ff->reserved_req;
 254         int opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
 255
 256         fuse_prepare_release(fi, ff, file->f_flags, opcode);
 257
 258         if (ff->flock) {
 259                 struct fuse_release_in *inarg = &req->misc.release.in;
 260                 inarg->release_flags |= FUSE_RELEASE_FLOCK_UNLOCK;
 261                 inarg->lock_owner = fuse_lock_owner_id(ff->fc,
 262                                                        (fl_owner_t) file);
 263         }
 264         /* Hold inode until release is finished */
 265         req->misc.release.inode = igrab(file_inode(file));
 266
 267         /*
 268          * Normally this will send the RELEASE request, however if
 269          * some asynchronous READ or WRITE requests are outstanding,
 270          * the sending will be delayed.
 271          *
 272          * Make the release synchronous if this is a fuseblk mount,
 273          * synchronous RELEASE is allowed (and desirable) in this case
 274          * because the server can be trusted not to screw up.
 275          */
 276         fuse_file_put(ff, ff->fc->destroy_req != NULL, isdir);
 277 }
 278
 279 static int fuse_open(struct inode *inode, struct file *file)
 280 {
 281         return fuse_open_common(inode, file, false);
 282 }
 283
 284 static int fuse_release(struct inode *inode, struct file *file)
 285 {
 286         struct fuse_conn *fc = get_fuse_conn(inode);
 287
 288         /* see fuse_vma_close() for !writeback_cache case */
 289         if (fc->writeback_cache)
 290                 write_inode_now(inode, 1);
 291
 292         fuse_release_common(file, false);
 293
 294         /* return value is ignored by VFS */
 295         return 0;
 296 }
 297
 298 void fuse_sync_release(struct fuse_inode *fi, struct fuse_file *ff, int flags)
 299 {
 300         WARN_ON(refcount_read(&ff->count) > 1);
 301         fuse_prepare_release(fi, ff, flags, FUSE_RELEASE);
 302         /*
 303          * iput(NULL) is a no-op and since the refcount is 1 and everything's
 304          * synchronous, we are fine with not doing igrab() here"
 305          */
 306         fuse_file_put(ff, true, false);
 307 }
 308 EXPORT_SYMBOL_GPL(fuse_sync_release);
 309
 310 /*
 311  * Scramble the ID space with XTEA, so that the value of the files_struct
 312  * pointer is not exposed to userspace.
 313  */
 314 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
 315 {
 316         u32 *k = fc->scramble_key;
 317         u64 v = (unsigned long) id;
 318         u32 v0 = v;
 319         u32 v1 = v >> 32;
 320         u32 sum = 0;
 321         int i;
 322
 323         for (i = 0; i < 32; i++) {
 324                 v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
 325                 sum += 0x9E3779B9;
 326                 v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
 327         }
 328
 329         return (u64) v0 + ((u64) v1 << 32);
 330 }
 331
 332 static struct fuse_req *fuse_find_writeback(struct fuse_inode *fi,
 333                                             pgoff_t idx_from, pgoff_t idx_to)
 334 {
 335         struct fuse_req *req;
 336
 337         list_for_each_entry(req, &fi->writepages, writepages_entry) {
 338                 pgoff_t curr_index;
 339
 340                 WARN_ON(get_fuse_inode(req->inode) != fi);
 341                 curr_index = req->misc.write.in.offset >> PAGE_SHIFT;
 342                 if (idx_from < curr_index + req->num_pages &&
 343                     curr_index <= idx_to) {
 344                         return req;
 345                 }
 346         }
 347         return NULL;
 348 }
 349
 350 /*
 351  * Check if any page in a range is under writeback
 352  *
 353  * This is currently done by walking the list of writepage requests
 354  * for the inode, which can be pretty inefficient.
 355  */
 356 static bool fuse_range_is_writeback(struct inode *inode, pgoff_t idx_from,
 357                                    pgoff_t idx_to)
 358 {
 359         struct fuse_inode *fi = get_fuse_inode(inode);
 360         bool found;
 361
 362         spin_lock(&fi->lock);
 363         found = fuse_find_writeback(fi, idx_from, idx_to);
 364         spin_unlock(&fi->lock);
 365
 366         return found;
 367 }
 368
 369 static inline bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
 370 {
 371         return fuse_range_is_writeback(inode, index, index);
 372 }
 373
 374 /*
 375  * Wait for page writeback to be completed.
 376  *
 377  * Since fuse doesn't rely on the VM writeback tracking, this has to
 378  * use some other means.
 379  */
 380 static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
 381 {
 382         struct fuse_inode *fi = get_fuse_inode(inode);
 383
 384         wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
 385         return 0;
 386 }
 387
 388 /*
 389  * Wait for all pending writepages on the inode to finish.
 390  *
 391  * This is currently done by blocking further writes with FUSE_NOWRITE
 392  * and waiting for all sent writes to complete.
 393  *
 394  * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
 395  * could conflict with truncation.
 396  */
 397 static void fuse_sync_writes(struct inode *inode)
 398 {
 399         fuse_set_nowrite(inode);
 400         fuse_release_nowrite(inode);
 401 }
 402
 403 static int fuse_flush(struct file *file, fl_owner_t id)
 404 {
 405         struct inode *inode = file_inode(file);
 406         struct fuse_conn *fc = get_fuse_conn(inode);
 407         struct fuse_file *ff = file->private_data;
 408         struct fuse_req *req;
 409         struct fuse_flush_in inarg;
 410         int err;
 411
 412         if (is_bad_inode(inode))
 413                 return -EIO;
 414
 415         if (fc->no_flush)
 416                 return 0;
 417
 418         err = write_inode_now(inode, 1);
 419         if (err)
 420                 return err;
 421
 422         inode_lock(inode);
 423         fuse_sync_writes(inode);
 424         inode_unlock(inode);
 425
 426         err = filemap_check_errors(file->f_mapping);
 427         if (err)
 428                 return err;
 429
 430         req = fuse_get_req_nofail_nopages(fc, file);
 431         memset(&inarg, 0, sizeof(inarg));
 432         inarg.fh = ff->fh;
 433         inarg.lock_owner = fuse_lock_owner_id(fc, id);
 434         req->in.h.opcode = FUSE_FLUSH;
 435         req->in.h.nodeid = get_node_id(inode);
 436         req->in.numargs = 1;
 437         req->in.args[0].size = sizeof(inarg);
 438         req->in.args[0].value = &inarg;
 439         __set_bit(FR_FORCE, &req->flags);
 440         fuse_request_send(fc, req);
 441         err = req->out.h.error;
 442         fuse_put_request(fc, req);
 443         if (err == -ENOSYS) {
 444                 fc->no_flush = 1;
 445                 err = 0;
 446         }
 447         return err;
 448 }
 449
 450 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
 451                       int datasync, int opcode)
 452 {
 453         struct inode *inode = file->f_mapping->host;
 454         struct fuse_conn *fc = get_fuse_conn(inode);
 455         struct fuse_file *ff = file->private_data;
 456         FUSE_ARGS(args);
 457         struct fuse_fsync_in inarg;
 458
 459         memset(&inarg, 0, sizeof(inarg));
 460         inarg.fh = ff->fh;
 461         inarg.fsync_flags = datasync ? 1 : 0;
 462         args.in.h.opcode = opcode;
 463         args.in.h.nodeid = get_node_id(inode);
 464         args.in.numargs = 1;
 465         args.in.args[0].size = sizeof(inarg);
 466         args.in.args[0].value = &inarg;
 467         return fuse_simple_request(fc, &args);
 468 }
 469
 470 static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 471                       int datasync)
 472 {
 473         struct inode *inode = file->f_mapping->host;
 474         struct fuse_conn *fc = get_fuse_conn(inode);
 475         int err;
 476
 477         if (is_bad_inode(inode))
 478                 return -EIO;
 479
 480         inode_lock(inode);
 481
 482         /*
 483          * Start writeback against all dirty pages of the inode, then
 484          * wait for all outstanding writes, before sending the FSYNC
 485          * request.
 486          */
 487         err = file_write_and_wait_range(file, start, end);
 488         if (err)
 489                 goto out;
 490
 491         fuse_sync_writes(inode);
 492
 493         /*
 494          * Due to implementation of fuse writeback
 495          * file_write_and_wait_range() does not catch errors.
 496          * We have to do this directly after fuse_sync_writes()
 497          */
 498         err = file_check_and_advance_wb_err(file);
 499         if (err)
 500                 goto out;
 501
 502         err = sync_inode_metadata(inode, 1);
 503         if (err)
 504                 goto out;
 505
 506         if (fc->no_fsync)
 507                 goto out;
 508
 509         err = fuse_fsync_common(file, start, end, datasync, FUSE_FSYNC);
 510         if (err == -ENOSYS) {
 511                 fc->no_fsync = 1;
 512                 err = 0;
 513         }
 514 out:
 515         inode_unlock(inode);
 516
 517         return err;
 518 }
 519
 520 void fuse_read_fill(struct fuse_req *req, struct file *file, loff_t pos,
 521                     size_t count, int opcode)
 522 {
 523         struct fuse_read_in *inarg = &req->misc.read.in;
 524         struct fuse_file *ff = file->private_data;
 525
 526         inarg->fh = ff->fh;
 527         inarg->offset = pos;
 528         inarg->size = count;
 529         inarg->flags = file->f_flags;
 530         req->in.h.opcode = opcode;
 531         req->in.h.nodeid = ff->nodeid;
 532         req->in.numargs = 1;
 533         req->in.args[0].size = sizeof(struct fuse_read_in);
 534         req->in.args[0].value = inarg;
 535         req->out.argvar = 1;
 536         req->out.numargs = 1;
 537         req->out.args[0].size = count;
 538 }
 539
 540 static void fuse_release_user_pages(struct fuse_req *req, bool should_dirty)
 541 {
 542         unsigned i;
 543
 544         for (i = 0; i < req->num_pages; i++) {
 545                 struct page *page = req->pages[i];
 546                 if (should_dirty)
 547                         set_page_dirty_lock(page);
 548                 put_page(page);
 549         }
 550 }
 551
 552 static void fuse_io_release(struct kref *kref)
 553 {
 554         kfree(container_of(kref, struct fuse_io_priv, refcnt));
 555 }
 556
 557 static ssize_t fuse_get_res_by_io(struct fuse_io_priv *io)
 558 {
 559         if (io->err)
 560                 return io->err;
 561
 562         if (io->bytes >= 0 && io->write)
 563                 return -EIO;
 564
 565         return io->bytes < 0 ? io->size : io->bytes;
 566 }
 567
 568 /**
 569  * In case of short read, the caller sets 'pos' to the position of
 570  * actual end of fuse request in IO request. Otherwise, if bytes_requested
 571  * == bytes_transferred or rw == WRITE, the caller sets 'pos' to -1.
 572  *
 573  * An example:
 574  * User requested DIO read of 64K. It was splitted into two 32K fuse requests,
 575  * both submitted asynchronously. The first of them was ACKed by userspace as
 576  * fully completed (req->out.args[0].size == 32K) resulting in pos == -1. The
 577  * second request was ACKed as short, e.g. only 1K was read, resulting in
 578  * pos == 33K.
 579  *
 580  * Thus, when all fuse requests are completed, the minimal non-negative 'pos'
 581  * will be equal to the length of the longest contiguous fragment of
 582  * transferred data starting from the beginning of IO request.
