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 #include <linux/fs.h>
  22
  23 static struct page **fuse_pages_alloc(unsigned int npages, gfp_t flags,
  24                                       struct fuse_page_desc **desc)
  25 {
  26         struct page **pages;
  27
  28         pages = kzalloc(npages * (sizeof(struct page *) +
  29                                   sizeof(struct fuse_page_desc)), flags);
  30         *desc = (void *) (pages + npages);
  31
  32         return pages;
  33 }
  34
  35 static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
  36                           int opcode, struct fuse_open_out *outargp)
  37 {
  38         struct fuse_open_in inarg;
  39         FUSE_ARGS(args);
  40
  41         memset(&inarg, 0, sizeof(inarg));
  42         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
  43         if (!fc->atomic_o_trunc)
  44                 inarg.flags &= ~O_TRUNC;
  45         args.opcode = opcode;
  46         args.nodeid = nodeid;
  47         args.in_numargs = 1;
  48         args.in_args[0].size = sizeof(inarg);
  49         args.in_args[0].value = &inarg;
  50         args.out_numargs = 1;
  51         args.out_args[0].size = sizeof(*outargp);
  52         args.out_args[0].value = outargp;
  53
  54         return fuse_simple_request(fc, &args);
  55 }
  56
  57 struct fuse_release_args {
  58         struct fuse_args args;
  59         struct fuse_release_in inarg;
  60         struct inode *inode;
  61 };
  62
  63 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
  64 {
  65         struct fuse_file *ff;
  66
  67         ff = kzalloc(sizeof(struct fuse_file), GFP_KERNEL_ACCOUNT);
  68         if (unlikely(!ff))
  69                 return NULL;
  70
  71         ff->fc = fc;
  72         ff->release_args = kzalloc(sizeof(*ff->release_args),
  73                                    GFP_KERNEL_ACCOUNT);
  74         if (!ff->release_args) {
  75                 kfree(ff);
  76                 return NULL;
  77         }
  78
  79         INIT_LIST_HEAD(&ff->write_entry);
  80         mutex_init(&ff->readdir.lock);
  81         refcount_set(&ff->count, 1);
  82         RB_CLEAR_NODE(&ff->polled_node);
  83         init_waitqueue_head(&ff->poll_wait);
  84
  85         ff->kh = atomic64_inc_return(&fc->khctr);
  86
  87         return ff;
  88 }
  89
  90 void fuse_file_free(struct fuse_file *ff)
  91 {
  92         kfree(ff->release_args);
  93         mutex_destroy(&ff->readdir.lock);
  94         kfree(ff);
  95 }
  96
  97 static struct fuse_file *fuse_file_get(struct fuse_file *ff)
  98 {
  99         refcount_inc(&ff->count);
 100         return ff;
 101 }
 102
 103 static void fuse_release_end(struct fuse_conn *fc, struct fuse_args *args,
 104                              int error)
 105 {
 106         struct fuse_release_args *ra = container_of(args, typeof(*ra), args);
 107
 108         iput(ra->inode);
 109         kfree(ra);
 110 }
 111
 112 static void fuse_file_put(struct fuse_file *ff, bool sync, bool isdir)
 113 {
 114         if (refcount_dec_and_test(&ff->count)) {
 115                 struct fuse_args *args = &ff->release_args->args;
 116
 117                 if (isdir ? ff->fc->no_opendir : ff->fc->no_open) {
 118                         /* Do nothing when client does not implement 'open' */
 119                         fuse_release_end(ff->fc, args, 0);
 120                 } else if (sync) {
 121                         fuse_simple_request(ff->fc, args);
 122                         fuse_release_end(ff->fc, args, 0);
 123                 } else {
 124                         args->end = fuse_release_end;
 125                         if (fuse_simple_background(ff->fc, args,
 126                                                    GFP_KERNEL | __GFP_NOFAIL))
 127                                 fuse_release_end(ff->fc, args, -ENOTCONN);
 128                 }
 129                 kfree(ff);
 130         }
 131 }
 132
 133 int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 134                  bool isdir)
 135 {
 136         struct fuse_file *ff;
 137         int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
 138
 139         ff = fuse_file_alloc(fc);
 140         if (!ff)
 141                 return -ENOMEM;
 142
 143         ff->fh = 0;
 144         /* Default for no-open */
 145         ff->open_flags = FOPEN_KEEP_CACHE | (isdir ? FOPEN_CACHE_DIR : 0);
 146         if (isdir ? !fc->no_opendir : !fc->no_open) {
 147                 struct fuse_open_out outarg;
 148                 int err;
 149
 150                 err = fuse_send_open(fc, nodeid, file, opcode, &outarg);
 151                 if (!err) {
 152                         ff->fh = outarg.fh;
 153                         ff->open_flags = outarg.open_flags;
 154
 155                 } else if (err != -ENOSYS) {
 156                         fuse_file_free(ff);
 157                         return err;
 158                 } else {
 159                         if (isdir)
 160                                 fc->no_opendir = 1;
 161                         else
 162                                 fc->no_open = 1;
 163                 }
 164         }
 165
 166         if (isdir)
 167                 ff->open_flags &= ~FOPEN_DIRECT_IO;
 168
 169         ff->nodeid = nodeid;
 170         file->private_data = ff;
 171
 172         return 0;
 173 }
 174 EXPORT_SYMBOL_GPL(fuse_do_open);
 175
 176 static void fuse_link_write_file(struct file *file)
 177 {
 178         struct inode *inode = file_inode(file);
 179         struct fuse_inode *fi = get_fuse_inode(inode);
 180         struct fuse_file *ff = file->private_data;
 181         /*
 182          * file may be written through mmap, so chain it onto the
 183          * inodes's write_file list
 184          */
 185         spin_lock(&fi->lock);
 186         if (list_empty(&ff->write_entry))
 187                 list_add(&ff->write_entry, &fi->write_files);
 188         spin_unlock(&fi->lock);
 189 }
 190
 191 void fuse_finish_open(struct inode *inode, struct file *file)
 192 {
 193         struct fuse_file *ff = file->private_data;
 194         struct fuse_conn *fc = get_fuse_conn(inode);
 195
 196         if (ff->open_flags & FOPEN_STREAM)
 197                 stream_open(inode, file);
 198         else if (ff->open_flags & FOPEN_NONSEEKABLE)
 199                 nonseekable_open(inode, file);
 200
 201         if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {
 202                 struct fuse_inode *fi = get_fuse_inode(inode);
 203
 204                 spin_lock(&fi->lock);
 205                 fi->attr_version = atomic64_inc_return(&fc->attr_version);
 206                 i_size_write(inode, 0);
 207                 spin_unlock(&fi->lock);
 208                 truncate_pagecache(inode, 0);
 209                 fuse_invalidate_attr(inode);
 210                 if (fc->writeback_cache)
 211                         file_update_time(file);
 212         } else if (!(ff->open_flags & FOPEN_KEEP_CACHE)) {
 213                 invalidate_inode_pages2(inode->i_mapping);
 214         }
 215
 216         if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)
 217                 fuse_link_write_file(file);
 218 }
 219
 220 int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
 221 {
 222         struct fuse_conn *fc = get_fuse_conn(inode);
 223         int err;
 224         bool is_wb_truncate = (file->f_flags & O_TRUNC) &&
 225                           fc->atomic_o_trunc &&
 226                           fc->writeback_cache;
 227
 228         if (fuse_is_bad(inode))
 229                 return -EIO;
 230
 231         err = generic_file_open(inode, file);
 232         if (err)
 233                 return err;
 234
 235         if (is_wb_truncate) {
 236                 inode_lock(inode);
 237                 fuse_set_nowrite(inode);
 238         }
 239
 240         err = fuse_do_open(fc, get_node_id(inode), file, isdir);
 241
 242         if (!err)
 243                 fuse_finish_open(inode, file);
 244
 245         if (is_wb_truncate) {
 246                 fuse_release_nowrite(inode);
 247                 inode_unlock(inode);
 248         }
 249
 250         return err;
 251 }
 252
 253 static void fuse_prepare_release(struct fuse_inode *fi, struct fuse_file *ff,
 254                                  int flags, int opcode)
 255 {
 256         struct fuse_conn *fc = ff->fc;
 257         struct fuse_release_args *ra = ff->release_args;
 258
 259         /* Inode is NULL on error path of fuse_create_open() */
 260         if (likely(fi)) {
 261                 spin_lock(&fi->lock);
 262                 list_del(&ff->write_entry);
 263                 spin_unlock(&fi->lock);
 264         }
 265         spin_lock(&fc->lock);
 266         if (!RB_EMPTY_NODE(&ff->polled_node))
 267                 rb_erase(&ff->polled_node, &fc->polled_files);
 268         spin_unlock(&fc->lock);
 269
 270         wake_up_interruptible_all(&ff->poll_wait);
 271
 272         ra->inarg.fh = ff->fh;
 273         ra->inarg.flags = flags;
 274         ra->args.in_numargs = 1;
 275         ra->args.in_args[0].size = sizeof(struct fuse_release_in);
 276         ra->args.in_args[0].value = &ra->inarg;
 277         ra->args.opcode = opcode;
 278         ra->args.nodeid = ff->nodeid;
 279         ra->args.force = true;
 280         ra->args.nocreds = true;
 281 }
 282
 283 void fuse_release_common(struct file *file, bool isdir)
 284 {
 285         struct fuse_inode *fi = get_fuse_inode(file_inode(file));
 286         struct fuse_file *ff = file->private_data;
 287         struct fuse_release_args *ra = ff->release_args;
 288         int opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
 289
 290         fuse_prepare_release(fi, ff, file->f_flags, opcode);
 291
 292         if (ff->flock) {
 293                 ra->inarg.release_flags |= FUSE_RELEASE_FLOCK_UNLOCK;
 294                 ra->inarg.lock_owner = fuse_lock_owner_id(ff->fc,
 295                                                           (fl_owner_t) file);
 296         }
 297         /* Hold inode until release is finished */
 298         ra->inode = igrab(file_inode(file));
 299
 300         /*
 301          * Normally this will send the RELEASE request, however if
 302          * some asynchronous READ or WRITE requests are outstanding,
 303          * the sending will be delayed.