 583  */
 584 static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
 585 {
 586         int left;
 587
 588         spin_lock(&io->lock);
 589         if (err)
 590                 io->err = io->err ? : err;
 591         else if (pos >= 0 && (io->bytes < 0 || pos < io->bytes))
 592                 io->bytes = pos;
 593
 594         left = --io->reqs;
 595         if (!left && io->blocking)
 596                 complete(io->done);
 597         spin_unlock(&io->lock);
 598
 599         if (!left && !io->blocking) {
 600                 ssize_t res = fuse_get_res_by_io(io);
 601
 602                 if (res >= 0) {
 603                         struct inode *inode = file_inode(io->iocb->ki_filp);
 604                         struct fuse_conn *fc = get_fuse_conn(inode);
 605                         struct fuse_inode *fi = get_fuse_inode(inode);
 606
 607                         spin_lock(&fi->lock);
 608                         fi->attr_version = atomic64_inc_return(&fc->attr_version);
 609                         spin_unlock(&fi->lock);
 610                 }
 611
 612                 io->iocb->ki_complete(io->iocb, res, 0);
 613         }
 614
 615         kref_put(&io->refcnt, fuse_io_release);
 616 }
 617
 618 static void fuse_aio_complete_req(struct fuse_conn *fc, struct fuse_req *req)
 619 {
 620         struct fuse_io_priv *io = req->io;
 621         ssize_t pos = -1;
 622
 623         fuse_release_user_pages(req, io->should_dirty);
 624
 625         if (io->write) {
 626                 if (req->misc.write.in.size != req->misc.write.out.size)
 627                         pos = req->misc.write.in.offset - io->offset +
 628                                 req->misc.write.out.size;
 629         } else {
 630                 if (req->misc.read.in.size != req->out.args[0].size)
 631                         pos = req->misc.read.in.offset - io->offset +
 632                                 req->out.args[0].size;
 633         }
 634
 635         fuse_aio_complete(io, req->out.h.error, pos);
 636 }
 637
 638 static size_t fuse_async_req_send(struct fuse_conn *fc, struct fuse_req *req,
 639                 size_t num_bytes, struct fuse_io_priv *io)
 640 {
 641         spin_lock(&io->lock);
 642         kref_get(&io->refcnt);
 643         io->size += num_bytes;
 644         io->reqs++;
 645         spin_unlock(&io->lock);
 646
 647         req->io = io;
 648         req->end = fuse_aio_complete_req;
 649
 650         __fuse_get_request(req);
 651         fuse_request_send_background(fc, req);
 652
 653         return num_bytes;
 654 }
 655
 656 static size_t fuse_send_read(struct fuse_req *req, struct fuse_io_priv *io,
 657                              loff_t pos, size_t count, fl_owner_t owner)
 658 {
 659         struct file *file = io->iocb->ki_filp;
 660         struct fuse_file *ff = file->private_data;
 661         struct fuse_conn *fc = ff->fc;
 662
 663         fuse_read_fill(req, file, pos, count, FUSE_READ);
 664         if (owner != NULL) {
 665                 struct fuse_read_in *inarg = &req->misc.read.in;
 666
 667                 inarg->read_flags |= FUSE_READ_LOCKOWNER;
 668                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 669         }
 670
 671         if (io->async)
 672                 return fuse_async_req_send(fc, req, count, io);
 673
 674         fuse_request_send(fc, req);
 675         return req->out.args[0].size;
 676 }
 677
 678 static void fuse_read_update_size(struct inode *inode, loff_t size,
 679                                   u64 attr_ver)
 680 {
 681         struct fuse_conn *fc = get_fuse_conn(inode);
 682         struct fuse_inode *fi = get_fuse_inode(inode);
 683
 684         spin_lock(&fi->lock);
 685         if (attr_ver == fi->attr_version && size < inode->i_size &&
 686             !test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
 687                 fi->attr_version = atomic64_inc_return(&fc->attr_version);
 688                 i_size_write(inode, size);
 689         }
 690         spin_unlock(&fi->lock);
 691 }
 692
 693 static void fuse_short_read(struct fuse_req *req, struct inode *inode,
 694                             u64 attr_ver)
 695 {
 696         size_t num_read = req->out.args[0].size;
 697         struct fuse_conn *fc = get_fuse_conn(inode);
 698
 699         if (fc->writeback_cache) {
 700                 /*
 701                  * A hole in a file. Some data after the hole are in page cache,
 702                  * but have not reached the client fs yet. So, the hole is not
 703                  * present there.
 704                  */
 705                 int i;
 706                 int start_idx = num_read >> PAGE_SHIFT;
 707                 size_t off = num_read & (PAGE_SIZE - 1);
 708
 709                 for (i = start_idx; i < req->num_pages; i++) {
 710                         zero_user_segment(req->pages[i], off, PAGE_SIZE);
 711                         off = 0;
 712                 }
 713         } else {
 714                 loff_t pos = page_offset(req->pages[0]) + num_read;
 715                 fuse_read_update_size(inode, pos, attr_ver);
 716         }
 717 }
 718
 719 static int fuse_do_readpage(struct file *file, struct page *page)
 720 {
 721         struct kiocb iocb;
 722         struct fuse_io_priv io;
 723         struct inode *inode = page->mapping->host;
 724         struct fuse_conn *fc = get_fuse_conn(inode);
 725         struct fuse_req *req;
 726         size_t num_read;
 727         loff_t pos = page_offset(page);
 728         size_t count = PAGE_SIZE;
 729         u64 attr_ver;
 730         int err;
 731
 732         /*
 733          * Page writeback can extend beyond the lifetime of the
 734          * page-cache page, so make sure we read a properly synced
 735          * page.
 736          */
 737         fuse_wait_on_page_writeback(inode, page->index);
 738
 739         req = fuse_get_req(fc, 1);
 740         if (IS_ERR(req))
 741                 return PTR_ERR(req);
 742
 743         attr_ver = fuse_get_attr_version(fc);
 744
 745         req->out.page_zeroing = 1;
 746         req->out.argpages = 1;
 747         req->num_pages = 1;
 748         req->pages[0] = page;
 749         req->page_descs[0].length = count;
 750         init_sync_kiocb(&iocb, file);
 751         io = (struct fuse_io_priv) FUSE_IO_PRIV_SYNC(&iocb);
 752         num_read = fuse_send_read(req, &io, pos, count, NULL);
 753         err = req->out.h.error;
 754
 755         if (!err) {
 756                 /*
 757                  * Short read means EOF.  If file size is larger, truncate it
 758                  */
 759                 if (num_read < count)
 760                         fuse_short_read(req, inode, attr_ver);
 761
 762                 SetPageUptodate(page);
 763         }
 764
 765         fuse_put_request(fc, req);
 766
 767         return err;
 768 }
 769
 770 static int fuse_readpage(struct file *file, struct page *page)
 771 {
 772         struct inode *inode = page->mapping->host;
 773         int err;
 774
 775         err = -EIO;
 776         if (is_bad_inode(inode))
 777                 goto out;
 778
 779         err = fuse_do_readpage(file, page);
 780         fuse_invalidate_atime(inode);
 781  out:
 782         unlock_page(page);
 783         return err;
 784 }
 785
 786 static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
 787 {
 788         int i;
 789         size_t count = req->misc.read.in.size;
 790         size_t num_read = req->out.args[0].size;
 791         struct address_space *mapping = NULL;
 792
 793         for (i = 0; mapping == NULL && i < req->num_pages; i++)
 794                 mapping = req->pages[i]->mapping;
 795
 796         if (mapping) {
 797                 struct inode *inode = mapping->host;
 798
 799                 /*
 800                  * Short read means EOF. If file size is larger, truncate it
 801                  */
 802                 if (!req->out.h.error && num_read < count)
 803                         fuse_short_read(req, inode, req->misc.read.attr_ver);
 804
 805                 fuse_invalidate_atime(inode);
 806         }
 807
 808         for (i = 0; i < req->num_pages; i++) {
 809                 struct page *page = req->pages[i];
 810                 if (!req->out.h.error)
 811                         SetPageUptodate(page);
 812                 else
 813                         SetPageError(page);
 814                 unlock_page(page);
 815                 put_page(page);
 816         }
 817         if (req->ff)
 818                 fuse_file_put(req->ff, false, false);
 819 }
 820
 821 static void fuse_send_readpages(struct fuse_req *req, struct file *file)
 822 {
 823         struct fuse_file *ff = file->private_data;
 824         struct fuse_conn *fc = ff->fc;
 825         loff_t pos = page_offset(req->pages[0]);
 826         size_t count = req->num_pages << PAGE_SHIFT;
 827
 828         req->out.argpages = 1;
 829         req->out.page_zeroing = 1;
 830         req->out.page_replace = 1;
 831         fuse_read_fill(req, file, pos, count, FUSE_READ);
 832         req->misc.read.attr_ver = fuse_get_attr_version(fc);
 833         if (fc->async_read) {
 834                 req->ff = fuse_file_get(ff);
 835                 req->end = fuse_readpages_end;
 836                 fuse_request_send_background(fc, req);
 837         } else {
 838                 fuse_request_send(fc, req);
 839                 fuse_readpages_end(fc, req);
 840                 fuse_put_request(fc, req);
 841         }
 842 }
 843
 844 struct fuse_fill_data {
 845         struct fuse_req *req;
 846         struct file *file;
 847         struct inode *inode;
 848         unsigned nr_pages;
 849 };
 850
 851 static int fuse_readpages_fill(void *_data, struct page *page)
 852 {
 853         struct fuse_fill_data *data = _data;
 854         struct fuse_req *req = data->req;
 855         struct inode *inode = data->inode;
 856         struct fuse_conn *fc = get_fuse_conn(inode);
 857
 858         fuse_wait_on_page_writeback(inode, page->index);
 859
 860         if (req->num_pages &&
 861             (req->num_pages == fc->max_pages ||
 862              (req->num_pages + 1) * PAGE_SIZE > fc->max_read ||
 863              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 864                 unsigned int nr_alloc = min_t(unsigned int, data->nr_pages,
 865                                               fc->max_pages);
 866                 fuse_send_readpages(req, data->file);
 867                 if (fc->async_read)
 868                         req = fuse_get_req_for_background(fc, nr_alloc);
 869                 else
 870                         req = fuse_get_req(fc, nr_alloc);
 871
 872                 data->req = req;
 873                 if (IS_ERR(req)) {
 874                         unlock_page(page);
 875                         return PTR_ERR(req);
 876                 }
 877         }
 878
 879         if (WARN_ON(req->num_pages >= req->max_pages)) {
 880                 unlock_page(page);
 881                 fuse_put_request(fc, req);
 882                 return -EIO;
 883         }
 884
 885         get_page(page);
 886         req->pages[req->num_pages] = page;
 887         req->page_descs[req->num_pages].length = PAGE_SIZE;
 888         req->num_pages++;
 889         data->nr_pages--;
 890         return 0;
 891 }
 892
 893 static int fuse_readpages(struct file *file, struct address_space *mapping,
 894                           struct list_head *pages, unsigned nr_pages)
 895 {
 896         struct inode *inode = mapping->host;
 897         struct fuse_conn *fc = get_fuse_conn(inode);
 898         struct fuse_fill_data data;
 899         int err;
 900         unsigned int nr_alloc = min_t(unsigned int, nr_pages, fc->max_pages);
 901
 902         err = -EIO;
 903         if (is_bad_inode(inode))
 904                 goto out;
 905
 906         data.file = file;
 907         data.inode = inode;
 908         if (fc->async_read)
 909                 data.req = fuse_get_req_for_background(fc, nr_alloc);
 910         else
 911                 data.req = fuse_get_req(fc, nr_alloc);
 912         data.nr_pages = nr_pages;
 913         err = PTR_ERR(data.req);
 914         if (IS_ERR(data.req))
 915                 goto out;
 916
 917         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 918         if (!err) {
 919                 if (data.req->num_pages)
 920                         fuse_send_readpages(data.req, file);
 921                 else
 922                         fuse_put_request(fc, data.req);
 923         }
 924 out:
 925         return err;
 926 }
 927
 928 static ssize_t fuse_cache_read_iter(struct kiocb *iocb, struct iov_iter *to)
 929 {
 930         struct inode *inode = iocb->ki_filp->f_mapping->host;
 931         struct fuse_conn *fc = get_fuse_conn(inode);
 932
 933         /*
 934          * In auto invalidate mode, always update attributes on read.
 935          * Otherwise, only update if we attempt to read past EOF (to ensure
 936          * i_size is up to date).