 304          *
 305          * Make the release synchronous if this is a fuseblk mount,
 306          * synchronous RELEASE is allowed (and desirable) in this case
 307          * because the server can be trusted not to screw up.
 308          */
 309         fuse_file_put(ff, ff->fc->destroy, isdir);
 310 }
 311
 312 static int fuse_open(struct inode *inode, struct file *file)
 313 {
 314         return fuse_open_common(inode, file, false);
 315 }
 316
 317 static int fuse_release(struct inode *inode, struct file *file)
 318 {
 319         struct fuse_conn *fc = get_fuse_conn(inode);
 320
 321         /* see fuse_vma_close() for !writeback_cache case */
 322         if (fc->writeback_cache)
 323                 write_inode_now(inode, 1);
 324
 325         fuse_release_common(file, false);
 326
 327         /* return value is ignored by VFS */
 328         return 0;
 329 }
 330
 331 void fuse_sync_release(struct fuse_inode *fi, struct fuse_file *ff, int flags)
 332 {
 333         WARN_ON(refcount_read(&ff->count) > 1);
 334         fuse_prepare_release(fi, ff, flags, FUSE_RELEASE);
 335         /*
 336          * iput(NULL) is a no-op and since the refcount is 1 and everything's
 337          * synchronous, we are fine with not doing igrab() here"
 338          */
 339         fuse_file_put(ff, true, false);
 340 }
 341 EXPORT_SYMBOL_GPL(fuse_sync_release);
 342
 343 /*
 344  * Scramble the ID space with XTEA, so that the value of the files_struct
 345  * pointer is not exposed to userspace.
 346  */
 347 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
 348 {
 349         u32 *k = fc->scramble_key;
 350         u64 v = (unsigned long) id;
 351         u32 v0 = v;
 352         u32 v1 = v >> 32;
 353         u32 sum = 0;
 354         int i;
 355
 356         for (i = 0; i < 32; i++) {
 357                 v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
 358                 sum += 0x9E3779B9;
 359                 v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
 360         }
 361
 362         return (u64) v0 + ((u64) v1 << 32);
 363 }
 364
 365 struct fuse_writepage_args {
 366         struct fuse_io_args ia;
 367         struct list_head writepages_entry;
 368         struct list_head queue_entry;
 369         struct fuse_writepage_args *next;
 370         struct inode *inode;
 371 };
 372
 373 static struct fuse_writepage_args *fuse_find_writeback(struct fuse_inode *fi,
 374                                             pgoff_t idx_from, pgoff_t idx_to)
 375 {
 376         struct fuse_writepage_args *wpa;
 377
 378         list_for_each_entry(wpa, &fi->writepages, writepages_entry) {
 379                 pgoff_t curr_index;
 380
 381                 WARN_ON(get_fuse_inode(wpa->inode) != fi);
 382                 curr_index = wpa->ia.write.in.offset >> PAGE_SHIFT;
 383                 if (idx_from < curr_index + wpa->ia.ap.num_pages &&
 384                     curr_index <= idx_to) {
 385                         return wpa;
 386                 }
 387         }
 388         return NULL;
 389 }
 390
 391 /*
 392  * Check if any page in a range is under writeback
 393  *
 394  * This is currently done by walking the list of writepage requests
 395  * for the inode, which can be pretty inefficient.
 396  */
 397 static bool fuse_range_is_writeback(struct inode *inode, pgoff_t idx_from,
 398                                    pgoff_t idx_to)
 399 {
 400         struct fuse_inode *fi = get_fuse_inode(inode);
 401         bool found;
 402
 403         spin_lock(&fi->lock);
 404         found = fuse_find_writeback(fi, idx_from, idx_to);
 405         spin_unlock(&fi->lock);
 406
 407         return found;
 408 }
 409
 410 static inline bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
 411 {
 412         return fuse_range_is_writeback(inode, index, index);
 413 }
 414
 415 /*
 416  * Wait for page writeback to be completed.
 417  *
 418  * Since fuse doesn't rely on the VM writeback tracking, this has to
 419  * use some other means.
 420  */
 421 static void fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
 422 {
 423         struct fuse_inode *fi = get_fuse_inode(inode);
 424
 425         wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
 426 }
 427
 428 /*
 429  * Wait for all pending writepages on the inode to finish.
 430  *
 431  * This is currently done by blocking further writes with FUSE_NOWRITE
 432  * and waiting for all sent writes to complete.
 433  *
 434  * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
 435  * could conflict with truncation.
 436  */
 437 static void fuse_sync_writes(struct inode *inode)
 438 {
 439         fuse_set_nowrite(inode);
 440         fuse_release_nowrite(inode);
 441 }
 442
 443 static int fuse_flush(struct file *file, fl_owner_t id)
 444 {
 445         struct inode *inode = file_inode(file);
 446         struct fuse_conn *fc = get_fuse_conn(inode);
 447         struct fuse_file *ff = file->private_data;
 448         struct fuse_flush_in inarg;
 449         FUSE_ARGS(args);
 450         int err;
 451
 452         if (fuse_is_bad(inode))
 453                 return -EIO;
 454
 455         if (fc->no_flush)
 456                 return 0;
 457
 458         err = write_inode_now(inode, 1);
 459         if (err)
 460                 return err;
 461
 462         inode_lock(inode);
 463         fuse_sync_writes(inode);
 464         inode_unlock(inode);
 465
 466         err = filemap_check_errors(file->f_mapping);
 467         if (err)
 468                 return err;
 469
 470         memset(&inarg, 0, sizeof(inarg));
 471         inarg.fh = ff->fh;
 472         inarg.lock_owner = fuse_lock_owner_id(fc, id);
 473         args.opcode = FUSE_FLUSH;
 474         args.nodeid = get_node_id(inode);
 475         args.in_numargs = 1;
 476         args.in_args[0].size = sizeof(inarg);
 477         args.in_args[0].value = &inarg;
 478         args.force = true;
 479
 480         err = fuse_simple_request(fc, &args);
 481         if (err == -ENOSYS) {
 482                 fc->no_flush = 1;
 483                 err = 0;
 484         }
 485         return err;
 486 }
 487
 488 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
 489                       int datasync, int opcode)
 490 {
 491         struct inode *inode = file->f_mapping->host;
 492         struct fuse_conn *fc = get_fuse_conn(inode);
 493         struct fuse_file *ff = file->private_data;
 494         FUSE_ARGS(args);
 495         struct fuse_fsync_in inarg;
 496
 497         memset(&inarg, 0, sizeof(inarg));
 498         inarg.fh = ff->fh;
 499         inarg.fsync_flags = datasync ? FUSE_FSYNC_FDATASYNC : 0;
 500         args.opcode = opcode;
 501         args.nodeid = get_node_id(inode);
 502         args.in_numargs = 1;
 503         args.in_args[0].size = sizeof(inarg);
 504         args.in_args[0].value = &inarg;
 505         return fuse_simple_request(fc, &args);
 506 }
 507
 508 static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 509                       int datasync)
 510 {
 511         struct inode *inode = file->f_mapping->host;
 512         struct fuse_conn *fc = get_fuse_conn(inode);
 513         int err;
 514
 515         if (fuse_is_bad(inode))
 516                 return -EIO;
 517
 518         inode_lock(inode);
 519
 520         /*
 521          * Start writeback against all dirty pages of the inode, then
 522          * wait for all outstanding writes, before sending the FSYNC
 523          * request.
 524          */
 525         err = file_write_and_wait_range(file, start, end);
 526         if (err)
 527                 goto out;
 528
 529         fuse_sync_writes(inode);
 530
 531         /*
 532          * Due to implementation of fuse writeback
 533          * file_write_and_wait_range() does not catch errors.
 534          * We have to do this directly after fuse_sync_writes()
 535          */
 536         err = file_check_and_advance_wb_err(file);
 537         if (err)
 538                 goto out;
 539
 540         err = sync_inode_metadata(inode, 1);
 541         if (err)
 542                 goto out;
 543
 544         if (fc->no_fsync)
 545                 goto out;
 546
 547         err = fuse_fsync_common(file, start, end, datasync, FUSE_FSYNC);
 548         if (err == -ENOSYS) {
 549                 fc->no_fsync = 1;
 550                 err = 0;
 551         }
 552 out:
 553         inode_unlock(inode);
 554
 555         return err;
 556 }
 557
 558 void fuse_read_args_fill(struct fuse_io_args *ia, struct file *file, loff_t pos,
 559                          size_t count, int opcode)
 560 {
 561         struct fuse_file *ff = file->private_data;
 562         struct fuse_args *args = &ia->ap.args;
 563
 564         ia->read.in.fh = ff->fh;
 565         ia->read.in.offset = pos;
 566         ia->read.in.size = count;
 567         ia->read.in.flags = file->f_flags;
 568         args->opcode = opcode;
 569         args->nodeid = ff->nodeid;
 570         args->in_numargs = 1;
 571         args->in_args[0].size = sizeof(ia->read.in);
 572         args->in_args[0].value = &ia->read.in;
 573         args->out_argvar = true;
 574         args->out_numargs = 1;
 575         args->out_args[0].size = count;
 576 }
 577
 578 static void fuse_release_user_pages(struct fuse_args_pages *ap,
 579                                     bool should_dirty)
 580 {
 581         unsigned int i;
 582
 583         for (i = 0; i < ap->num_pages; i++) {
 584                 if (should_dirty)
 585                         set_page_dirty_lock(ap->pages[i]);
 586                 put_page(ap->pages[i]);
 587         }
 588 }
 589
 590 static void fuse_io_release(struct kref *kref)
 591 {
 592         kfree(container_of(kref, struct fuse_io_priv, refcnt));
 593 }
 594
 595 static ssize_t fuse_get_res_by_io(struct fuse_io_priv *io)
 596 {
 597         if (io->err)
 598                 return io->err;
 599
 600         if (io->bytes >= 0 && io->write)
 601                 return -EIO;
 602
 603         return io->bytes < 0 ? io->size : io->bytes;
 604 }
 605
 606 /**
 607  * In case of short read, the caller sets 'pos' to the position of
 608  * actual end of fuse request in IO request. Otherwise, if bytes_requested
 609  * == bytes_transferred or rw == WRITE, the caller sets 'pos' to -1.