 937          */
 938         if (fc->auto_inval_data ||
 939             (iocb->ki_pos + iov_iter_count(to) > i_size_read(inode))) {
 940                 int err;
 941                 err = fuse_update_attributes(inode, iocb->ki_filp);
 942                 if (err)
 943                         return err;
 944         }
 945
 946         return generic_file_read_iter(iocb, to);
 947 }
 948
 949 static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,
 950                             loff_t pos, size_t count)
 951 {
 952         struct fuse_write_in *inarg = &req->misc.write.in;
 953         struct fuse_write_out *outarg = &req->misc.write.out;
 954
 955         inarg->fh = ff->fh;
 956         inarg->offset = pos;
 957         inarg->size = count;
 958         req->in.h.opcode = FUSE_WRITE;
 959         req->in.h.nodeid = ff->nodeid;
 960         req->in.numargs = 2;
 961         if (ff->fc->minor < 9)
 962                 req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
 963         else
 964                 req->in.args[0].size = sizeof(struct fuse_write_in);
 965         req->in.args[0].value = inarg;
 966         req->in.args[1].size = count;
 967         req->out.numargs = 1;
 968         req->out.args[0].size = sizeof(struct fuse_write_out);
 969         req->out.args[0].value = outarg;
 970 }
 971
 972 static size_t fuse_send_write(struct fuse_req *req, struct fuse_io_priv *io,
 973                               loff_t pos, size_t count, fl_owner_t owner)
 974 {
 975         struct kiocb *iocb = io->iocb;
 976         struct file *file = iocb->ki_filp;
 977         struct fuse_file *ff = file->private_data;
 978         struct fuse_conn *fc = ff->fc;
 979         struct fuse_write_in *inarg = &req->misc.write.in;
 980
 981         fuse_write_fill(req, ff, pos, count);
 982         inarg->flags = file->f_flags;
 983         if (iocb->ki_flags & IOCB_DSYNC)
 984                 inarg->flags |= O_DSYNC;
 985         if (iocb->ki_flags & IOCB_SYNC)
 986                 inarg->flags |= O_SYNC;
 987         if (owner != NULL) {
 988                 inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
 989                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 990         }
 991
 992         if (io->async)
 993                 return fuse_async_req_send(fc, req, count, io);
 994
 995         fuse_request_send(fc, req);
 996         return req->misc.write.out.size;
 997 }
 998
 999 bool fuse_write_update_size(struct inode *inode, loff_t pos)
1000 {
1001         struct fuse_conn *fc = get_fuse_conn(inode);
1002         struct fuse_inode *fi = get_fuse_inode(inode);
1003         bool ret = false;
1004
1005         spin_lock(&fi->lock);
1006         fi->attr_version = atomic64_inc_return(&fc->attr_version);
1007         if (pos > inode->i_size) {
1008                 i_size_write(inode, pos);
1009                 ret = true;
1010         }
1011         spin_unlock(&fi->lock);
1012
1013         return ret;
1014 }
1015
1016 static size_t fuse_send_write_pages(struct fuse_req *req, struct kiocb *iocb,
1017                                     struct inode *inode, loff_t pos,
1018                                     size_t count)
1019 {
1020         size_t res;
1021         unsigned offset;
1022         unsigned i;
1023         struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
1024
1025         for (i = 0; i < req->num_pages; i++)
1026                 fuse_wait_on_page_writeback(inode, req->pages[i]->index);
1027
1028         res = fuse_send_write(req, &io, pos, count, NULL);
1029
1030         offset = req->page_descs[0].offset;
1031         count = res;
1032         for (i = 0; i < req->num_pages; i++) {
1033                 struct page *page = req->pages[i];
1034
1035                 if (!req->out.h.error && !offset && count >= PAGE_SIZE)
1036                         SetPageUptodate(page);
1037
1038                 if (count > PAGE_SIZE - offset)
1039                         count -= PAGE_SIZE - offset;
1040                 else
1041                         count = 0;
1042                 offset = 0;
1043
1044                 unlock_page(page);
1045                 put_page(page);
1046         }
1047
1048         return res;
1049 }
1050
1051 static ssize_t fuse_fill_write_pages(struct fuse_req *req,
1052                                struct address_space *mapping,
1053                                struct iov_iter *ii, loff_t pos)
1054 {
1055         struct fuse_conn *fc = get_fuse_conn(mapping->host);
1056         unsigned offset = pos & (PAGE_SIZE - 1);
1057         size_t count = 0;
1058         int err;
1059
1060         req->in.argpages = 1;
1061         req->page_descs[0].offset = offset;
1062
1063         do {
1064                 size_t tmp;
1065                 struct page *page;
1066                 pgoff_t index = pos >> PAGE_SHIFT;
1067                 size_t bytes = min_t(size_t, PAGE_SIZE - offset,
1068                                      iov_iter_count(ii));
1069
1070                 bytes = min_t(size_t, bytes, fc->max_write - count);
1071
1072  again:
1073                 err = -EFAULT;
1074                 if (iov_iter_fault_in_readable(ii, bytes))
1075                         break;
1076
1077                 err = -ENOMEM;
1078                 page = grab_cache_page_write_begin(mapping, index, 0);
1079                 if (!page)
1080                         break;
1081
1082                 if (mapping_writably_mapped(mapping))
1083                         flush_dcache_page(page);
1084
1085                 tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
1086                 flush_dcache_page(page);
1087
1088                 iov_iter_advance(ii, tmp);
1089                 if (!tmp) {
1090                         unlock_page(page);
1091                         put_page(page);
1092                         bytes = min(bytes, iov_iter_single_seg_count(ii));
1093                         goto again;
1094                 }
1095
1096                 err = 0;
1097                 req->pages[req->num_pages] = page;
1098                 req->page_descs[req->num_pages].length = tmp;
1099                 req->num_pages++;
1100
1101                 count += tmp;
1102                 pos += tmp;
1103                 offset += tmp;
1104                 if (offset == PAGE_SIZE)
1105                         offset = 0;
1106
1107                 if (!fc->big_writes)
1108                         break;
1109         } while (iov_iter_count(ii) && count < fc->max_write &&
1110                  req->num_pages < req->max_pages && offset == 0);
1111
1112         return count > 0 ? count : err;
1113 }
1114
1115 static inline unsigned int fuse_wr_pages(loff_t pos, size_t len,
1116                                      unsigned int max_pages)
1117 {
1118         return min_t(unsigned int,
1119                      ((pos + len - 1) >> PAGE_SHIFT) -
1120                      (pos >> PAGE_SHIFT) + 1,
1121                      max_pages);
1122 }
1123
1124 static ssize_t fuse_perform_write(struct kiocb *iocb,
1125                                   struct address_space *mapping,
1126                                   struct iov_iter *ii, loff_t pos)
1127 {
1128         struct inode *inode = mapping->host;
1129         struct fuse_conn *fc = get_fuse_conn(inode);
1130         struct fuse_inode *fi = get_fuse_inode(inode);
1131         int err = 0;
1132         ssize_t res = 0;
1133
1134         if (is_bad_inode(inode))
1135                 return -EIO;
1136
1137         if (inode->i_size < pos + iov_iter_count(ii))
1138                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1139
1140         do {
1141                 struct fuse_req *req;
1142                 ssize_t count;
1143                 unsigned int nr_pages = fuse_wr_pages(pos, iov_iter_count(ii),
1144                                                       fc->max_pages);
1145
1146                 req = fuse_get_req(fc, nr_pages);
1147                 if (IS_ERR(req)) {
1148                         err = PTR_ERR(req);
1149                         break;
1150                 }
1151
1152                 count = fuse_fill_write_pages(req, mapping, ii, pos);
1153                 if (count <= 0) {
1154                         err = count;
1155                 } else {
1156                         size_t num_written;
1157
1158                         num_written = fuse_send_write_pages(req, iocb, inode,
1159                                                             pos, count);
1160                         err = req->out.h.error;
1161                         if (!err) {
1162                                 res += num_written;
1163                                 pos += num_written;
1164
1165                                 /* break out of the loop on short write */
1166                                 if (num_written != count)
1167                                         err = -EIO;
1168                         }
1169                 }
1170                 fuse_put_request(fc, req);
1171         } while (!err && iov_iter_count(ii));
1172
1173         if (res > 0)
1174                 fuse_write_update_size(inode, pos);
1175
1176         clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1177         fuse_invalidate_attr(inode);
1178
1179         return res > 0 ? res : err;
1180 }
1181
1182 static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
1183 {
1184         struct file *file = iocb->ki_filp;
1185         struct address_space *mapping = file->f_mapping;
1186         ssize_t written = 0;
1187         ssize_t written_buffered = 0;
1188         struct inode *inode = mapping->host;
1189         ssize_t err;
1190         loff_t endbyte = 0;
1191
1192         if (get_fuse_conn(inode)->writeback_cache) {
1193                 /* Update size (EOF optimization) and mode (SUID clearing) */
1194                 err = fuse_update_attributes(mapping->host, file);
1195                 if (err)
1196                         return err;
1197
1198                 return generic_file_write_iter(iocb, from);
1199         }
1200
1201         inode_lock(inode);
1202
1203         /* We can write back this queue in page reclaim */
1204         current->backing_dev_info = inode_to_bdi(inode);
1205
1206         err = generic_write_checks(iocb, from);
1207         if (err <= 0)
1208                 goto out;
1209
1210         err = file_remove_privs(file);
1211         if (err)
1212                 goto out;
1213
1214         err = file_update_time(file);
1215         if (err)
1216                 goto out;
1217
1218         if (iocb->ki_flags & IOCB_DIRECT) {
1219                 loff_t pos = iocb->ki_pos;
1220                 written = generic_file_direct_write(iocb, from);
1221                 if (written < 0 || !iov_iter_count(from))
1222                         goto out;
1223
1224                 pos += written;
1225
1226                 written_buffered = fuse_perform_write(iocb, mapping, from, pos);
1227                 if (written_buffered < 0) {
1228                         err = written_buffered;
1229                         goto out;
1230                 }
1231                 endbyte = pos + written_buffered - 1;
1232
1233                 err = filemap_write_and_wait_range(file->f_mapping, pos,
1234                                                    endbyte);
1235                 if (err)
1236                         goto out;
1237
1238                 invalidate_mapping_pages(file->f_mapping,
1239                                          pos >> PAGE_SHIFT,
1240                                          endbyte >> PAGE_SHIFT);
1241
1242                 written += written_buffered;
1243                 iocb->ki_pos = pos + written_buffered;
1244         } else {
1245                 written = fuse_perform_write(iocb, mapping, from, iocb->ki_pos);
1246                 if (written >= 0)
1247                         iocb->ki_pos += written;
1248         }
1249 out:
1250         current->backing_dev_info = NULL;
1251         inode_unlock(inode);
1252         if (written > 0)
1253                 written = generic_write_sync(iocb, written);
1254
1255         return written ? written : err;
1256 }
1257
1258 static inline void fuse_page_descs_length_init(struct fuse_req *req,
1259                 unsigned index, unsigned nr_pages)
1260 {
1261         int i;
1262
1263         for (i = index; i < index + nr_pages; i++)
1264                 req->page_descs[i].length = PAGE_SIZE -
1265                         req->page_descs[i].offset;
1266 }
1267
1268 static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii)
1269 {
1270         return (unsigned long)ii->iov->iov_base + ii->iov_offset;
1271 }
1272
1273 static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
1274                                         size_t max_size)
1275 {
1276         return min(iov_iter_single_seg_count(ii), max_size);
1277 }
1278
1279 static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
1280                                size_t *nbytesp, int write)
1281 {
1282         size_t nbytes = 0;  /* # bytes already packed in req */
1283         ssize_t ret = 0;
1284
1285         /* Special case for kernel I/O: can copy directly into the buffer */
1286         if (iov_iter_is_kvec(ii)) {
1287                 unsigned long user_addr = fuse_get_user_addr(ii);
1288                 size_t frag_size = fuse_get_frag_size(ii, *nbytesp);
1289
1290                 if (write)
1291                         req->in.args[1].value = (void *) user_addr;
1292                 else
1293                         req->out.args[0].value = (void *) user_addr;
1294
1295                 iov_iter_advance(ii, frag_size);
1296                 *nbytesp = frag_size;
1297                 return 0;
1298         }
1299
1300         while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
1301                 unsigned npages;
1302                 size_t start;
1303                 ret = iov_iter_get_pages(ii, &req->pages[req->num_pages],
1304                                         *nbytesp - nbytes,
1305                                         req->max_pages - req->num_pages,
1306                                         &start);
1307                 if (ret < 0)
1308                         break;
1309
1310                 iov_iter_advance(ii, ret);
1311                 nbytes += ret;
1312
1313                 ret += start;
1314                 npages = (ret + PAGE_SIZE - 1) / PAGE_SIZE;
1315
1316                 req->page_descs[req->num_pages].offset = start;
1317                 fuse_page_descs_length_init(req, req->num_pages, npages);
1318
1319                 req->num_pages += npages;
1320                 req->page_descs[req->num_pages - 1].length -=
1321                         (PAGE_SIZE - ret) & (PAGE_SIZE - 1);
1322         }
1323
1324         if (write)
1325                 req->in.argpages = 1;
1326         else
1327                 req->out.argpages = 1;
1328
1329         *nbytesp = nbytes;
1330
1331         return ret < 0 ? ret : 0;
1332 }
1333
1334 ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
1335                        loff_t *ppos, int flags)
1336 {
1337         int write = flags & FUSE_DIO_WRITE;
1338         int cuse = flags & FUSE_DIO_CUSE;
1339         struct file *file = io->iocb->ki_filp;
1340         struct inode *inode = file->f_mapping->host;
1341         struct fuse_file *ff = file->private_data;
1342         struct fuse_conn *fc = ff->fc;
1343         size_t nmax = write ? fc->max_write : fc->max_read;
1344         loff_t pos = *ppos;
1345         size_t count = iov_iter_count(iter);
1346         pgoff_t idx_from = pos >> PAGE_SHIFT;
1347         pgoff_t idx_to = (pos + count - 1) >> PAGE_SHIFT;
1348         ssize_t res = 0;
1349         struct fuse_req *req;
1350         int err = 0;
1351
1352         if (io->async)
1353                 req = fuse_get_req_for_background(fc, iov_iter_npages(iter,
1354                                                                 fc->max_pages));
1355         else
1356                 req = fuse_get_req(fc, iov_iter_npages(iter, fc->max_pages));
1357         if (IS_ERR(req))
1358                 return PTR_ERR(req);
1359
1360         if (!cuse && fuse_range_is_writeback(inode, idx_from, idx_to)) {
1361                 if (!write)
1362                         inode_lock(inode);
1363                 fuse_sync_writes(inode);
1364                 if (!write)
1365                         inode_unlock(inode);