 610  *
 611  * An example:
 612  * User requested DIO read of 64K. It was splitted into two 32K fuse requests,
 613  * both submitted asynchronously. The first of them was ACKed by userspace as
 614  * fully completed (req->out.args[0].size == 32K) resulting in pos == -1. The
 615  * second request was ACKed as short, e.g. only 1K was read, resulting in
 616  * pos == 33K.
 617  *
 618  * Thus, when all fuse requests are completed, the minimal non-negative 'pos'
 619  * will be equal to the length of the longest contiguous fragment of
 620  * transferred data starting from the beginning of IO request.
 621  */
 622 static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
 623 {
 624         int left;
 625
 626         spin_lock(&io->lock);
 627         if (err)
 628                 io->err = io->err ? : err;
 629         else if (pos >= 0 && (io->bytes < 0 || pos < io->bytes))
 630                 io->bytes = pos;
 631
 632         left = --io->reqs;
 633         if (!left && io->blocking)
 634                 complete(io->done);
 635         spin_unlock(&io->lock);
 636
 637         if (!left && !io->blocking) {
 638                 ssize_t res = fuse_get_res_by_io(io);
 639
 640                 if (res >= 0) {
 641                         struct inode *inode = file_inode(io->iocb->ki_filp);
 642                         struct fuse_conn *fc = get_fuse_conn(inode);
 643                         struct fuse_inode *fi = get_fuse_inode(inode);
 644
 645                         spin_lock(&fi->lock);
 646                         fi->attr_version = atomic64_inc_return(&fc->attr_version);
 647                         spin_unlock(&fi->lock);
 648                 }
 649
 650                 io->iocb->ki_complete(io->iocb, res, 0);
 651         }
 652
 653         kref_put(&io->refcnt, fuse_io_release);
 654 }
 655
 656 static struct fuse_io_args *fuse_io_alloc(struct fuse_io_priv *io,
 657                                           unsigned int npages)
 658 {
 659         struct fuse_io_args *ia;
 660
 661         ia = kzalloc(sizeof(*ia), GFP_KERNEL);
 662         if (ia) {
 663                 ia->io = io;
 664                 ia->ap.pages = fuse_pages_alloc(npages, GFP_KERNEL,
 665                                                 &ia->ap.descs);
 666                 if (!ia->ap.pages) {
 667                         kfree(ia);
 668                         ia = NULL;
 669                 }
 670         }
 671         return ia;
 672 }
 673
 674 static void fuse_io_free(struct fuse_io_args *ia)
 675 {
 676         kfree(ia->ap.pages);
 677         kfree(ia);
 678 }
 679
 680 static void fuse_aio_complete_req(struct fuse_conn *fc, struct fuse_args *args,
 681                                   int err)
 682 {
 683         struct fuse_io_args *ia = container_of(args, typeof(*ia), ap.args);
 684         struct fuse_io_priv *io = ia->io;
 685         ssize_t pos = -1;
 686
 687         fuse_release_user_pages(&ia->ap, io->should_dirty);
 688
 689         if (err) {
 690                 /* Nothing */
 691         } else if (io->write) {
 692                 if (ia->write.out.size > ia->write.in.size) {
 693                         err = -EIO;
 694                 } else if (ia->write.in.size != ia->write.out.size) {
 695                         pos = ia->write.in.offset - io->offset +
 696                                 ia->write.out.size;
 697                 }
 698         } else {
 699                 u32 outsize = args->out_args[0].size;
 700
 701                 if (ia->read.in.size != outsize)
 702                         pos = ia->read.in.offset - io->offset + outsize;
 703         }
 704
 705         fuse_aio_complete(io, err, pos);
 706         fuse_io_free(ia);
 707 }
 708
 709 static ssize_t fuse_async_req_send(struct fuse_conn *fc,
 710                                    struct fuse_io_args *ia, size_t num_bytes)
 711 {
 712         ssize_t err;
 713         struct fuse_io_priv *io = ia->io;
 714
 715         spin_lock(&io->lock);
 716         kref_get(&io->refcnt);
 717         io->size += num_bytes;
 718         io->reqs++;
 719         spin_unlock(&io->lock);
 720
 721         ia->ap.args.end = fuse_aio_complete_req;
 722         ia->ap.args.may_block = io->should_dirty;
 723         err = fuse_simple_background(fc, &ia->ap.args, GFP_KERNEL);
 724         if (err)
 725                 fuse_aio_complete_req(fc, &ia->ap.args, err);
 726
 727         return num_bytes;
 728 }
 729
 730 static ssize_t fuse_send_read(struct fuse_io_args *ia, loff_t pos, size_t count,
 731                               fl_owner_t owner)
 732 {
 733         struct file *file = ia->io->iocb->ki_filp;
 734         struct fuse_file *ff = file->private_data;
 735         struct fuse_conn *fc = ff->fc;
 736
 737         fuse_read_args_fill(ia, file, pos, count, FUSE_READ);
 738         if (owner != NULL) {
 739                 ia->read.in.read_flags |= FUSE_READ_LOCKOWNER;
 740                 ia->read.in.lock_owner = fuse_lock_owner_id(fc, owner);
 741         }
 742
 743         if (ia->io->async)
 744                 return fuse_async_req_send(fc, ia, count);
 745
 746         return fuse_simple_request(fc, &ia->ap.args);
 747 }
 748
 749 static void fuse_read_update_size(struct inode *inode, loff_t size,
 750                                   u64 attr_ver)
 751 {
 752         struct fuse_conn *fc = get_fuse_conn(inode);
 753         struct fuse_inode *fi = get_fuse_inode(inode);
 754
 755         spin_lock(&fi->lock);
 756         if (attr_ver == fi->attr_version && size < inode->i_size &&
 757             !test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
 758                 fi->attr_version = atomic64_inc_return(&fc->attr_version);
 759                 i_size_write(inode, size);
 760         }
 761         spin_unlock(&fi->lock);
 762 }
 763
 764 static void fuse_short_read(struct inode *inode, u64 attr_ver, size_t num_read,
 765                             struct fuse_args_pages *ap)
 766 {
 767         struct fuse_conn *fc = get_fuse_conn(inode);
 768
 769         if (fc->writeback_cache) {
 770                 /*
 771                  * A hole in a file. Some data after the hole are in page cache,
 772                  * but have not reached the client fs yet. So, the hole is not
 773                  * present there.
 774                  */
 775                 int i;
 776                 int start_idx = num_read >> PAGE_SHIFT;
 777                 size_t off = num_read & (PAGE_SIZE - 1);
 778
 779                 for (i = start_idx; i < ap->num_pages; i++) {
 780                         zero_user_segment(ap->pages[i], off, PAGE_SIZE);
 781                         off = 0;
 782                 }
 783         } else {
 784                 loff_t pos = page_offset(ap->pages[0]) + num_read;
 785                 fuse_read_update_size(inode, pos, attr_ver);
 786         }
 787 }
 788
 789 static int fuse_do_readpage(struct file *file, struct page *page)
 790 {
 791         struct inode *inode = page->mapping->host;
 792         struct fuse_conn *fc = get_fuse_conn(inode);
 793         loff_t pos = page_offset(page);
 794         struct fuse_page_desc desc = { .length = PAGE_SIZE };
 795         struct fuse_io_args ia = {
 796                 .ap.args.page_zeroing = true,
 797                 .ap.args.out_pages = true,
 798                 .ap.num_pages = 1,
 799                 .ap.pages = &page,
 800                 .ap.descs = &desc,
 801         };
 802         ssize_t res;
 803         u64 attr_ver;
 804
 805         /*
 806          * Page writeback can extend beyond the lifetime of the
 807          * page-cache page, so make sure we read a properly synced
 808          * page.