1366         }
1367
1368         io->should_dirty = !write && iter_is_iovec(iter);
1369         while (count) {
1370                 size_t nres;
1371                 fl_owner_t owner = current->files;
1372                 size_t nbytes = min(count, nmax);
1373                 err = fuse_get_user_pages(req, iter, &nbytes, write);
1374                 if (err && !nbytes)
1375                         break;
1376
1377                 if (write)
1378                         nres = fuse_send_write(req, io, pos, nbytes, owner);
1379                 else
1380                         nres = fuse_send_read(req, io, pos, nbytes, owner);
1381
1382                 if (!io->async)
1383                         fuse_release_user_pages(req, io->should_dirty);
1384                 if (req->out.h.error) {
1385                         err = req->out.h.error;
1386                         break;
1387                 } else if (nres > nbytes) {
1388                         res = 0;
1389                         err = -EIO;
1390                         break;
1391                 }
1392                 count -= nres;
1393                 res += nres;
1394                 pos += nres;
1395                 if (nres != nbytes)
1396                         break;
1397                 if (count) {
1398                         fuse_put_request(fc, req);
1399                         if (io->async)
1400                                 req = fuse_get_req_for_background(fc,
1401                                         iov_iter_npages(iter, fc->max_pages));
1402                         else
1403                                 req = fuse_get_req(fc, iov_iter_npages(iter,
1404                                                                 fc->max_pages));
1405                         if (IS_ERR(req))
1406                                 break;
1407                 }
1408         }
1409         if (!IS_ERR(req))
1410                 fuse_put_request(fc, req);
1411         if (res > 0)
1412                 *ppos = pos;
1413
1414         return res > 0 ? res : err;
1415 }
1416 EXPORT_SYMBOL_GPL(fuse_direct_io);
1417
1418 static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
1419                                   struct iov_iter *iter,
1420                                   loff_t *ppos)
1421 {
1422         ssize_t res;
1423         struct inode *inode = file_inode(io->iocb->ki_filp);
1424
1425         if (is_bad_inode(inode))
1426                 return -EIO;
1427
1428         res = fuse_direct_io(io, iter, ppos, 0);
1429
1430         fuse_invalidate_atime(inode);
1431
1432         return res;
1433 }
1434
1435 static ssize_t fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
1436
1437 static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to)
1438 {
1439         ssize_t res;
1440
1441         if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
1442                 struct file *file = iocb->ki_filp;
1443
1444                 if (is_bad_inode(file_inode(file)))
1445                         return -EIO;
1446
1447                 res = fuse_direct_IO(iocb, to);
1448         } else {
1449                 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
1450
1451                 res = __fuse_direct_read(&io, to, &iocb->ki_pos);
1452         }
1453
1454         return res;
1455 }
1456
1457 static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
1458 {
1459         struct inode *inode = file_inode(iocb->ki_filp);
1460         struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
1461         ssize_t res;
1462
1463         if (is_bad_inode(inode))
1464                 return -EIO;
1465
1466         /* Don't allow parallel writes to the same file */
1467         inode_lock(inode);
1468         res = generic_write_checks(iocb, from);
1469         if (res > 0) {
1470                 if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
1471                         res = fuse_direct_IO(iocb, from);
1472                 } else {
1473                         res = fuse_direct_io(&io, from, &iocb->ki_pos,
1474                                              FUSE_DIO_WRITE);
1475                 }
1476         }
1477         fuse_invalidate_attr(inode);
1478         if (res > 0)
1479                 fuse_write_update_size(inode, iocb->ki_pos);
1480         inode_unlock(inode);
1481
1482         return res;
1483 }
1484
1485 static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
1486 {
1487         struct fuse_file *ff = iocb->ki_filp->private_data;
1488
1489         if (!(ff->open_flags & FOPEN_DIRECT_IO))
1490                 return fuse_cache_read_iter(iocb, to);
1491         else
1492                 return fuse_direct_read_iter(iocb, to);
1493 }
1494
1495 static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
1496 {
1497         struct fuse_file *ff = iocb->ki_filp->private_data;
1498
1499         if (!(ff->open_flags & FOPEN_DIRECT_IO))
1500                 return fuse_cache_write_iter(iocb, from);
1501         else
1502                 return fuse_direct_write_iter(iocb, from);
1503 }
1504
1505 static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
1506 {
1507         int i;
1508
1509         for (i = 0; i < req->num_pages; i++)
1510                 __free_page(req->pages[i]);
1511
1512         if (req->ff)
1513                 fuse_file_put(req->ff, false, false);
1514 }
1515
1516 static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
1517 {
1518         struct inode *inode = req->inode;
1519         struct fuse_inode *fi = get_fuse_inode(inode);
1520         struct backing_dev_info *bdi = inode_to_bdi(inode);
1521         int i;
1522
1523         list_del(&req->writepages_entry);
1524         for (i = 0; i < req->num_pages; i++) {
1525                 dec_wb_stat(&bdi->wb, WB_WRITEBACK);
1526                 dec_node_page_state(req->pages[i], NR_WRITEBACK_TEMP);
1527                 wb_writeout_inc(&bdi->wb);
1528         }
1529         wake_up(&fi->page_waitq);
1530 }
1531
1532 /* Called under fi->lock, may release and reacquire it */
1533 static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req,
1534                                 loff_t size)
1535 __releases(fi->lock)
1536 __acquires(fi->lock)
1537 {
1538         struct fuse_req *aux, *next;
1539         struct fuse_inode *fi = get_fuse_inode(req->inode);
1540         struct fuse_write_in *inarg = &req->misc.write.in;
1541         __u64 data_size = req->num_pages * PAGE_SIZE;
1542         bool queued;
1543
1544         if (inarg->offset + data_size <= size) {
1545                 inarg->size = data_size;
1546         } else if (inarg->offset < size) {
1547                 inarg->size = size - inarg->offset;
1548         } else {
1549                 /* Got truncated off completely */
1550                 goto out_free;
1551         }
1552
1553         req->in.args[1].size = inarg->size;
1554         queued = fuse_request_queue_background(fc, req);
1555         /* Fails on broken connection only */
1556         if (unlikely(!queued))
1557                 goto out_free;
1558
1559         fi->writectr++;
1560         return;
1561
1562  out_free:
1563         fuse_writepage_finish(fc, req);
1564         spin_unlock(&fi->lock);
1565
1566         /* After fuse_writepage_finish() aux request list is private */
1567         for (aux = req->misc.write.next; aux; aux = next) {
1568                 next = aux->misc.write.next;
1569                 aux->misc.write.next = NULL;
1570                 fuse_writepage_free(fc, aux);
1571                 fuse_put_request(fc, aux);
1572         }
1573
1574         fuse_writepage_free(fc, req);
1575         fuse_put_request(fc, req);
1576         spin_lock(&fi->lock);
1577 }
1578
1579 /*
1580  * If fi->writectr is positive (no truncate or fsync going on) send
1581  * all queued writepage requests.
1582  *
1583  * Called with fi->lock
1584  */
1585 void fuse_flush_writepages(struct inode *inode)
1586 __releases(fi->lock)
1587 __acquires(fi->lock)
1588 {
1589         struct fuse_conn *fc = get_fuse_conn(inode);
1590         struct fuse_inode *fi = get_fuse_inode(inode);
1591         size_t crop = i_size_read(inode);
1592         struct fuse_req *req;
1593
1594         while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
1595                 req = list_entry(fi->queued_writes.next, struct fuse_req, list);
1596                 list_del_init(&req->list);
1597                 fuse_send_writepage(fc, req, crop);
1598         }
1599 }
1600
1601 static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
1602 {
1603         struct inode *inode = req->inode;
1604         struct fuse_inode *fi = get_fuse_inode(inode);
1605
1606         mapping_set_error(inode->i_mapping, req->out.h.error);
1607         spin_lock(&fi->lock);
1608         while (req->misc.write.next) {
1609                 struct fuse_conn *fc = get_fuse_conn(inode);
1610                 struct fuse_write_in *inarg = &req->misc.write.in;
1611                 struct fuse_req *next = req->misc.write.next;
1612                 req->misc.write.next = next->misc.write.next;
1613                 next->misc.write.next = NULL;
1614                 next->ff = fuse_file_get(req->ff);
1615                 list_add(&next->writepages_entry, &fi->writepages);
1616
1617                 /*
1618                  * Skip fuse_flush_writepages() to make it easy to crop requests
1619                  * based on primary request size.
1620                  *
1621                  * 1st case (trivial): there are no concurrent activities using
1622                  * fuse_set/release_nowrite.  Then we're on safe side because
1623                  * fuse_flush_writepages() would call fuse_send_writepage()
1624                  * anyway.
1625                  *
1626                  * 2nd case: someone called fuse_set_nowrite and it is waiting
1627                  * now for completion of all in-flight requests.  This happens
1628                  * rarely and no more than once per page, so this should be
1629                  * okay.
1630                  *
1631                  * 3rd case: someone (e.g. fuse_do_setattr()) is in the middle
1632                  * of fuse_set_nowrite..fuse_release_nowrite section.  The fact
1633                  * that fuse_set_nowrite returned implies that all in-flight
1634                  * requests were completed along with all of their secondary
1635                  * requests.  Further primary requests are blocked by negative
1636                  * writectr.  Hence there cannot be any in-flight requests and
1637                  * no invocations of fuse_writepage_end() while we're in
1638                  * fuse_set_nowrite..fuse_release_nowrite section.
1639                  */
1640                 fuse_send_writepage(fc, next, inarg->offset + inarg->size);
1641         }
1642         fi->writectr--;
1643         fuse_writepage_finish(fc, req);
1644         spin_unlock(&fi->lock);
1645         fuse_writepage_free(fc, req);
1646 }
1647
1648 static struct fuse_file *__fuse_write_file_get(struct fuse_conn *fc,
1649                                                struct fuse_inode *fi)
1650 {
1651         struct fuse_file *ff = NULL;
1652
1653         spin_lock(&fi->lock);
1654         if (!list_empty(&fi->write_files)) {
1655                 ff = list_entry(fi->write_files.next, struct fuse_file,
1656                                 write_entry);
1657                 fuse_file_get(ff);
1658         }
1659         spin_unlock(&fi->lock);
1660
1661         return ff;
1662 }
1663
1664 static struct fuse_file *fuse_write_file_get(struct fuse_conn *fc,
1665                                              struct fuse_inode *fi)
1666 {
1667         struct fuse_file *ff = __fuse_write_file_get(fc, fi);
1668         WARN_ON(!ff);
1669         return ff;
1670 }
1671
1672 int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
1673 {
1674         struct fuse_conn *fc = get_fuse_conn(inode);
1675         struct fuse_inode *fi = get_fuse_inode(inode);
1676         struct fuse_file *ff;
1677         int err;
1678
1679         ff = __fuse_write_file_get(fc, fi);
1680         err = fuse_flush_times(inode, ff);
1681         if (ff)
1682                 fuse_file_put(ff, false, false);
1683
1684         return err;
1685 }
1686
1687 static int fuse_writepage_locked(struct page *page)
1688 {
1689         struct address_space *mapping = page->mapping;
1690         struct inode *inode = mapping->host;
1691         struct fuse_conn *fc = get_fuse_conn(inode);
1692         struct fuse_inode *fi = get_fuse_inode(inode);
1693         struct fuse_req *req;
1694         struct page *tmp_page;
1695         int error = -ENOMEM;
1696
1697         set_page_writeback(page);
1698
1699         req = fuse_request_alloc_nofs(1);
1700         if (!req)
1701                 goto err;
1702
1703         /* writeback always goes to bg_queue */
1704         __set_bit(FR_BACKGROUND, &req->flags);
1705         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1706         if (!tmp_page)
1707                 goto err_free;
1708
1709         error = -EIO;
1710         req->ff = fuse_write_file_get(fc, fi);
1711         if (!req->ff)
1712                 goto err_nofile;
1713
1714         fuse_write_fill(req, req->ff, page_offset(page), 0);
1715
1716         copy_highpage(tmp_page, page);
1717         req->misc.write.in.write_flags |= FUSE_WRITE_CACHE;
1718         req->misc.write.next = NULL;
1719         req->in.argpages = 1;
1720         req->num_pages = 1;
1721         req->pages[0] = tmp_page;
1722         req->page_descs[0].offset = 0;
1723         req->page_descs[0].length = PAGE_SIZE;
1724         req->end = fuse_writepage_end;
1725         req->inode = inode;
1726
1727         inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
1728         inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);
1729
1730         spin_lock(&fi->lock);
1731         list_add(&req->writepages_entry, &fi->writepages);
1732         list_add_tail(&req->list, &fi->queued_writes);
1733         fuse_flush_writepages(inode);
1734         spin_unlock(&fi->lock);
1735
1736         end_page_writeback(page);
1737
1738         return 0;
1739
1740 err_nofile:
1741         __free_page(tmp_page);
1742 err_free:
1743         fuse_request_free(req);
1744 err:
1745         mapping_set_error(page->mapping, error);
1746         end_page_writeback(page);
1747         return error;
1748 }
1749
1750 static int fuse_writepage(struct page *page, struct writeback_control *wbc)
1751 {
1752         int err;
1753
1754         if (fuse_page_is_writeback(page->mapping->host, page->index)) {
1755                 /*
1756                  * ->writepages() should be called for sync() and friends.  We
1757                  * should only get here on direct reclaim and then we are
1758                  * allowed to skip a page which is already in flight
1759                  */
1760                 WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
1761
1762                 redirty_page_for_writepage(wbc, page);
1763                 return 0;
1764         }
1765
1766         err = fuse_writepage_locked(page);
1767         unlock_page(page);
1768
1769         return err;
1770 }
1771
1772 struct fuse_fill_wb_data {
1773         struct fuse_req *req;
1774         struct fuse_file *ff;
1775         struct inode *inode;
1776         struct page **orig_pages;
1777 };
1778
1779 static void fuse_writepages_send(struct fuse_fill_wb_data *data)
1780 {
1781         struct fuse_req *req = data->req;
1782         struct inode *inode = data->inode;
1783         struct fuse_inode *fi = get_fuse_inode(inode);
1784         int num_pages = req->num_pages;
1785         int i;
1786
1787         req->ff = fuse_file_get(data->ff);
1788         spin_lock(&fi->lock);
1789         list_add_tail(&req->list, &fi->queued_writes);
1790         fuse_flush_writepages(inode);
1791         spin_unlock(&fi->lock);
1792
1793         for (i = 0; i < num_pages; i++)
1794                 end_page_writeback(data->orig_pages[i]);
1795 }
1796
1797 /*
1798  * First recheck under fi->lock if the offending offset is still under
1799  * writeback.  If yes, then iterate auxiliary write requests, to see if there's
1800  * one already added for a page at this offset.  If there's none, then insert
1801  * this new request onto the auxiliary list, otherwise reuse the existing one by
1802  * copying the new page contents over to the old temporary page.