 809          */
 810         fuse_wait_on_page_writeback(inode, page->index);
 811
 812         attr_ver = fuse_get_attr_version(fc);
 813
 814         /* Don't overflow end offset */
 815         if (pos + (desc.length - 1) == LLONG_MAX)
 816                 desc.length--;
 817
 818         fuse_read_args_fill(&ia, file, pos, desc.length, FUSE_READ);
 819         res = fuse_simple_request(fc, &ia.ap.args);
 820         if (res < 0)
 821                 return res;
 822         /*
 823          * Short read means EOF.  If file size is larger, truncate it
 824          */
 825         if (res < desc.length)
 826                 fuse_short_read(inode, attr_ver, res, &ia.ap);
 827
 828         SetPageUptodate(page);
 829
 830         return 0;
 831 }
 832
 833 static int fuse_readpage(struct file *file, struct page *page)
 834 {
 835         struct inode *inode = page->mapping->host;
 836         int err;
 837
 838         err = -EIO;
 839         if (fuse_is_bad(inode))
 840                 goto out;
 841
 842         err = fuse_do_readpage(file, page);
 843         fuse_invalidate_atime(inode);
 844  out:
 845         unlock_page(page);
 846         return err;
 847 }
 848
 849 static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_args *args,
 850                                int err)
 851 {
 852         int i;
 853         struct fuse_io_args *ia = container_of(args, typeof(*ia), ap.args);
 854         struct fuse_args_pages *ap = &ia->ap;
 855         size_t count = ia->read.in.size;
 856         size_t num_read = args->out_args[0].size;
 857         struct address_space *mapping = NULL;
 858
 859         for (i = 0; mapping == NULL && i < ap->num_pages; i++)
 860                 mapping = ap->pages[i]->mapping;
 861
 862         if (mapping) {
 863                 struct inode *inode = mapping->host;
 864
 865                 /*
 866                  * Short read means EOF. If file size is larger, truncate it
 867                  */
 868                 if (!err && num_read < count)
 869                         fuse_short_read(inode, ia->read.attr_ver, num_read, ap);
 870
 871                 fuse_invalidate_atime(inode);
 872         }
 873
 874         for (i = 0; i < ap->num_pages; i++) {
 875                 struct page *page = ap->pages[i];
 876
 877                 if (!err)
 878                         SetPageUptodate(page);
 879                 else
 880                         SetPageError(page);
 881                 unlock_page(page);
 882                 put_page(page);
 883         }
 884         if (ia->ff)
 885                 fuse_file_put(ia->ff, false, false);
 886
 887         fuse_io_free(ia);
 888 }
 889
 890 static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file)
 891 {
 892         struct fuse_file *ff = file->private_data;
 893         struct fuse_conn *fc = ff->fc;
 894         struct fuse_args_pages *ap = &ia->ap;
 895         loff_t pos = page_offset(ap->pages[0]);
 896         size_t count = ap->num_pages << PAGE_SHIFT;
 897         ssize_t res;
 898         int err;
 899
 900         ap->args.out_pages = true;
 901         ap->args.page_zeroing = true;
 902         ap->args.page_replace = true;
 903
 904         /* Don't overflow end offset */
 905         if (pos + (count - 1) == LLONG_MAX) {
 906                 count--;
 907                 ap->descs[ap->num_pages - 1].length--;
 908         }
 909         WARN_ON((loff_t) (pos + count) < 0);
 910
 911         fuse_read_args_fill(ia, file, pos, count, FUSE_READ);
 912         ia->read.attr_ver = fuse_get_attr_version(fc);
 913         if (fc->async_read) {
 914                 ia->ff = fuse_file_get(ff);
 915                 ap->args.end = fuse_readpages_end;
 916                 err = fuse_simple_background(fc, &ap->args, GFP_KERNEL);
 917                 if (!err)
 918                         return;
 919         } else {
 920                 res = fuse_simple_request(fc, &ap->args);
 921                 err = res < 0 ? res : 0;
 922         }
 923         fuse_readpages_end(fc, &ap->args, err);
 924 }
 925
 926 struct fuse_fill_data {
 927         struct fuse_io_args *ia;
 928         struct file *file;
 929         struct inode *inode;
 930         unsigned int nr_pages;
 931         unsigned int max_pages;
 932 };
 933
 934 static int fuse_readpages_fill(void *_data, struct page *page)
 935 {
 936         struct fuse_fill_data *data = _data;
 937         struct fuse_io_args *ia = data->ia;
 938         struct fuse_args_pages *ap = &ia->ap;
 939         struct inode *inode = data->inode;
 940         struct fuse_conn *fc = get_fuse_conn(inode);
 941
 942         fuse_wait_on_page_writeback(inode, page->index);
 943
 944         if (ap->num_pages &&
 945             (ap->num_pages == fc->max_pages ||
 946              (ap->num_pages + 1) * PAGE_SIZE > fc->max_read ||
 947              ap->pages[ap->num_pages - 1]->index + 1 != page->index)) {
 948                 data->max_pages = min_t(unsigned int, data->nr_pages,
 949                                         fc->max_pages);
 950                 fuse_send_readpages(ia, data->file);
 951                 data->ia = ia = fuse_io_alloc(NULL, data->max_pages);
 952                 if (!ia) {
 953                         unlock_page(page);
 954                         return -ENOMEM;
 955                 }
 956                 ap = &ia->ap;
 957         }
 958
 959         if (WARN_ON(ap->num_pages >= data->max_pages)) {
 960                 unlock_page(page);
 961                 fuse_io_free(ia);
 962                 return -EIO;
 963         }
 964
 965         get_page(page);
 966         ap->pages[ap->num_pages] = page;
 967         ap->descs[ap->num_pages].length = PAGE_SIZE;
 968         ap->num_pages++;
 969         data->nr_pages--;
 970         return 0;
 971 }
 972
 973 static int fuse_readpages(struct file *file, struct address_space *mapping,
 974                           struct list_head *pages, unsigned nr_pages)
 975 {
 976         struct inode *inode = mapping->host;
 977         struct fuse_conn *fc = get_fuse_conn(inode);
 978         struct fuse_fill_data data;
 979         int err;
 980
 981         err = -EIO;
 982         if (fuse_is_bad(inode))
 983                 goto out;
 984
 985         data.file = file;
 986         data.inode = inode;
 987         data.nr_pages = nr_pages;
 988         data.max_pages = min_t(unsigned int, nr_pages, fc->max_pages);
 989 ;
 990         data.ia = fuse_io_alloc(NULL, data.max_pages);
 991         err = -ENOMEM;
 992         if (!data.ia)
 993                 goto out;
 994
 995         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 996         if (!err) {
 997                 if (data.ia->ap.num_pages)
 998                         fuse_send_readpages(data.ia, file);
 999                 else
1000                         fuse_io_free(data.ia);
1001         }
1002 out:
1003         return err;
1004 }
1005
1006 static ssize_t fuse_cache_read_iter(struct kiocb *iocb, struct iov_iter *to)
1007 {
1008         struct inode *inode = iocb->ki_filp->f_mapping->host;
1009         struct fuse_conn *fc = get_fuse_conn(inode);
1010
1011         /*
1012          * In auto invalidate mode, always update attributes on read.
1013          * Otherwise, only update if we attempt to read past EOF (to ensure
1014          * i_size is up to date).
1015          */
1016         if (fc->auto_inval_data ||
1017             (iocb->ki_pos + iov_iter_count(to) > i_size_read(inode))) {
1018                 int err;
1019                 err = fuse_update_attributes(inode, iocb->ki_filp);
1020                 if (err)
1021                         return err;
1022         }
1023
1024         return generic_file_read_iter(iocb, to);
1025 }
1026
1027 static void fuse_write_args_fill(struct fuse_io_args *ia, struct fuse_file *ff,
1028                                  loff_t pos, size_t count)
1029 {
1030         struct fuse_args *args = &ia->ap.args;
1031
1032         ia->write.in.fh = ff->fh;
1033         ia->write.in.offset = pos;
1034         ia->write.in.size = count;
1035         args->opcode = FUSE_WRITE;
1036         args->nodeid = ff->nodeid;
1037         args->in_numargs = 2;
1038         if (ff->fc->minor < 9)
1039                 args->in_args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
1040         else
1041                 args->in_args[0].size = sizeof(ia->write.in);
1042         args->in_args[0].value = &ia->write.in;
1043         args->in_args[1].size = count;
1044         args->out_numargs = 1;
1045         args->out_args[0].size = sizeof(ia->write.out);
1046         args->out_args[0].value = &ia->write.out;
1047 }
1048
1049 static unsigned int fuse_write_flags(struct kiocb *iocb)
1050 {
1051         unsigned int flags = iocb->ki_filp->f_flags;
1052
1053         if (iocb->ki_flags & IOCB_DSYNC)
1054                 flags |= O_DSYNC;
1055         if (iocb->ki_flags & IOCB_SYNC)
1056                 flags |= O_SYNC;
1057
1058         return flags;
1059 }
1060
1061 static ssize_t fuse_send_write(struct fuse_io_args *ia, loff_t pos,
1062                                size_t count, fl_owner_t owner)
1063 {
1064         struct kiocb *iocb = ia->io->iocb;
1065         struct file *file = iocb->ki_filp;
1066         struct fuse_file *ff = file->private_data;
1067         struct fuse_conn *fc = ff->fc;
1068         struct fuse_write_in *inarg = &ia->write.in;
1069         ssize_t err;
1070
1071         fuse_write_args_fill(ia, ff, pos, count);
1072         inarg->flags = fuse_write_flags(iocb);
1073         if (owner != NULL) {
1074                 inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
1075                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
1076         }
1077
1078         if (ia->io->async)
1079                 return fuse_async_req_send(fc, ia, count);
1080
1081         err = fuse_simple_request(fc, &ia->ap.args);
1082         if (!err && ia->write.out.size > count)
1083                 err = -EIO;
1084
1085         return err ?: ia->write.out.size;
1086 }
1087
1088 bool fuse_write_update_size(struct inode *inode, loff_t pos)
1089 {
1090         struct fuse_conn *fc = get_fuse_conn(inode);
1091         struct fuse_inode *fi = get_fuse_inode(inode);
1092         bool ret = false;
1093
1094         spin_lock(&fi->lock);
1095         fi->attr_version = atomic64_inc_return(&fc->attr_version);
1096         if (pos > inode->i_size) {
1097                 i_size_write(inode, pos);
1098                 ret = true;
1099         }
1100         spin_unlock(&fi->lock);
1101
1102         return ret;
1103 }
1104
1105 static ssize_t fuse_send_write_pages(struct fuse_io_args *ia,
1106                                      struct kiocb *iocb, struct inode *inode,
1107                                      loff_t pos, size_t count)
1108 {
1109         struct fuse_args_pages *ap = &ia->ap;
1110         struct file *file = iocb->ki_filp;
1111         struct fuse_file *ff = file->private_data;
1112         struct fuse_conn *fc = ff->fc;
1113         unsigned int offset, i;
1114         bool short_write;
1115         int err;
1116
1117         for (i = 0; i < ap->num_pages; i++)
1118                 fuse_wait_on_page_writeback(inode, ap->pages[i]->index);
1119
1120         fuse_write_args_fill(ia, ff, pos, count);
1121         ia->write.in.flags = fuse_write_flags(iocb);
1122
1123         err = fuse_simple_request(fc, &ap->args);
1124         if (!err && ia->write.out.size > count)
1125                 err = -EIO;
1126
1127         short_write = ia->write.out.size < count;
1128         offset = ap->descs[0].offset;
1129         count = ia->write.out.size;
1130         for (i = 0; i < ap->num_pages; i++) {
1131                 struct page *page = ap->pages[i];
1132
1133                 if (err) {
1134                         ClearPageUptodate(page);
1135                 } else {
1136                         if (count >= PAGE_SIZE - offset)
1137                                 count -= PAGE_SIZE - offset;
1138                         else {
1139                                 if (short_write)
1140                                         ClearPageUptodate(page);
1141                                 count = 0;
1142                         }
1143                         offset = 0;
1144                 }
1145                 if (ia->write.page_locked && (i == ap->num_pages - 1))
1146                         unlock_page(page);
1147                 put_page(page);
1148         }
1149
1150         return err;
1151 }
1152
1153 static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
1154                                      struct address_space *mapping,
1155                                      struct iov_iter *ii, loff_t pos,
1156                                      unsigned int max_pages)
1157 {
1158         struct fuse_args_pages *ap = &ia->ap;
1159         struct fuse_conn *fc = get_fuse_conn(mapping->host);
1160         unsigned offset = pos & (PAGE_SIZE - 1);
1161         size_t count = 0;
1162         int err;
1163
1164         ap->args.in_pages = true;
1165         ap->descs[0].offset = offset;
1166
1167         do {
1168                 size_t tmp;
1169                 struct page *page;
1170                 pgoff_t index = pos >> PAGE_SHIFT;
1171                 size_t bytes = min_t(size_t, PAGE_SIZE - offset,
1172                                      iov_iter_count(ii));
1173
1174                 bytes = min_t(size_t, bytes, fc->max_write - count);
1175
1176  again:
1177                 err = -EFAULT;
1178                 if (iov_iter_fault_in_readable(ii, bytes))
1179                         break;
1180
1181                 err = -ENOMEM;
1182                 page = grab_cache_page_write_begin(mapping, index, 0);
1183                 if (!page)
1184                         break;
1185
1186                 if (mapping_writably_mapped(mapping))
1187                         flush_dcache_page(page);
1188
1189                 tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
1190                 flush_dcache_page(page);
1191
1192                 iov_iter_advance(ii, tmp);
1193                 if (!tmp) {
1194                         unlock_page(page);
1195                         put_page(page);
1196                         bytes = min(bytes, iov_iter_single_seg_count(ii));
1197                         goto again;
1198                 }
1199
1200                 err = 0;
1201                 ap->pages[ap->num_pages] = page;
1202                 ap->descs[ap->num_pages].length = tmp;
1203                 ap->num_pages++;
1204
1205                 count += tmp;
1206                 pos += tmp;
1207                 offset += tmp;
1208                 if (offset == PAGE_SIZE)
1209                         offset = 0;
1210
1211                 /* If we copied full page, mark it uptodate */
1212                 if (tmp == PAGE_SIZE)
1213                         SetPageUptodate(page);
1214
1215                 if (PageUptodate(page)) {
1216                         unlock_page(page);
1217                 } else {
1218                         ia->write.page_locked = true;
1219                         break;
1220                 }
1221                 if (!fc->big_writes)
1222                         break;
1223         } while (iov_iter_count(ii) && count < fc->max_write &&
1224                  ap->num_pages < max_pages && offset == 0);
1225
1226         return count > 0 ? count : err;
1227 }
1228
1229 static inline unsigned int fuse_wr_pages(loff_t pos, size_t len,
1230                                      unsigned int max_pages)
1231 {
1232         return min_t(unsigned int,
1233                      ((pos + len - 1) >> PAGE_SHIFT) -
1234                      (pos >> PAGE_SHIFT) + 1,
1235                      max_pages);
1236 }
1237
1238 static ssize_t fuse_perform_write(struct kiocb *iocb,
1239                                   struct address_space *mapping,
1240                                   struct iov_iter *ii, loff_t pos)
1241 {
1242         struct inode *inode = mapping->host;
1243         struct fuse_conn *fc = get_fuse_conn(inode);
1244         struct fuse_inode *fi = get_fuse_inode(inode);
1245         int err = 0;
1246         ssize_t res = 0;
1247
1248         if (inode->i_size < pos + iov_iter_count(ii))
1249                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1250
1251         do {
1252                 ssize_t count;
1253                 struct fuse_io_args ia = {};
1254                 struct fuse_args_pages *ap = &ia.ap;
1255                 unsigned int nr_pages = fuse_wr_pages(pos, iov_iter_count(ii),
1256                                                       fc->max_pages);
1257
1258                 ap->pages = fuse_pages_alloc(nr_pages, GFP_KERNEL, &ap->descs);
1259                 if (!ap->pages) {
1260                         err = -ENOMEM;
1261                         break;
1262                 }
1263
1264                 count = fuse_fill_write_pages(&ia, mapping, ii, pos, nr_pages);
1265                 if (count <= 0) {
1266                         err = count;
1267                 } else {
1268                         err = fuse_send_write_pages(&ia, iocb, inode,
1269                                                     pos, count);
1270                         if (!err) {
1271                                 size_t num_written = ia.write.out.size;
1272
1273                                 res += num_written;
1274                                 pos += num_written;
1275
1276                                 /* break out of the loop on short write */
1277                                 if (num_written != count)
1278                                         err = -EIO;
1279                         }
1280                 }
1281                 kfree(ap->pages);
1282         } while (!err && iov_iter_count(ii));
1283
1284         if (res > 0)
1285                 fuse_write_update_size(inode, pos);
1286
1287         clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1288         fuse_invalidate_attr(inode);
1289
1290         return res > 0 ? res : err;
1291 }
1292
1293 static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
1294 {
1295         struct file *file = iocb->ki_filp;
1296         struct address_space *mapping = file->f_mapping;
1297         ssize_t written = 0;
1298         ssize_t written_buffered = 0;
1299         struct inode *inode = mapping->host;
1300         ssize_t err;
1301         loff_t endbyte = 0;
1302
1303         if (get_fuse_conn(inode)->writeback_cache) {
1304                 /* Update size (EOF optimization) and mode (SUID clearing) */
1305                 err = fuse_update_attributes(mapping->host, file);
1306                 if (err)
1307                         return err;
1308
1309                 return generic_file_write_iter(iocb, from);
1310         }
1311
1312         inode_lock(inode);
1313
1314         /* We can write back this queue in page reclaim */
1315         current->backing_dev_info = inode_to_bdi(inode);
1316
1317         err = generic_write_checks(iocb, from);
1318         if (err <= 0)
1319                 goto out;
1320
1321         err = file_remove_privs(file);
1322         if (err)
1323                 goto out;
1324
1325         err = file_update_time(file);
1326         if (err)
1327                 goto out;
1328
1329         if (iocb->ki_flags & IOCB_DIRECT) {
1330                 loff_t pos = iocb->ki_pos;
1331                 written = generic_file_direct_write(iocb, from);
1332                 if (written < 0 || !iov_iter_count(from))
1333                         goto out;
1334
1335                 pos += written;
1336
1337                 written_buffered = fuse_perform_write(iocb, mapping, from, pos);
1338                 if (written_buffered < 0) {
1339                         err = written_buffered;
1340                         goto out;
1341                 }
1342                 endbyte = pos + written_buffered - 1;
1343
1344                 err = filemap_write_and_wait_range(file->f_mapping, pos,
1345                                                    endbyte);
1346                 if (err)
1347                         goto out;
1348
1349                 invalidate_mapping_pages(file->f_mapping,
1350                                          pos >> PAGE_SHIFT,
1351                                          endbyte >> PAGE_SHIFT);
1352
1353                 written += written_buffered;
1354                 iocb->ki_pos = pos + written_buffered;
1355         } else {
1356                 written = fuse_perform_write(iocb, mapping, from, iocb->ki_pos);
1357                 if (written >= 0)
1358                         iocb->ki_pos += written;
1359         }
1360 out:
1361         current->backing_dev_info = NULL;
1362         inode_unlock(inode);
1363         if (written > 0)
1364                 written = generic_write_sync(iocb, written);
1365
1366         return written ? written : err;
1367 }
1368
1369 static inline void fuse_page_descs_length_init(struct fuse_page_desc *descs,
1370                                                unsigned int index,
1371                                                unsigned int nr_pages)
1372 {
1373         int i;
1374
1375         for (i = index; i < index + nr_pages; i++)
1376                 descs[i].length = PAGE_SIZE - descs[i].offset;
1377 }
1378
1379 static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii)
1380 {
1381         return (unsigned long)ii->iov->iov_base + ii->iov_offset;
1382 }
1383
1384 static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
1385                                         size_t max_size)
1386 {
1387         return min(iov_iter_single_seg_count(ii), max_size);
1388 }
1389
1390 static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,
1391                                size_t *nbytesp, int write,
1392                                unsigned int max_pages)
1393 {
1394         size_t nbytes = 0;  /* # bytes already packed in req */
1395         ssize_t ret = 0;
1396
1397         /* Special case for kernel I/O: can copy directly into the buffer */
1398         if (iov_iter_is_kvec(ii)) {
1399                 unsigned long user_addr = fuse_get_user_addr(ii);
1400                 size_t frag_size = fuse_get_frag_size(ii, *nbytesp);
1401
1402                 if (write)
1403                         ap->args.in_args[1].value = (void *) user_addr;