1803  */
1804 static bool fuse_writepage_in_flight(struct fuse_req *new_req,
1805                                      struct page *page)
1806 {
1807         struct fuse_conn *fc = get_fuse_conn(new_req->inode);
1808         struct fuse_inode *fi = get_fuse_inode(new_req->inode);
1809         struct fuse_req *tmp;
1810         struct fuse_req *old_req;
1811
1812         WARN_ON(new_req->num_pages != 0);
1813
1814         spin_lock(&fi->lock);
1815         list_del(&new_req->writepages_entry);
1816         old_req = fuse_find_writeback(fi, page->index, page->index);
1817         if (!old_req) {
1818                 list_add(&new_req->writepages_entry, &fi->writepages);
1819                 spin_unlock(&fi->lock);
1820                 return false;
1821         }
1822
1823         new_req->num_pages = 1;
1824         for (tmp = old_req->misc.write.next; tmp; tmp = tmp->misc.write.next) {
1825                 pgoff_t curr_index;
1826
1827                 WARN_ON(tmp->inode != new_req->inode);
1828                 curr_index = tmp->misc.write.in.offset >> PAGE_SHIFT;
1829                 if (curr_index == page->index) {
1830                         WARN_ON(tmp->num_pages != 1);
1831                         WARN_ON(!test_bit(FR_PENDING, &tmp->flags));
1832                         swap(tmp->pages[0], new_req->pages[0]);
1833                         break;
1834                 }
1835         }
1836
1837         if (!tmp) {
1838                 new_req->misc.write.next = old_req->misc.write.next;
1839                 old_req->misc.write.next = new_req;
1840         }
1841
1842         spin_unlock(&fi->lock);
1843
1844         if (tmp) {
1845                 struct backing_dev_info *bdi = inode_to_bdi(new_req->inode);
1846
1847                 dec_wb_stat(&bdi->wb, WB_WRITEBACK);
1848                 dec_node_page_state(new_req->pages[0], NR_WRITEBACK_TEMP);
1849                 wb_writeout_inc(&bdi->wb);
1850                 fuse_writepage_free(fc, new_req);
1851                 fuse_request_free(new_req);
1852         }
1853
1854         return true;
1855 }
1856
1857 static int fuse_writepages_fill(struct page *page,
1858                 struct writeback_control *wbc, void *_data)
1859 {
1860         struct fuse_fill_wb_data *data = _data;
1861         struct fuse_req *req = data->req;
1862         struct inode *inode = data->inode;
1863         struct fuse_inode *fi = get_fuse_inode(inode);
1864         struct fuse_conn *fc = get_fuse_conn(inode);
1865         struct page *tmp_page;
1866         bool is_writeback;
1867         int err;
1868
1869         if (!data->ff) {
1870                 err = -EIO;
1871                 data->ff = fuse_write_file_get(fc, get_fuse_inode(inode));
1872                 if (!data->ff)
1873                         goto out_unlock;
1874         }
1875
1876         /*
1877          * Being under writeback is unlikely but possible.  For example direct
1878          * read to an mmaped fuse file will set the page dirty twice; once when
1879          * the pages are faulted with get_user_pages(), and then after the read
1880          * completed.
1881          */
1882         is_writeback = fuse_page_is_writeback(inode, page->index);
1883
1884         if (req && req->num_pages &&
1885             (is_writeback || req->num_pages == fc->max_pages ||
1886              (req->num_pages + 1) * PAGE_SIZE > fc->max_write ||
1887              data->orig_pages[req->num_pages - 1]->index + 1 != page->index)) {
1888                 fuse_writepages_send(data);
1889                 data->req = NULL;
1890         } else if (req && req->num_pages == req->max_pages) {
1891                 if (!fuse_req_realloc_pages(fc, req, GFP_NOFS)) {
1892                         fuse_writepages_send(data);
1893                         req = data->req = NULL;
1894                 }
1895         }
1896
1897         err = -ENOMEM;
1898         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1899         if (!tmp_page)
1900                 goto out_unlock;
1901
1902         /*
1903          * The page must not be redirtied until the writeout is completed
1904          * (i.e. userspace has sent a reply to the write request).  Otherwise
1905          * there could be more than one temporary page instance for each real
1906          * page.
1907          *
1908          * This is ensured by holding the page lock in page_mkwrite() while
1909          * checking fuse_page_is_writeback().  We already hold the page lock
1910          * since clear_page_dirty_for_io() and keep it held until we add the
1911          * request to the fi->writepages list and increment req->num_pages.
1912          * After this fuse_page_is_writeback() will indicate that the page is
1913          * under writeback, so we can release the page lock.
1914          */
1915         if (data->req == NULL) {
1916                 struct fuse_inode *fi = get_fuse_inode(inode);
1917
1918                 err = -ENOMEM;
1919                 req = fuse_request_alloc_nofs(FUSE_REQ_INLINE_PAGES);
1920                 if (!req) {
1921                         __free_page(tmp_page);
1922                         goto out_unlock;
1923                 }
1924
1925                 fuse_write_fill(req, data->ff, page_offset(page), 0);
1926                 req->misc.write.in.write_flags |= FUSE_WRITE_CACHE;
1927                 req->misc.write.next = NULL;
1928                 req->in.argpages = 1;
1929                 __set_bit(FR_BACKGROUND, &req->flags);
1930                 req->num_pages = 0;
1931                 req->end = fuse_writepage_end;
1932                 req->inode = inode;
1933
1934                 spin_lock(&fi->lock);
1935                 list_add(&req->writepages_entry, &fi->writepages);
1936                 spin_unlock(&fi->lock);
1937
1938                 data->req = req;
1939         }
1940         set_page_writeback(page);
1941
1942         copy_highpage(tmp_page, page);
1943         req->pages[req->num_pages] = tmp_page;
1944         req->page_descs[req->num_pages].offset = 0;
1945         req->page_descs[req->num_pages].length = PAGE_SIZE;
1946
1947         inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
1948         inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);
1949
1950         err = 0;
1951         if (is_writeback && fuse_writepage_in_flight(req, page)) {
1952                 end_page_writeback(page);
1953                 data->req = NULL;
1954                 goto out_unlock;
1955         }
1956         data->orig_pages[req->num_pages] = page;
1957
1958         /*
1959          * Protected by fi->lock against concurrent access by
1960          * fuse_page_is_writeback().
1961          */
1962         spin_lock(&fi->lock);
1963         req->num_pages++;
1964         spin_unlock(&fi->lock);
1965
1966 out_unlock:
1967         unlock_page(page);
1968
1969         return err;
1970 }
1971
1972 static int fuse_writepages(struct address_space *mapping,
1973                            struct writeback_control *wbc)
1974 {
1975         struct inode *inode = mapping->host;
1976         struct fuse_conn *fc = get_fuse_conn(inode);
1977         struct fuse_fill_wb_data data;
1978         int err;
1979
1980         err = -EIO;
1981         if (is_bad_inode(inode))
1982                 goto out;
1983
1984         data.inode = inode;
1985         data.req = NULL;
1986         data.ff = NULL;
1987
1988         err = -ENOMEM;
1989         data.orig_pages = kcalloc(fc->max_pages,
1990                                   sizeof(struct page *),
1991                                   GFP_NOFS);
1992         if (!data.orig_pages)
1993                 goto out;
1994
1995         err = write_cache_pages(mapping, wbc, fuse_writepages_fill, &data);
1996         if (data.req) {
1997                 /* Ignore errors if we can write at least one page */
1998                 BUG_ON(!data.req->num_pages);
1999                 fuse_writepages_send(&data);
2000                 err = 0;
2001         }
2002         if (data.ff)
2003                 fuse_file_put(data.ff, false, false);
2004
2005         kfree(data.orig_pages);
2006 out:
2007         return err;
2008 }
2009
2010 /*
2011  * It's worthy to make sure that space is reserved on disk for the write,
2012  * but how to implement it without killing performance need more thinking.
2013  */
2014 static int fuse_write_begin(struct file *file, struct address_space *mapping,
2015                 loff_t pos, unsigned len, unsigned flags,
2016                 struct page **pagep, void **fsdata)
2017 {
2018         pgoff_t index = pos >> PAGE_SHIFT;
2019         struct fuse_conn *fc = get_fuse_conn(file_inode(file));
2020         struct page *page;
2021         loff_t fsize;
2022         int err = -ENOMEM;
2023
2024         WARN_ON(!fc->writeback_cache);
2025
2026         page = grab_cache_page_write_begin(mapping, index, flags);
2027         if (!page)
2028                 goto error;
2029
2030         fuse_wait_on_page_writeback(mapping->host, page->index);
2031
2032         if (PageUptodate(page) || len == PAGE_SIZE)
2033                 goto success;
2034         /*
2035          * Check if the start this page comes after the end of file, in which
2036          * case the readpage can be optimized away.
2037          */
2038         fsize = i_size_read(mapping->host);
2039         if (fsize <= (pos & PAGE_MASK)) {
2040                 size_t off = pos & ~PAGE_MASK;
2041                 if (off)
2042                         zero_user_segment(page, 0, off);
2043                 goto success;
2044         }
2045         err = fuse_do_readpage(file, page);
2046         if (err)
2047                 goto cleanup;
2048 success:
2049         *pagep = page;
2050         return 0;
2051
2052 cleanup:
2053         unlock_page(page);
2054         put_page(page);
2055 error:
2056         return err;
2057 }
2058
2059 static int fuse_write_end(struct file *file, struct address_space *mapping,
2060                 loff_t pos, unsigned len, unsigned copied,
2061                 struct page *page, void *fsdata)
2062 {
2063         struct inode *inode = page->mapping->host;
2064
2065         /* Haven't copied anything?  Skip zeroing, size extending, dirtying. */
2066         if (!copied)
2067                 goto unlock;
2068
2069         if (!PageUptodate(page)) {
2070                 /* Zero any unwritten bytes at the end of the page */
2071                 size_t endoff = (pos + copied) & ~PAGE_MASK;
2072                 if (endoff)
2073                         zero_user_segment(page, endoff, PAGE_SIZE);
2074                 SetPageUptodate(page);
2075         }
2076
2077         fuse_write_update_size(inode, pos + copied);
2078         set_page_dirty(page);
2079
2080 unlock:
2081         unlock_page(page);
2082         put_page(page);
2083
2084         return copied;
2085 }
2086
2087 static int fuse_launder_page(struct page *page)
2088 {
2089         int err = 0;
2090         if (clear_page_dirty_for_io(page)) {
2091                 struct inode *inode = page->mapping->host;
2092                 err = fuse_writepage_locked(page);
2093                 if (!err)
2094                         fuse_wait_on_page_writeback(inode, page->index);
2095         }
2096         return err;
2097 }
2098
2099 /*
2100  * Write back dirty pages now, because there may not be any suitable
2101  * open files later
2102  */
2103 static void fuse_vma_close(struct vm_area_struct *vma)
2104 {
2105         filemap_write_and_wait(vma->vm_file->f_mapping);
2106 }
2107
2108 /*
2109  * Wait for writeback against this page to complete before allowing it
2110  * to be marked dirty again, and hence written back again, possibly
2111  * before the previous writepage completed.