1404                 else
1405                         ap->args.out_args[0].value = (void *) user_addr;
1406
1407                 iov_iter_advance(ii, frag_size);
1408                 *nbytesp = frag_size;
1409                 return 0;
1410         }
1411
1412         while (nbytes < *nbytesp && ap->num_pages < max_pages) {
1413                 unsigned npages;
1414                 size_t start;
1415                 ret = iov_iter_get_pages(ii, &ap->pages[ap->num_pages],
1416                                         *nbytesp - nbytes,
1417                                         max_pages - ap->num_pages,
1418                                         &start);
1419                 if (ret < 0)
1420                         break;
1421
1422                 iov_iter_advance(ii, ret);
1423                 nbytes += ret;
1424
1425                 ret += start;
1426                 npages = (ret + PAGE_SIZE - 1) / PAGE_SIZE;
1427
1428                 ap->descs[ap->num_pages].offset = start;
1429                 fuse_page_descs_length_init(ap->descs, ap->num_pages, npages);
1430
1431                 ap->num_pages += npages;
1432                 ap->descs[ap->num_pages - 1].length -=
1433                         (PAGE_SIZE - ret) & (PAGE_SIZE - 1);
1434         }
1435
1436         ap->args.user_pages = true;
1437         if (write)
1438                 ap->args.in_pages = 1;
1439         else
1440                 ap->args.out_pages = 1;
1441
1442         *nbytesp = nbytes;
1443
1444         return ret < 0 ? ret : 0;
1445 }
1446
1447 ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
1448                        loff_t *ppos, int flags)
1449 {
1450         int write = flags & FUSE_DIO_WRITE;
1451         int cuse = flags & FUSE_DIO_CUSE;
1452         struct file *file = io->iocb->ki_filp;
1453         struct inode *inode = file->f_mapping->host;
1454         struct fuse_file *ff = file->private_data;
1455         struct fuse_conn *fc = ff->fc;
1456         size_t nmax = write ? fc->max_write : fc->max_read;
1457         loff_t pos = *ppos;
1458         size_t count = iov_iter_count(iter);
1459         pgoff_t idx_from = pos >> PAGE_SHIFT;
1460         pgoff_t idx_to = (pos + count - 1) >> PAGE_SHIFT;
1461         ssize_t res = 0;
1462         int err = 0;
1463         struct fuse_io_args *ia;
1464         unsigned int max_pages;
1465
1466         max_pages = iov_iter_npages(iter, fc->max_pages);
1467         ia = fuse_io_alloc(io, max_pages);
1468         if (!ia)
1469                 return -ENOMEM;
1470
1471         ia->io = io;
1472         if (!cuse && fuse_range_is_writeback(inode, idx_from, idx_to)) {
1473                 if (!write)
1474                         inode_lock(inode);
1475                 fuse_sync_writes(inode);
1476                 if (!write)
1477                         inode_unlock(inode);
1478         }
1479
1480         io->should_dirty = !write && iter_is_iovec(iter);
1481         while (count) {
1482                 ssize_t nres;
1483                 fl_owner_t owner = current->files;
1484                 size_t nbytes = min(count, nmax);
1485
1486                 err = fuse_get_user_pages(&ia->ap, iter, &nbytes, write,
1487                                           max_pages);
1488                 if (err && !nbytes)
1489                         break;
1490
1491                 if (write) {
1492                         if (!capable(CAP_FSETID))
1493                                 ia->write.in.write_flags |= FUSE_WRITE_KILL_PRIV;
1494
1495                         nres = fuse_send_write(ia, pos, nbytes, owner);
1496                 } else {
1497                         nres = fuse_send_read(ia, pos, nbytes, owner);
1498                 }
1499
1500                 if (!io->async || nres < 0) {
1501                         fuse_release_user_pages(&ia->ap, io->should_dirty);
1502                         fuse_io_free(ia);
1503                 }
1504                 ia = NULL;
1505                 if (nres < 0) {
1506                         iov_iter_revert(iter, nbytes);
1507                         err = nres;
1508                         break;
1509                 }
1510                 WARN_ON(nres > nbytes);
1511
1512                 count -= nres;
1513                 res += nres;
1514                 pos += nres;
1515                 if (nres != nbytes) {
1516                         iov_iter_revert(iter, nbytes - nres);
1517                         break;
1518                 }
1519                 if (count) {
1520                         max_pages = iov_iter_npages(iter, fc->max_pages);
1521                         ia = fuse_io_alloc(io, max_pages);
1522                         if (!ia)
1523                                 break;
1524                 }
1525         }
1526         if (ia)
1527                 fuse_io_free(ia);
1528         if (res > 0)
1529                 *ppos = pos;
1530
1531         return res > 0 ? res : err;
1532 }
1533 EXPORT_SYMBOL_GPL(fuse_direct_io);
1534
1535 static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
1536                                   struct iov_iter *iter,
1537                                   loff_t *ppos)
1538 {
1539         ssize_t res;
1540         struct inode *inode = file_inode(io->iocb->ki_filp);
1541
1542         res = fuse_direct_io(io, iter, ppos, 0);
1543
1544         fuse_invalidate_atime(inode);
1545
1546         return res;
1547 }
1548
1549 static ssize_t fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
1550
1551 static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to)
1552 {
1553         ssize_t res;
1554
1555         if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
1556                 res = fuse_direct_IO(iocb, to);
1557         } else {
1558                 struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
1559
1560                 res = __fuse_direct_read(&io, to, &iocb->ki_pos);
1561         }
1562
1563         return res;
1564 }
1565
1566 static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
1567 {
1568         struct inode *inode = file_inode(iocb->ki_filp);
1569         struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
1570         ssize_t res;
1571
1572         /* Don't allow parallel writes to the same file */
1573         inode_lock(inode);
1574         res = generic_write_checks(iocb, from);
1575         if (res > 0) {
1576                 if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
1577                         res = fuse_direct_IO(iocb, from);
1578                 } else {
1579                         res = fuse_direct_io(&io, from, &iocb->ki_pos,
1580                                              FUSE_DIO_WRITE);
1581                 }
1582         }
1583         fuse_invalidate_attr(inode);
1584         if (res > 0)
1585                 fuse_write_update_size(inode, iocb->ki_pos);
1586         inode_unlock(inode);
1587
1588         return res;
1589 }
1590
1591 static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
1592 {
1593         struct file *file = iocb->ki_filp;
1594         struct fuse_file *ff = file->private_data;
1595
1596         if (fuse_is_bad(file_inode(file)))
1597                 return -EIO;
1598
1599         if (!(ff->open_flags & FOPEN_DIRECT_IO))
1600                 return fuse_cache_read_iter(iocb, to);
1601         else
1602                 return fuse_direct_read_iter(iocb, to);
1603 }
1604
1605 static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
1606 {
1607         struct file *file = iocb->ki_filp;
1608         struct fuse_file *ff = file->private_data;
1609
1610         if (fuse_is_bad(file_inode(file)))
1611                 return -EIO;
1612
1613         if (!(ff->open_flags & FOPEN_DIRECT_IO))
1614                 return fuse_cache_write_iter(iocb, from);
1615         else
1616                 return fuse_direct_write_iter(iocb, from);
1617 }
1618
1619 static void fuse_writepage_free(struct fuse_writepage_args *wpa)
1620 {
1621         struct fuse_args_pages *ap = &wpa->ia.ap;
1622         int i;
1623
1624         for (i = 0; i < ap->num_pages; i++)
1625                 __free_page(ap->pages[i]);
1626
1627         if (wpa->ia.ff)
1628                 fuse_file_put(wpa->ia.ff, false, false);
1629
1630         kfree(ap->pages);
1631         kfree(wpa);
1632 }
1633
1634 static void fuse_writepage_finish(struct fuse_conn *fc,
1635                                   struct fuse_writepage_args *wpa)
1636 {
1637         struct fuse_args_pages *ap = &wpa->ia.ap;
1638         struct inode *inode = wpa->inode;
1639         struct fuse_inode *fi = get_fuse_inode(inode);
1640         struct backing_dev_info *bdi = inode_to_bdi(inode);
1641         int i;
1642
1643         list_del(&wpa->writepages_entry);
1644         for (i = 0; i < ap->num_pages; i++) {
1645                 dec_wb_stat(&bdi->wb, WB_WRITEBACK);
1646                 dec_node_page_state(ap->pages[i], NR_WRITEBACK_TEMP);
1647                 wb_writeout_inc(&bdi->wb);
1648         }
1649         wake_up(&fi->page_waitq);
1650 }
1651
1652 /* Called under fi->lock, may release and reacquire it */
1653 static void fuse_send_writepage(struct fuse_conn *fc,
1654                                 struct fuse_writepage_args *wpa, loff_t size)
1655 __releases(fi->lock)
1656 __acquires(fi->lock)
1657 {
1658         struct fuse_writepage_args *aux, *next;
1659         struct fuse_inode *fi = get_fuse_inode(wpa->inode);
1660         struct fuse_write_in *inarg = &wpa->ia.write.in;
1661         struct fuse_args *args = &wpa->ia.ap.args;
1662         __u64 data_size = wpa->ia.ap.num_pages * PAGE_SIZE;
1663         int err;
1664
1665         fi->writectr++;
1666         if (inarg->offset + data_size <= size) {
1667                 inarg->size = data_size;
1668         } else if (inarg->offset < size) {
1669                 inarg->size = size - inarg->offset;
1670         } else {
1671                 /* Got truncated off completely */
1672                 goto out_free;
1673         }
1674
1675         args->in_args[1].size = inarg->size;
1676         args->force = true;
1677         args->nocreds = true;
1678
1679         err = fuse_simple_background(fc, args, GFP_ATOMIC);
1680         if (err == -ENOMEM) {
1681                 spin_unlock(&fi->lock);
1682                 err = fuse_simple_background(fc, args, GFP_NOFS | __GFP_NOFAIL);
1683                 spin_lock(&fi->lock);
1684         }
1685
1686         /* Fails on broken connection only */
1687         if (unlikely(err))
1688                 goto out_free;
1689
1690         return;
1691
1692  out_free:
1693         fi->writectr--;
1694         fuse_writepage_finish(fc, wpa);
1695         spin_unlock(&fi->lock);
1696
1697         /* After fuse_writepage_finish() aux request list is private */
1698         for (aux = wpa->next; aux; aux = next) {
1699                 next = aux->next;
1700                 aux->next = NULL;
1701                 fuse_writepage_free(aux);
1702         }
1703
1704         fuse_writepage_free(wpa);
1705         spin_lock(&fi->lock);
1706 }
1707
1708 /*
1709  * If fi->writectr is positive (no truncate or fsync going on) send
1710  * all queued writepage requests.
1711  *
1712  * Called with fi->lock
1713  */
1714 void fuse_flush_writepages(struct inode *inode)
1715 __releases(fi->lock)
1716 __acquires(fi->lock)
1717 {
1718         struct fuse_conn *fc = get_fuse_conn(inode);
1719         struct fuse_inode *fi = get_fuse_inode(inode);
1720         loff_t crop = i_size_read(inode);
1721         struct fuse_writepage_args *wpa;
1722
1723         while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
1724                 wpa = list_entry(fi->queued_writes.next,
1725                                  struct fuse_writepage_args, queue_entry);
1726                 list_del_init(&wpa->queue_entry);
1727                 fuse_send_writepage(fc, wpa, crop);
1728         }
1729 }
1730
1731 static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_args *args,
1732                                int error)
1733 {
1734         struct fuse_writepage_args *wpa =
1735                 container_of(args, typeof(*wpa), ia.ap.args);
1736         struct inode *inode = wpa->inode;
1737         struct fuse_inode *fi = get_fuse_inode(inode);
1738
1739         mapping_set_error(inode->i_mapping, error);
1740         spin_lock(&fi->lock);
1741         while (wpa->next) {
1742                 struct fuse_conn *fc = get_fuse_conn(inode);
1743                 struct fuse_write_in *inarg = &wpa->ia.write.in;
1744                 struct fuse_writepage_args *next = wpa->next;
1745
1746                 wpa->next = next->next;
1747                 next->next = NULL;
1748                 next->ia.ff = fuse_file_get(wpa->ia.ff);
1749                 list_add(&next->writepages_entry, &fi->writepages);
1750
1751                 /*
1752                  * Skip fuse_flush_writepages() to make it easy to crop requests
1753                  * based on primary request size.
1754                  *
1755                  * 1st case (trivial): there are no concurrent activities using
1756                  * fuse_set/release_nowrite.  Then we're on safe side because
1757                  * fuse_flush_writepages() would call fuse_send_writepage()
1758                  * anyway.
1759                  *
1760                  * 2nd case: someone called fuse_set_nowrite and it is waiting
1761                  * now for completion of all in-flight requests.  This happens
1762                  * rarely and no more than once per page, so this should be
1763                  * okay.
1764                  *
1765                  * 3rd case: someone (e.g. fuse_do_setattr()) is in the middle
1766                  * of fuse_set_nowrite..fuse_release_nowrite section.  The fact
1767                  * that fuse_set_nowrite returned implies that all in-flight
1768                  * requests were completed along with all of their secondary
1769                  * requests.  Further primary requests are blocked by negative
1770                  * writectr.  Hence there cannot be any in-flight requests and
1771                  * no invocations of fuse_writepage_end() while we're in
1772                  * fuse_set_nowrite..fuse_release_nowrite section.
1773                  */
1774                 fuse_send_writepage(fc, next, inarg->offset + inarg->size);
1775         }
1776         fi->writectr--;
1777         fuse_writepage_finish(fc, wpa);
1778         spin_unlock(&fi->lock);
1779         fuse_writepage_free(wpa);
1780 }
1781
1782 static struct fuse_file *__fuse_write_file_get(struct fuse_conn *fc,
1783                                                struct fuse_inode *fi)
1784 {
1785         struct fuse_file *ff = NULL;
1786
1787         spin_lock(&fi->lock);
1788         if (!list_empty(&fi->write_files)) {
1789                 ff = list_entry(fi->write_files.next, struct fuse_file,
1790                                 write_entry);
1791                 fuse_file_get(ff);
1792         }
1793         spin_unlock(&fi->lock);
1794
1795         return ff;
1796 }
1797
1798 static struct fuse_file *fuse_write_file_get(struct fuse_conn *fc,
1799                                              struct fuse_inode *fi)
1800 {
1801         struct fuse_file *ff = __fuse_write_file_get(fc, fi);
1802         WARN_ON(!ff);
1803         return ff;
1804 }
1805
1806 int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
1807 {
1808         struct fuse_conn *fc = get_fuse_conn(inode);
1809         struct fuse_inode *fi = get_fuse_inode(inode);
1810         struct fuse_file *ff;
1811         int err;
1812
1813         ff = __fuse_write_file_get(fc, fi);
1814         err = fuse_flush_times(inode, ff);
1815         if (ff)
1816                 fuse_file_put(ff, false, false);
1817
1818         return err;
1819 }
1820
1821 static struct fuse_writepage_args *fuse_writepage_args_alloc(void)
1822 {
1823         struct fuse_writepage_args *wpa;
1824         struct fuse_args_pages *ap;
1825
1826         wpa = kzalloc(sizeof(*wpa), GFP_NOFS);
1827         if (wpa) {
1828                 ap = &wpa->ia.ap;
1829                 ap->num_pages = 0;
1830                 ap->pages = fuse_pages_alloc(1, GFP_NOFS, &ap->descs);
1831                 if (!ap->pages) {
1832                         kfree(wpa);
1833                         wpa = NULL;
1834                 }
1835         }
1836         return wpa;
1837
1838 }
1839
1840 static int fuse_writepage_locked(struct page *page)
1841 {
1842         struct address_space *mapping = page->mapping;
1843         struct inode *inode = mapping->host;
1844         struct fuse_conn *fc = get_fuse_conn(inode);
1845         struct fuse_inode *fi = get_fuse_inode(inode);
1846         struct fuse_writepage_args *wpa;
1847         struct fuse_args_pages *ap;
1848         struct page *tmp_page;
1849         int error = -ENOMEM;
1850
1851         set_page_writeback(page);
1852
1853         wpa = fuse_writepage_args_alloc();
1854         if (!wpa)
1855                 goto err;
1856         ap = &wpa->ia.ap;
1857
1858         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1859         if (!tmp_page)
1860                 goto err_free;
1861
1862         error = -EIO;
1863         wpa->ia.ff = fuse_write_file_get(fc, fi);
1864         if (!wpa->ia.ff)
1865                 goto err_nofile;
1866
1867         fuse_write_args_fill(&wpa->ia, wpa->ia.ff, page_offset(page), 0);
1868
1869         copy_highpage(tmp_page, page);
1870         wpa->ia.write.in.write_flags |= FUSE_WRITE_CACHE;
1871         wpa->next = NULL;
1872         ap->args.in_pages = true;
1873         ap->num_pages = 1;
1874         ap->pages[0] = tmp_page;
1875         ap->descs[0].offset = 0;
1876         ap->descs[0].length = PAGE_SIZE;
1877         ap->args.end = fuse_writepage_end;
1878         wpa->inode = inode;
1879
1880         inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
1881         inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);
1882
1883         spin_lock(&fi->lock);
1884         list_add(&wpa->writepages_entry, &fi->writepages);
1885         list_add_tail(&wpa->queue_entry, &fi->queued_writes);
1886         fuse_flush_writepages(inode);
1887         spin_unlock(&fi->lock);
1888
1889         end_page_writeback(page);
1890
1891         return 0;
1892
1893 err_nofile:
1894         __free_page(tmp_page);
1895 err_free:
1896         kfree(wpa);
1897 err:
1898         mapping_set_error(page->mapping, error);
1899         end_page_writeback(page);
1900         return error;
1901 }
1902
1903 static int fuse_writepage(struct page *page, struct writeback_control *wbc)
1904 {
1905         int err;
1906
1907         if (fuse_page_is_writeback(page->mapping->host, page->index)) {
1908                 /*
1909                  * ->writepages() should be called for sync() and friends.  We
1910                  * should only get here on direct reclaim and then we are
1911                  * allowed to skip a page which is already in flight
1912                  */
1913                 WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
1914
1915                 redirty_page_for_writepage(wbc, page);
1916                 unlock_page(page);
1917                 return 0;
1918         }
1919
1920         err = fuse_writepage_locked(page);
1921         unlock_page(page);
1922
1923         return err;
1924 }
1925
1926 struct fuse_fill_wb_data {
1927         struct fuse_writepage_args *wpa;
1928         struct fuse_file *ff;
1929         struct inode *inode;
1930         struct page **orig_pages;
1931         unsigned int max_pages;
1932 };
1933
1934 static bool fuse_pages_realloc(struct fuse_fill_wb_data *data)
1935 {
1936         struct fuse_args_pages *ap = &data->wpa->ia.ap;
1937         struct fuse_conn *fc = get_fuse_conn(data->inode);
1938         struct page **pages;
1939         struct fuse_page_desc *descs;
1940         unsigned int npages = min_t(unsigned int,
1941                                     max_t(unsigned int, data->max_pages * 2,
1942                                           FUSE_DEFAULT_MAX_PAGES_PER_REQ),
1943                                     fc->max_pages);
1944         WARN_ON(npages <= data->max_pages);
1945
1946         pages = fuse_pages_alloc(npages, GFP_NOFS, &descs);
1947         if (!pages)
1948                 return false;
1949
1950         memcpy(pages, ap->pages, sizeof(struct page *) * ap->num_pages);
1951         memcpy(descs, ap->descs, sizeof(struct fuse_page_desc) * ap->num_pages);
1952         kfree(ap->pages);
1953         ap->pages = pages;
1954         ap->descs = descs;
1955         data->max_pages = npages;
1956
1957         return true;
1958 }
1959
1960 static void fuse_writepages_send(struct fuse_fill_wb_data *data)
1961 {
1962         struct fuse_writepage_args *wpa = data->wpa;
1963         struct inode *inode = data->inode;
1964         struct fuse_inode *fi = get_fuse_inode(inode);
1965         int num_pages = wpa->ia.ap.num_pages;
1966         int i;
1967
1968         wpa->ia.ff = fuse_file_get(data->ff);
1969         spin_lock(&fi->lock);
1970         list_add_tail(&wpa->queue_entry, &fi->queued_writes);
1971         fuse_flush_writepages(inode);
1972         spin_unlock(&fi->lock);
1973
1974         for (i = 0; i < num_pages; i++)
1975                 end_page_writeback(data->orig_pages[i]);
1976 }
1977
1978 /*
1979  * First recheck under fi->lock if the offending offset is still under
1980  * writeback.  If yes, then iterate auxiliary write requests, to see if there's
1981  * one already added for a page at this offset.  If there's none, then insert
1982  * this new request onto the auxiliary list, otherwise reuse the existing one by
1983  * copying the new page contents over to the old temporary page.