2112  *
2113  * Block here, instead of in ->writepage(), so that the userspace fs
2114  * can only block processes actually operating on the filesystem.
2115  *
2116  * Otherwise unprivileged userspace fs would be able to block
2117  * unrelated:
2118  *
2119  * - page migration
2120  * - sync(2)
2121  * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
2122  */
2123 static vm_fault_t fuse_page_mkwrite(struct vm_fault *vmf)
2124 {
2125         struct page *page = vmf->page;
2126         struct inode *inode = file_inode(vmf->vma->vm_file);
2127
2128         file_update_time(vmf->vma->vm_file);
2129         lock_page(page);
2130         if (page->mapping != inode->i_mapping) {
2131                 unlock_page(page);
2132                 return VM_FAULT_NOPAGE;
2133         }
2134
2135         fuse_wait_on_page_writeback(inode, page->index);
2136         return VM_FAULT_LOCKED;
2137 }
2138
2139 static const struct vm_operations_struct fuse_file_vm_ops = {
2140         .close          = fuse_vma_close,
2141         .fault          = filemap_fault,
2142         .map_pages      = filemap_map_pages,
2143         .page_mkwrite   = fuse_page_mkwrite,
2144 };
2145
2146 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
2147 {
2148         struct fuse_file *ff = file->private_data;
2149
2150         if (ff->open_flags & FOPEN_DIRECT_IO) {
2151                 /* Can't provide the coherency needed for MAP_SHARED */
2152                 if (vma->vm_flags & VM_MAYSHARE)
2153                         return -ENODEV;
2154
2155                 invalidate_inode_pages2(file->f_mapping);
2156
2157                 return generic_file_mmap(file, vma);
2158         }
2159
2160         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2161                 fuse_link_write_file(file);
2162
2163         file_accessed(file);
2164         vma->vm_ops = &fuse_file_vm_ops;
2165         return 0;
2166 }
2167
2168 static int convert_fuse_file_lock(struct fuse_conn *fc,
2169                                   const struct fuse_file_lock *ffl,
2170                                   struct file_lock *fl)
2171 {
2172         switch (ffl->type) {
2173         case F_UNLCK:
2174                 break;
2175
2176         case F_RDLCK:
2177         case F_WRLCK:
2178                 if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
2179                     ffl->end < ffl->start)
2180                         return -EIO;
2181
2182                 fl->fl_start = ffl->start;
2183                 fl->fl_end = ffl->end;
2184
2185                 /*
2186                  * Convert pid into init's pid namespace.  The locks API will
2187                  * translate it into the caller's pid namespace.
2188                  */
2189                 rcu_read_lock();
2190                 fl->fl_pid = pid_nr_ns(find_pid_ns(ffl->pid, fc->pid_ns), &init_pid_ns);
2191                 rcu_read_unlock();
2192                 break;
2193
2194         default:
2195                 return -EIO;
2196         }
2197         fl->fl_type = ffl->type;
2198         return 0;
2199 }
2200
2201 static void fuse_lk_fill(struct fuse_args *args, struct file *file,
2202                          const struct file_lock *fl, int opcode, pid_t pid,
2203                          int flock, struct fuse_lk_in *inarg)
2204 {
2205         struct inode *inode = file_inode(file);
2206         struct fuse_conn *fc = get_fuse_conn(inode);
2207         struct fuse_file *ff = file->private_data;
2208
2209         memset(inarg, 0, sizeof(*inarg));
2210         inarg->fh = ff->fh;
2211         inarg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
2212         inarg->lk.start = fl->fl_start;
2213         inarg->lk.end = fl->fl_end;
2214         inarg->lk.type = fl->fl_type;
2215         inarg->lk.pid = pid;
2216         if (flock)
2217                 inarg->lk_flags |= FUSE_LK_FLOCK;
2218         args->in.h.opcode = opcode;
2219         args->in.h.nodeid = get_node_id(inode);
2220         args->in.numargs = 1;
2221         args->in.args[0].size = sizeof(*inarg);
2222         args->in.args[0].value = inarg;
2223 }
2224
2225 static int fuse_getlk(struct file *file, struct file_lock *fl)
2226 {
2227         struct inode *inode = file_inode(file);
2228         struct fuse_conn *fc = get_fuse_conn(inode);
2229         FUSE_ARGS(args);
2230         struct fuse_lk_in inarg;
2231         struct fuse_lk_out outarg;
2232         int err;
2233
2234         fuse_lk_fill(&args, file, fl, FUSE_GETLK, 0, 0, &inarg);
2235         args.out.numargs = 1;
2236         args.out.args[0].size = sizeof(outarg);
2237         args.out.args[0].value = &outarg;
2238         err = fuse_simple_request(fc, &args);
2239         if (!err)
2240                 err = convert_fuse_file_lock(fc, &outarg.lk, fl);
2241
2242         return err;
2243 }
2244
2245 static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
2246 {
2247         struct inode *inode = file_inode(file);
2248         struct fuse_conn *fc = get_fuse_conn(inode);
2249         FUSE_ARGS(args);
2250         struct fuse_lk_in inarg;
2251         int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
2252         struct pid *pid = fl->fl_type != F_UNLCK ? task_tgid(current) : NULL;
2253         pid_t pid_nr = pid_nr_ns(pid, fc->pid_ns);
2254         int err;
2255
2256         if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
2257                 /* NLM needs asynchronous locks, which we don't support yet */
2258                 return -ENOLCK;
2259         }
2260
2261         /* Unlock on close is handled by the flush method */
2262         if ((fl->fl_flags & FL_CLOSE_POSIX) == FL_CLOSE_POSIX)
2263                 return 0;
2264
2265         fuse_lk_fill(&args, file, fl, opcode, pid_nr, flock, &inarg);
2266         err = fuse_simple_request(fc, &args);
2267
2268         /* locking is restartable */
2269         if (err == -EINTR)
2270                 err = -ERESTARTSYS;
2271
2272         return err;
2273 }
2274
2275 static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
2276 {
2277         struct inode *inode = file_inode(file);
2278         struct fuse_conn *fc = get_fuse_conn(inode);
2279         int err;
2280
2281         if (cmd == F_CANCELLK) {
2282                 err = 0;
2283         } else if (cmd == F_GETLK) {
2284                 if (fc->no_lock) {
2285                         posix_test_lock(file, fl);
2286                         err = 0;
2287                 } else
2288                         err = fuse_getlk(file, fl);
2289         } else {
2290                 if (fc->no_lock)
2291                         err = posix_lock_file(file, fl, NULL);
2292                 else
2293                         err = fuse_setlk(file, fl, 0);
2294         }
2295         return err;
2296 }
2297
2298 static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
2299 {
2300         struct inode *inode = file_inode(file);
2301         struct fuse_conn *fc = get_fuse_conn(inode);
2302         int err;
2303
2304         if (fc->no_flock) {
2305                 err = locks_lock_file_wait(file, fl);
2306         } else {
2307                 struct fuse_file *ff = file->private_data;
2308
2309                 /* emulate flock with POSIX locks */
2310                 ff->flock = true;
2311                 err = fuse_setlk(file, fl, 1);
2312         }
2313
2314         return err;
2315 }
2316
2317 static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
2318 {
2319         struct inode *inode = mapping->host;
2320         struct fuse_conn *fc = get_fuse_conn(inode);
2321         FUSE_ARGS(args);
2322         struct fuse_bmap_in inarg;
2323         struct fuse_bmap_out outarg;
2324         int err;
2325
2326         if (!inode->i_sb->s_bdev || fc->no_bmap)
2327                 return 0;
2328
2329         memset(&inarg, 0, sizeof(inarg));
2330         inarg.block = block;
2331         inarg.blocksize = inode->i_sb->s_blocksize;
2332         args.in.h.opcode = FUSE_BMAP;
2333         args.in.h.nodeid = get_node_id(inode);
2334         args.in.numargs = 1;
2335         args.in.args[0].size = sizeof(inarg);
2336         args.in.args[0].value = &inarg;
2337         args.out.numargs = 1;
2338         args.out.args[0].size = sizeof(outarg);
2339         args.out.args[0].value = &outarg;
2340         err = fuse_simple_request(fc, &args);
2341         if (err == -ENOSYS)
2342                 fc->no_bmap = 1;
2343
2344         return err ? 0 : outarg.block;
2345 }
2346
2347 static loff_t fuse_lseek(struct file *file, loff_t offset, int whence)
2348 {
2349         struct inode *inode = file->f_mapping->host;
2350         struct fuse_conn *fc = get_fuse_conn(inode);
2351         struct fuse_file *ff = file->private_data;
2352         FUSE_ARGS(args);
2353         struct fuse_lseek_in inarg = {
2354                 .fh = ff->fh,
2355                 .offset = offset,
2356                 .whence = whence
2357         };
2358         struct fuse_lseek_out outarg;
2359         int err;
2360
2361         if (fc->no_lseek)
2362                 goto fallback;
2363
2364         args.in.h.opcode = FUSE_LSEEK;
2365         args.in.h.nodeid = ff->nodeid;
2366         args.in.numargs = 1;
2367         args.in.args[0].size = sizeof(inarg);
2368         args.in.args[0].value = &inarg;
2369         args.out.numargs = 1;
2370         args.out.args[0].size = sizeof(outarg);
2371         args.out.args[0].value = &outarg;
2372         err = fuse_simple_request(fc, &args);
2373         if (err) {
2374                 if (err == -ENOSYS) {
2375                         fc->no_lseek = 1;
2376                         goto fallback;
2377                 }
2378                 return err;
2379         }
2380
2381         return vfs_setpos(file, outarg.offset, inode->i_sb->s_maxbytes);
2382
2383 fallback:
2384         err = fuse_update_attributes(inode, file);
2385         if (!err)
2386                 return generic_file_llseek(file, offset, whence);
2387         else
2388                 return err;
2389 }
2390
2391 static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
2392 {
2393         loff_t retval;
2394         struct inode *inode = file_inode(file);
2395
2396         switch (whence) {
2397         case SEEK_SET:
2398         case SEEK_CUR:
2399                  /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
2400                 retval = generic_file_llseek(file, offset, whence);
2401                 break;
2402         case SEEK_END:
2403                 inode_lock(inode);
2404                 retval = fuse_update_attributes(inode, file);
2405                 if (!retval)
2406                         retval = generic_file_llseek(file, offset, whence);
2407                 inode_unlock(inode);
2408                 break;
2409         case SEEK_HOLE:
2410         case SEEK_DATA:
2411                 inode_lock(inode);
2412                 retval = fuse_lseek(file, offset, whence);
2413                 inode_unlock(inode);
2414                 break;
2415         default:
2416                 retval = -EINVAL;
2417         }
2418
2419         return retval;
2420 }
2421
2422 /*
2423  * CUSE servers compiled on 32bit broke on 64bit kernels because the
2424  * ABI was defined to be 'struct iovec' which is different on 32bit
2425  * and 64bit.  Fortunately we can determine which structure the server
2426  * used from the size of the reply.
2427  */
2428 static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
2429                                      size_t transferred, unsigned count,
2430                                      bool is_compat)
2431 {
2432 #ifdef CONFIG_COMPAT
2433         if (count * sizeof(struct compat_iovec) == transferred) {
2434                 struct compat_iovec *ciov = src;
2435                 unsigned i;
2436
2437                 /*
2438                  * With this interface a 32bit server cannot support
2439                  * non-compat (i.e. ones coming from 64bit apps) ioctl
2440                  * requests
2441                  */
2442                 if (!is_compat)
2443                         return -EINVAL;
2444
2445                 for (i = 0; i < count; i++) {
2446                         dst[i].iov_base = compat_ptr(ciov[i].iov_base);
2447                         dst[i].iov_len = ciov[i].iov_len;
2448                 }
2449                 return 0;
2450         }
2451 #endif
2452
2453         if (count * sizeof(struct iovec) != transferred)
2454                 return -EIO;
2455
2456         memcpy(dst, src, transferred);
2457         return 0;
2458 }
2459
2460 /* Make sure iov_length() won't overflow */
2461 static int fuse_verify_ioctl_iov(struct fuse_conn *fc, struct iovec *iov,
2462                                  size_t count)
2463 {
2464         size_t n;
2465         u32 max = fc->max_pages << PAGE_SHIFT;
2466
2467         for (n = 0; n < count; n++, iov++) {
2468                 if (iov->iov_len > (size_t) max)
2469                         return -ENOMEM;
2470                 max -= iov->iov_len;
2471         }
2472         return 0;
2473 }
2474
2475 static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
2476                                  void *src, size_t transferred, unsigned count,
2477                                  bool is_compat)
2478 {
2479         unsigned i;
2480         struct fuse_ioctl_iovec *fiov = src;
2481
2482         if (fc->minor < 16) {
2483                 return fuse_copy_ioctl_iovec_old(dst, src, transferred,
2484                                                  count, is_compat);
2485         }
2486
2487         if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
2488                 return -EIO;
2489
2490         for (i = 0; i < count; i++) {
2491                 /* Did the server supply an inappropriate value? */
2492                 if (fiov[i].base != (unsigned long) fiov[i].base ||
2493                     fiov[i].len != (unsigned long) fiov[i].len)
2494                         return -EIO;
2495
2496                 dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
2497                 dst[i].iov_len = (size_t) fiov[i].len;
2498
2499 #ifdef CONFIG_COMPAT
2500                 if (is_compat &&
2501                     (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
2502                      (compat_size_t) dst[i].iov_len != fiov[i].len))
2503                         return -EIO;
2504 #endif
2505         }
2506
2507         return 0;
2508 }
2509
2510
2511 /*
2512  * For ioctls, there is no generic way to determine how much memory
2513  * needs to be read and/or written.  Furthermore, ioctls are allowed
2514  * to dereference the passed pointer, so the parameter requires deep
2515  * copying but FUSE has no idea whatsoever about what to copy in or
2516  * out.
2517  *
2518  * This is solved by allowing FUSE server to retry ioctl with
2519  * necessary in/out iovecs.  Let's assume the ioctl implementation
2520  * needs to read in the following structure.
2521  *
2522  * struct a {
2523  *      char    *buf;
2524  *      size_t  buflen;
2525  * }
2526  *
2527  * On the first callout to FUSE server, inarg->in_size and
2528  * inarg->out_size will be NULL; then, the server completes the ioctl
2529  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
2530  * the actual iov array to
2531  *
2532  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
2533  *
2534  * which tells FUSE to copy in the requested area and retry the ioctl.
2535  * On the second round, the server has access to the structure and
2536  * from that it can tell what to look for next, so on the invocation,
2537  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
2538  *
2539  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
2540  *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
2541  *
2542  * FUSE will copy both struct a and the pointed buffer from the
2543  * process doing the ioctl and retry ioctl with both struct a and the
2544  * buffer.
2545  *
2546  * This time, FUSE server has everything it needs and completes ioctl
2547  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
2548  *
2549  * Copying data out works the same way.
2550  *
2551  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
2552  * automatically initializes in and out iovs by decoding @cmd with
2553  * _IOC_* macros and the server is not allowed to request RETRY.  This
2554  * limits ioctl data transfers to well-formed ioctls and is the forced
2555  * behavior for all FUSE servers.
2556  */
2557 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
2558                    unsigned int flags)
2559 {
2560         struct fuse_file *ff = file->private_data;
2561         struct fuse_conn *fc = ff->fc;
2562         struct fuse_ioctl_in inarg = {
2563                 .fh = ff->fh,
2564                 .cmd = cmd,
2565                 .arg = arg,
2566                 .flags = flags
2567         };
2568         struct fuse_ioctl_out outarg;
2569         struct fuse_req *req = NULL;
2570         struct page **pages = NULL;
2571         struct iovec *iov_page = NULL;
2572         struct iovec *in_iov = NULL, *out_iov = NULL;
2573         unsigned int in_iovs = 0, out_iovs = 0, num_pages = 0, max_pages;
2574         size_t in_size, out_size, transferred, c;
2575         int err, i;
2576         struct iov_iter ii;
2577
2578 #if BITS_PER_LONG == 32
2579         inarg.flags |= FUSE_IOCTL_32BIT;
2580 #else
2581         if (flags & FUSE_IOCTL_COMPAT)
2582                 inarg.flags |= FUSE_IOCTL_32BIT;
2583 #endif
2584
2585         /* assume all the iovs returned by client always fits in a page */
2586         BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
2587
2588         err = -ENOMEM;
2589         pages = kcalloc(fc->max_pages, sizeof(pages[0]), GFP_KERNEL);
2590         iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
2591         if (!pages || !iov_page)
2592                 goto out;
2593
2594         /*
2595          * If restricted, initialize IO parameters as encoded in @cmd.
2596          * RETRY from server is not allowed.
2597          */
2598         if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
2599                 struct iovec *iov = iov_page;
2600
2601                 iov->iov_base = (void __user *)arg;
2602                 iov->iov_len = _IOC_SIZE(cmd);
2603
2604                 if (_IOC_DIR(cmd) & _IOC_WRITE) {
2605                         in_iov = iov;
2606                         in_iovs = 1;
2607                 }
2608
2609                 if (_IOC_DIR(cmd) & _IOC_READ) {
2610                         out_iov = iov;
2611                         out_iovs = 1;
2612                 }
2613         }
2614
2615  retry:
2616         inarg.in_size = in_size = iov_length(in_iov, in_iovs);
2617         inarg.out_size = out_size = iov_length(out_iov, out_iovs);
2618
2619         /*
2620          * Out data can be used either for actual out data or iovs,
2621          * make sure there always is at least one page.
2622          */
2623         out_size = max_t(size_t, out_size, PAGE_SIZE);
2624         max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
2625
2626         /* make sure there are enough buffer pages and init request with them */
2627         err = -ENOMEM;
2628         if (max_pages > fc->max_pages)
2629                 goto out;
2630         while (num_pages < max_pages) {
2631                 pages[num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
2632                 if (!pages[num_pages])
2633                         goto out;
2634                 num_pages++;
2635         }
2636
2637         req = fuse_get_req(fc, num_pages);
2638         if (IS_ERR(req)) {
2639                 err = PTR_ERR(req);
2640                 req = NULL;
2641                 goto out;
2642         }
2643         memcpy(req->pages, pages, sizeof(req->pages[0]) * num_pages);
2644         req->num_pages = num_pages;
2645         fuse_page_descs_length_init(req, 0, req->num_pages);
2646
2647         /* okay, let's send it to the client */
2648         req->in.h.opcode = FUSE_IOCTL;
2649         req->in.h.nodeid = ff->nodeid;
2650         req->in.numargs = 1;
2651         req->in.args[0].size = sizeof(inarg);
2652         req->in.args[0].value = &inarg;
2653         if (in_size) {
2654                 req->in.numargs++;
2655                 req->in.args[1].size = in_size;
2656                 req->in.argpages = 1;
2657
2658                 err = -EFAULT;
2659                 iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
2660                 for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= num_pages); i++) {
2661                         c = copy_page_from_iter(pages[i], 0, PAGE_SIZE, &ii);
2662                         if (c != PAGE_SIZE && iov_iter_count(&ii))
2663                                 goto out;
2664                 }
2665         }
2666
2667         req->out.numargs = 2;
2668         req->out.args[0].size = sizeof(outarg);
2669         req->out.args[0].value = &outarg;
2670         req->out.args[1].size = out_size;
2671         req->out.argpages = 1;
2672         req->out.argvar = 1;
2673
2674         fuse_request_send(fc, req);
2675         err = req->out.h.error;
2676         transferred = req->out.args[1].size;
2677         fuse_put_request(fc, req);
2678         req = NULL;
2679         if (err)
2680                 goto out;
2681
2682         /* did it ask for retry? */
2683         if (outarg.flags & FUSE_IOCTL_RETRY) {
2684                 void *vaddr;
2685
2686                 /* no retry if in restricted mode */
2687                 err = -EIO;
2688                 if (!(flags & FUSE_IOCTL_UNRESTRICTED))
2689                         goto out;
2690
2691                 in_iovs = outarg.in_iovs;
2692                 out_iovs = outarg.out_iovs;
2693
2694                 /*
2695                  * Make sure things are in boundary, separate checks
2696                  * are to protect against overflow.
2697                  */
2698                 err = -ENOMEM;
2699                 if (in_iovs > FUSE_IOCTL_MAX_IOV ||
2700                     out_iovs > FUSE_IOCTL_MAX_IOV ||
2701                     in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
2702                         goto out;
2703
2704                 vaddr = kmap_atomic(pages[0]);
2705                 err = fuse_copy_ioctl_iovec(fc, iov_page, vaddr,
2706                                             transferred, in_iovs + out_iovs,
2707                                             (flags & FUSE_IOCTL_COMPAT) != 0);
2708                 kunmap_atomic(vaddr);
2709                 if (err)
2710                         goto out;
2711
2712                 in_iov = iov_page;
2713                 out_iov = in_iov + in_iovs;
2714
2715                 err = fuse_verify_ioctl_iov(fc, in_iov, in_iovs);
2716                 if (err)
2717                         goto out;
2718
2719                 err = fuse_verify_ioctl_iov(fc, out_iov, out_iovs);
2720                 if (err)
2721                         goto out;
2722
2723                 goto retry;
2724         }
2725
2726         err = -EIO;
2727         if (transferred > inarg.out_size)
2728                 goto out;
2729
2730         err = -EFAULT;
2731         iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
2732         for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= num_pages); i++) {
2733                 c = copy_page_to_iter(pages[i], 0, PAGE_SIZE, &ii);
2734                 if (c != PAGE_SIZE && iov_iter_count(&ii))
2735                         goto out;
2736         }
2737         err = 0;
2738  out:
2739         if (req)
2740                 fuse_put_request(fc, req);
2741         free_page((unsigned long) iov_page);
2742         while (num_pages)
2743                 __free_page(pages[--num_pages]);
2744         kfree(pages);
2745
2746         return err ? err : outarg.result;
2747 }
2748 EXPORT_SYMBOL_GPL(fuse_do_ioctl);
2749
2750 long fuse_ioctl_common(struct file *file, unsigned int cmd,
2751                        unsigned long arg, unsigned int flags)
2752 {
2753         struct inode *inode = file_inode(file);
2754         struct fuse_conn *fc = get_fuse_conn(inode);
2755
2756         if (!fuse_allow_current_process(fc))
2757                 return -EACCES;
2758
2759         if (is_bad_inode(inode))
2760                 return -EIO;
2761
2762         return fuse_do_ioctl(file, cmd, arg, flags);
2763 }
2764
2765 static long fuse_file_ioctl(struct file *file, unsigned int cmd,
2766                             unsigned long arg)
2767 {
2768         return fuse_ioctl_common(file, cmd, arg, 0);
2769 }
2770
2771 static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
2772                                    unsigned long arg)
2773 {
2774         return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
2775 }
2776
2777 /*
2778  * All files which have been polled are linked to RB tree
2779  * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
2780  * find the matching one.
2781  */
2782 static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
2783                                               struct rb_node **parent_out)
2784 {
2785         struct rb_node **link = &fc->polled_files.rb_node;
2786         struct rb_node *last = NULL;
2787
2788         while (*link) {
2789                 struct fuse_file *ff;
2790
2791                 last = *link;
2792                 ff = rb_entry(last, struct fuse_file, polled_node);
2793
2794                 if (kh < ff->kh)
2795                         link = &last->rb_left;
2796                 else if (kh > ff->kh)
2797                         link = &last->rb_right;
2798                 else
2799                         return link;
2800         }
2801
2802         if (parent_out)
2803                 *parent_out = last;
2804         return link;
2805 }
2806
2807 /*
2808  * The file is about to be polled.  Make sure it's on the polled_files
2809  * RB tree.  Note that files once added to the polled_files tree are
2810  * not removed before the file is released.  This is because a file
2811  * polled once is likely to be polled again.
2812  */
2813 static void fuse_register_polled_file(struct fuse_conn *fc,
2814                                       struct fuse_file *ff)
2815 {
2816         spin_lock(&fc->lock);
2817         if (RB_EMPTY_NODE(&ff->polled_node)) {
2818                 struct rb_node **link, *uninitialized_var(parent);
2819
2820                 link = fuse_find_polled_node(fc, ff->kh, &parent);
2821                 BUG_ON(*link);
2822                 rb_link_node(&ff->polled_node, parent, link);
2823                 rb_insert_color(&ff->polled_node, &fc->polled_files);
2824         }
2825         spin_unlock(&fc->lock);
2826 }
2827
2828 __poll_t fuse_file_poll(struct file *file, poll_table *wait)
2829 {
2830         struct fuse_file *ff = file->private_data;
2831         struct fuse_conn *fc = ff->fc;
2832         struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
2833         struct fuse_poll_out outarg;
2834         FUSE_ARGS(args);
2835         int err;
2836
2837         if (fc->no_poll)
2838                 return DEFAULT_POLLMASK;
2839
2840         poll_wait(file, &ff->poll_wait, wait);
2841         inarg.events = mangle_poll(poll_requested_events(wait));
2842
2843         /*
2844          * Ask for notification iff there's someone waiting for it.
2845          * The client may ignore the flag and always notify.
2846          */
2847         if (waitqueue_active(&ff->poll_wait)) {
2848                 inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
2849                 fuse_register_polled_file(fc, ff);
2850         }
2851
2852         args.in.h.opcode = FUSE_POLL;
2853         args.in.h.nodeid = ff->nodeid;
2854         args.in.numargs = 1;
2855         args.in.args[0].size = sizeof(inarg);
2856         args.in.args[0].value = &inarg;
2857         args.out.numargs = 1;
2858         args.out.args[0].size = sizeof(outarg);
2859         args.out.args[0].value = &outarg;
2860         err = fuse_simple_request(fc, &args);
2861
2862         if (!err)
2863                 return demangle_poll(outarg.revents);
2864         if (err == -ENOSYS) {
2865                 fc->no_poll = 1;
2866                 return DEFAULT_POLLMASK;
2867         }
2868         return EPOLLERR;
2869 }
2870 EXPORT_SYMBOL_GPL(fuse_file_poll);
2871
2872 /*
2873  * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
2874  * wakes up the poll waiters.
2875  */
2876 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
2877                             struct fuse_notify_poll_wakeup_out *outarg)
2878 {
2879         u64 kh = outarg->kh;
2880         struct rb_node **link;
2881
2882         spin_lock(&fc->lock);
2883
2884         link = fuse_find_polled_node(fc, kh, NULL);
2885         if (*link) {
2886                 struct fuse_file *ff;
2887
2888                 ff = rb_entry(*link, struct fuse_file, polled_node);
2889                 wake_up_interruptible_sync(&ff->poll_wait);
2890         }
2891
2892         spin_unlock(&fc->lock);
2893         return 0;
2894 }
2895
2896 static void fuse_do_truncate(struct file *file)
2897 {
2898         struct inode *inode = file->f_mapping->host;
2899         struct iattr attr;
2900
2901         attr.ia_valid = ATTR_SIZE;
2902         attr.ia_size = i_size_read(inode);
2903
2904         attr.ia_file = file;
2905         attr.ia_valid |= ATTR_FILE;
2906
2907         fuse_do_setattr(file_dentry(file), &attr, file);
2908 }
2909
2910 static inline loff_t fuse_round_up(struct fuse_conn *fc, loff_t off)
2911 {
2912         return round_up(off, fc->max_pages << PAGE_SHIFT);
2913 }
2914
2915 static ssize_t
2916 fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
2917 {
2918         DECLARE_COMPLETION_ONSTACK(wait);
2919         ssize_t ret = 0;
2920         struct file *file = iocb->ki_filp;
2921         struct fuse_file *ff = file->private_data;
2922         bool async_dio = ff->fc->async_dio;
2923         loff_t pos = 0;
2924         struct inode *inode;
2925         loff_t i_size;
2926         size_t count = iov_iter_count(iter);
2927         loff_t offset = iocb->ki_pos;
2928         struct fuse_io_priv *io;
2929
2930         pos = offset;
2931         inode = file->f_mapping->host;
2932         i_size = i_size_read(inode);
2933
2934         if ((iov_iter_rw(iter) == READ) && (offset > i_size))
2935                 return 0;
2936
2937         /* optimization for short read */
2938         if (async_dio && iov_iter_rw(iter) != WRITE && offset + count > i_size) {
2939                 if (offset >= i_size)
2940                         return 0;
2941                 iov_iter_truncate(iter, fuse_round_up(ff->fc, i_size - offset));
2942                 count = iov_iter_count(iter);
2943         }
2944
2945         io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
2946         if (!io)
2947                 return -ENOMEM;
2948         spin_lock_init(&io->lock);
2949         kref_init(&io->refcnt);
2950         io->reqs = 1;
2951         io->bytes = -1;
2952         io->size = 0;
2953         io->offset = offset;
2954         io->write = (iov_iter_rw(iter) == WRITE);
2955         io->err = 0;
2956         /*
2957          * By default, we want to optimize all I/Os with async request
2958          * submission to the client filesystem if supported.
2959          */
2960         io->async = async_dio;
2961         io->iocb = iocb;
2962         io->blocking = is_sync_kiocb(iocb);
2963
2964         /*
2965          * We cannot asynchronously extend the size of a file.
2966          * In such case the aio will behave exactly like sync io.
2967          */
2968         if ((offset + count > i_size) && iov_iter_rw(iter) == WRITE)
2969                 io->blocking = true;
2970
2971         if (io->async && io->blocking) {
2972                 /*
2973                  * Additional reference to keep io around after
2974                  * calling fuse_aio_complete()
2975                  */
2976                 kref_get(&io->refcnt);
2977                 io->done = &wait;
2978         }
2979
2980         if (iov_iter_rw(iter) == WRITE) {
2981                 ret = fuse_direct_io(io, iter, &pos, FUSE_DIO_WRITE);
2982                 fuse_invalidate_attr(inode);
2983         } else {
2984                 ret = __fuse_direct_read(io, iter, &pos);
2985         }
2986
2987         if (io->async) {
2988                 bool blocking = io->blocking;
2989
2990                 fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
2991
2992                 /* we have a non-extending, async request, so return */
2993                 if (!blocking)
2994                         return -EIOCBQUEUED;
2995
2996                 wait_for_completion(&wait);
2997                 ret = fuse_get_res_by_io(io);
2998         }
2999
3000         kref_put(&io->refcnt, fuse_io_release);
3001
3002         if (iov_iter_rw(iter) == WRITE) {
3003                 if (ret > 0)
3004                         fuse_write_update_size(inode, pos);
3005                 else if (ret < 0 && offset + count > i_size)
3006                         fuse_do_truncate(file);
3007         }
3008
3009         return ret;
3010 }
3011
3012 static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
3013                                 loff_t length)
3014 {
3015         struct fuse_file *ff = file->private_data;
3016         struct inode *inode = file_inode(file);
3017         struct fuse_inode *fi = get_fuse_inode(inode);
3018         struct fuse_conn *fc = ff->fc;
3019         FUSE_ARGS(args);
3020         struct fuse_fallocate_in inarg = {
3021                 .fh = ff->fh,
3022                 .offset = offset,
3023                 .length = length,
3024                 .mode = mode
3025         };
3026         int err;
3027         bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) ||
3028                            (mode & FALLOC_FL_PUNCH_HOLE);
3029
3030         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
3031                 return -EOPNOTSUPP;
3032
3033         if (fc->no_fallocate)
3034                 return -EOPNOTSUPP;
3035
3036         if (lock_inode) {
3037                 inode_lock(inode);
3038                 if (mode & FALLOC_FL_PUNCH_HOLE) {
3039                         loff_t endbyte = offset + length - 1;
3040                         err = filemap_write_and_wait_range(inode->i_mapping,
3041                                                            offset, endbyte);
3042                         if (err)
3043                                 goto out;
3044
3045                         fuse_sync_writes(inode);
3046                 }
3047         }
3048
3049         if (!(mode & FALLOC_FL_KEEP_SIZE))
3050                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3051
3052         args.in.h.opcode = FUSE_FALLOCATE;
3053         args.in.h.nodeid = ff->nodeid;
3054         args.in.numargs = 1;
3055         args.in.args[0].size = sizeof(inarg);
3056         args.in.args[0].value = &inarg;
3057         err = fuse_simple_request(fc, &args);
3058         if (err == -ENOSYS) {
3059                 fc->no_fallocate = 1;
3060                 err = -EOPNOTSUPP;
3061         }
3062         if (err)
3063                 goto out;
3064
3065         /* we could have extended the file */
3066         if (!(mode & FALLOC_FL_KEEP_SIZE)) {
3067                 bool changed = fuse_write_update_size(inode, offset + length);
3068
3069                 if (changed && fc->writeback_cache)
3070                         file_update_time(file);
3071         }
3072
3073         if (mode & FALLOC_FL_PUNCH_HOLE)
3074                 truncate_pagecache_range(inode, offset, offset + length - 1);
3075
3076         fuse_invalidate_attr(inode);
3077
3078 out:
3079         if (!(mode & FALLOC_FL_KEEP_SIZE))
3080                 clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3081
3082         if (lock_inode)
3083                 inode_unlock(inode);
3084
3085         return err;
3086 }
3087
3088 static ssize_t fuse_copy_file_range(struct file *file_in, loff_t pos_in,
3089                                     struct file *file_out, loff_t pos_out,
3090                                     size_t len, unsigned int flags)
3091 {
3092         struct fuse_file *ff_in = file_in->private_data;
3093         struct fuse_file *ff_out = file_out->private_data;
3094         struct inode *inode_out = file_inode(file_out);
3095         struct fuse_inode *fi_out = get_fuse_inode(inode_out);
3096         struct fuse_conn *fc = ff_in->fc;
3097         FUSE_ARGS(args);
3098         struct fuse_copy_file_range_in inarg = {
3099                 .fh_in = ff_in->fh,
3100                 .off_in = pos_in,
3101                 .nodeid_out = ff_out->nodeid,
3102                 .fh_out = ff_out->fh,
3103                 .off_out = pos_out,
3104                 .len = len,
3105                 .flags = flags
3106         };
3107         struct fuse_write_out outarg;
3108         ssize_t err;
3109         /* mark unstable when write-back is not used, and file_out gets
3110          * extended */
3111         bool is_unstable = (!fc->writeback_cache) &&
3112                            ((pos_out + len) > inode_out->i_size);
3113
3114         if (fc->no_copy_file_range)
3115                 return -EOPNOTSUPP;
3116
3117         inode_lock(inode_out);
3118
3119         if (fc->writeback_cache) {
3120                 err = filemap_write_and_wait_range(inode_out->i_mapping,
3121                                                    pos_out, pos_out + len);
3122                 if (err)
3123                         goto out;
3124
3125                 fuse_sync_writes(inode_out);
3126         }
3127
3128         if (is_unstable)
3129                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
3130
3131         args.in.h.opcode = FUSE_COPY_FILE_RANGE;
3132         args.in.h.nodeid = ff_in->nodeid;
3133         args.in.numargs = 1;
3134         args.in.args[0].size = sizeof(inarg);
3135         args.in.args[0].value = &inarg;
3136         args.out.numargs = 1;
3137         args.out.args[0].size = sizeof(outarg);
3138         args.out.args[0].value = &outarg;
3139         err = fuse_simple_request(fc, &args);
3140         if (err == -ENOSYS) {
3141                 fc->no_copy_file_range = 1;
3142                 err = -EOPNOTSUPP;
3143         }
3144         if (err)
3145                 goto out;
3146
3147         if (fc->writeback_cache) {
3148                 fuse_write_update_size(inode_out, pos_out + outarg.size);
3149                 file_update_time(file_out);
3150         }
3151
3152         fuse_invalidate_attr(inode_out);
3153
3154         err = outarg.size;
3155 out:
3156         if (is_unstable)
3157                 clear_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
3158
3159         inode_unlock(inode_out);
3160
3161         return err;
3162 }
3163
3164 static const struct file_operations fuse_file_operations = {
3165         .llseek         = fuse_file_llseek,
3166         .read_iter      = fuse_file_read_iter,
3167         .write_iter     = fuse_file_write_iter,
3168         .mmap           = fuse_file_mmap,
3169         .open           = fuse_open,
3170         .flush          = fuse_flush,
3171         .release        = fuse_release,
3172         .fsync          = fuse_fsync,
3173         .lock           = fuse_file_lock,
3174         .flock          = fuse_file_flock,
3175         .splice_read    = generic_file_splice_read,
3176         .splice_write   = iter_file_splice_write,
3177         .unlocked_ioctl = fuse_file_ioctl,
3178         .compat_ioctl   = fuse_file_compat_ioctl,
3179         .poll           = fuse_file_poll,
3180         .fallocate      = fuse_file_fallocate,
3181         .copy_file_range = fuse_copy_file_range,
3182 };
3183
3184 static const struct address_space_operations fuse_file_aops  = {
3185         .readpage       = fuse_readpage,
3186         .writepage      = fuse_writepage,
3187         .writepages     = fuse_writepages,
3188         .launder_page   = fuse_launder_page,
3189         .readpages      = fuse_readpages,
3190         .set_page_dirty = __set_page_dirty_nobuffers,
3191         .bmap           = fuse_bmap,
3192         .direct_IO      = fuse_direct_IO,
3193         .write_begin    = fuse_write_begin,
3194         .write_end      = fuse_write_end,
3195 };
3196
3197 void fuse_init_file_inode(struct inode *inode)
3198 {
3199         struct fuse_inode *fi = get_fuse_inode(inode);
3200
3201         inode->i_fop = &fuse_file_operations;
3202         inode->i_data.a_ops = &fuse_file_aops;
3203
3204         INIT_LIST_HEAD(&fi->write_files);
3205         INIT_LIST_HEAD(&fi->queued_writes);
3206         fi->writectr = 0;
3207         init_waitqueue_head(&fi->page_waitq);
3208         INIT_LIST_HEAD(&fi->writepages);
3209 }