1984  */
1985 static bool fuse_writepage_in_flight(struct fuse_writepage_args *new_wpa,
1986                                      struct page *page)
1987 {
1988         struct fuse_inode *fi = get_fuse_inode(new_wpa->inode);
1989         struct fuse_writepage_args *tmp;
1990         struct fuse_writepage_args *old_wpa;
1991         struct fuse_args_pages *new_ap = &new_wpa->ia.ap;
1992
1993         WARN_ON(new_ap->num_pages != 0);
1994
1995         spin_lock(&fi->lock);
1996         list_del(&new_wpa->writepages_entry);
1997         old_wpa = fuse_find_writeback(fi, page->index, page->index);
1998         if (!old_wpa) {
1999                 list_add(&new_wpa->writepages_entry, &fi->writepages);
2000                 spin_unlock(&fi->lock);
2001                 return false;
2002         }
2003
2004         new_ap->num_pages = 1;
2005         for (tmp = old_wpa->next; tmp; tmp = tmp->next) {
2006                 pgoff_t curr_index;
2007
2008                 WARN_ON(tmp->inode != new_wpa->inode);
2009                 curr_index = tmp->ia.write.in.offset >> PAGE_SHIFT;
2010                 if (curr_index == page->index) {
2011                         WARN_ON(tmp->ia.ap.num_pages != 1);
2012                         swap(tmp->ia.ap.pages[0], new_ap->pages[0]);
2013                         break;
2014                 }
2015         }
2016
2017         if (!tmp) {
2018                 new_wpa->next = old_wpa->next;
2019                 old_wpa->next = new_wpa;
2020         }
2021
2022         spin_unlock(&fi->lock);
2023
2024         if (tmp) {
2025                 struct backing_dev_info *bdi = inode_to_bdi(new_wpa->inode);
2026
2027                 dec_wb_stat(&bdi->wb, WB_WRITEBACK);
2028                 dec_node_page_state(new_ap->pages[0], NR_WRITEBACK_TEMP);
2029                 wb_writeout_inc(&bdi->wb);
2030                 fuse_writepage_free(new_wpa);
2031         }
2032
2033         return true;
2034 }
2035
2036 static int fuse_writepages_fill(struct page *page,
2037                 struct writeback_control *wbc, void *_data)
2038 {
2039         struct fuse_fill_wb_data *data = _data;
2040         struct fuse_writepage_args *wpa = data->wpa;
2041         struct fuse_args_pages *ap = &wpa->ia.ap;
2042         struct inode *inode = data->inode;
2043         struct fuse_inode *fi = get_fuse_inode(inode);
2044         struct fuse_conn *fc = get_fuse_conn(inode);
2045         struct page *tmp_page;
2046         bool is_writeback;
2047         int err;
2048
2049         if (!data->ff) {
2050                 err = -EIO;
2051                 data->ff = fuse_write_file_get(fc, fi);
2052                 if (!data->ff)
2053                         goto out_unlock;
2054         }
2055
2056         /*
2057          * Being under writeback is unlikely but possible.  For example direct
2058          * read to an mmaped fuse file will set the page dirty twice; once when
2059          * the pages are faulted with get_user_pages(), and then after the read
2060          * completed.
2061          */
2062         is_writeback = fuse_page_is_writeback(inode, page->index);
2063
2064         if (wpa && ap->num_pages &&
2065             (is_writeback || ap->num_pages == fc->max_pages ||
2066              (ap->num_pages + 1) * PAGE_SIZE > fc->max_write ||
2067              data->orig_pages[ap->num_pages - 1]->index + 1 != page->index)) {
2068                 fuse_writepages_send(data);
2069                 data->wpa = NULL;
2070         } else if (wpa && ap->num_pages == data->max_pages) {
2071                 if (!fuse_pages_realloc(data)) {
2072                         fuse_writepages_send(data);
2073                         data->wpa = NULL;
2074                 }
2075         }
2076
2077         err = -ENOMEM;
2078         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
2079         if (!tmp_page)
2080                 goto out_unlock;
2081
2082         /*
2083          * The page must not be redirtied until the writeout is completed
2084          * (i.e. userspace has sent a reply to the write request).  Otherwise
2085          * there could be more than one temporary page instance for each real
2086          * page.
2087          *
2088          * This is ensured by holding the page lock in page_mkwrite() while
2089          * checking fuse_page_is_writeback().  We already hold the page lock
2090          * since clear_page_dirty_for_io() and keep it held until we add the
2091          * request to the fi->writepages list and increment ap->num_pages.
2092          * After this fuse_page_is_writeback() will indicate that the page is
2093          * under writeback, so we can release the page lock.
2094          */
2095         if (data->wpa == NULL) {
2096                 err = -ENOMEM;
2097                 wpa = fuse_writepage_args_alloc();
2098                 if (!wpa) {
2099                         __free_page(tmp_page);
2100                         goto out_unlock;
2101                 }
2102                 data->max_pages = 1;
2103
2104                 ap = &wpa->ia.ap;
2105                 fuse_write_args_fill(&wpa->ia, data->ff, page_offset(page), 0);
2106                 wpa->ia.write.in.write_flags |= FUSE_WRITE_CACHE;
2107                 wpa->next = NULL;
2108                 ap->args.in_pages = true;
2109                 ap->args.end = fuse_writepage_end;
2110                 ap->num_pages = 0;
2111                 wpa->inode = inode;
2112
2113                 spin_lock(&fi->lock);
2114                 list_add(&wpa->writepages_entry, &fi->writepages);
2115                 spin_unlock(&fi->lock);
2116
2117                 data->wpa = wpa;
2118         }
2119         set_page_writeback(page);
2120
2121         copy_highpage(tmp_page, page);
2122         ap->pages[ap->num_pages] = tmp_page;
2123         ap->descs[ap->num_pages].offset = 0;
2124         ap->descs[ap->num_pages].length = PAGE_SIZE;
2125
2126         inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
2127         inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);
2128
2129         err = 0;
2130         if (is_writeback && fuse_writepage_in_flight(wpa, page)) {
2131                 end_page_writeback(page);
2132                 data->wpa = NULL;
2133                 goto out_unlock;
2134         }
2135         data->orig_pages[ap->num_pages] = page;
2136
2137         /*
2138          * Protected by fi->lock against concurrent access by
2139          * fuse_page_is_writeback().
2140          */
2141         spin_lock(&fi->lock);
2142         ap->num_pages++;
2143         spin_unlock(&fi->lock);
2144
2145 out_unlock:
2146         unlock_page(page);
2147
2148         return err;
2149 }
2150
2151 static int fuse_writepages(struct address_space *mapping,
2152                            struct writeback_control *wbc)
2153 {
2154         struct inode *inode = mapping->host;
2155         struct fuse_conn *fc = get_fuse_conn(inode);
2156         struct fuse_fill_wb_data data;
2157         int err;
2158
2159         err = -EIO;
2160         if (fuse_is_bad(inode))
2161                 goto out;
2162
2163         data.inode = inode;
2164         data.wpa = NULL;
2165         data.ff = NULL;
2166
2167         err = -ENOMEM;
2168         data.orig_pages = kcalloc(fc->max_pages,
2169                                   sizeof(struct page *),
2170                                   GFP_NOFS);
2171         if (!data.orig_pages)
2172                 goto out;
2173
2174         err = write_cache_pages(mapping, wbc, fuse_writepages_fill, &data);
2175         if (data.wpa) {
2176                 WARN_ON(!data.wpa->ia.ap.num_pages);
2177                 fuse_writepages_send(&data);
2178         }
2179         if (data.ff)
2180                 fuse_file_put(data.ff, false, false);
2181
2182         kfree(data.orig_pages);
2183 out:
2184         return err;
2185 }
2186
2187 /*
2188  * It's worthy to make sure that space is reserved on disk for the write,
2189  * but how to implement it without killing performance need more thinking.
2190  */
2191 static int fuse_write_begin(struct file *file, struct address_space *mapping,
2192                 loff_t pos, unsigned len, unsigned flags,
2193                 struct page **pagep, void **fsdata)
2194 {
2195         pgoff_t index = pos >> PAGE_SHIFT;
2196         struct fuse_conn *fc = get_fuse_conn(file_inode(file));
2197         struct page *page;
2198         loff_t fsize;
2199         int err = -ENOMEM;
2200
2201         WARN_ON(!fc->writeback_cache);
2202
2203         page = grab_cache_page_write_begin(mapping, index, flags);
2204         if (!page)
2205                 goto error;
2206
2207         fuse_wait_on_page_writeback(mapping->host, page->index);
2208
2209         if (PageUptodate(page) || len == PAGE_SIZE)
2210                 goto success;
2211         /*
2212          * Check if the start this page comes after the end of file, in which
2213          * case the readpage can be optimized away.
2214          */
2215         fsize = i_size_read(mapping->host);
2216         if (fsize <= (pos & PAGE_MASK)) {
2217                 size_t off = pos & ~PAGE_MASK;
2218                 if (off)
2219                         zero_user_segment(page, 0, off);
2220                 goto success;
2221         }
2222         err = fuse_do_readpage(file, page);
2223         if (err)
2224                 goto cleanup;
2225 success:
2226         *pagep = page;
2227         return 0;
2228
2229 cleanup:
2230         unlock_page(page);
2231         put_page(page);
2232 error:
2233         return err;
2234 }
2235
2236 static int fuse_write_end(struct file *file, struct address_space *mapping,
2237                 loff_t pos, unsigned len, unsigned copied,
2238                 struct page *page, void *fsdata)
2239 {
2240         struct inode *inode = page->mapping->host;
2241
2242         /* Haven't copied anything?  Skip zeroing, size extending, dirtying. */
2243         if (!copied)
2244                 goto unlock;
2245
2246         if (!PageUptodate(page)) {
2247                 /* Zero any unwritten bytes at the end of the page */
2248                 size_t endoff = (pos + copied) & ~PAGE_MASK;
2249                 if (endoff)
2250                         zero_user_segment(page, endoff, PAGE_SIZE);
2251                 SetPageUptodate(page);
2252         }
2253
2254         fuse_write_update_size(inode, pos + copied);
2255         set_page_dirty(page);
2256
2257 unlock:
2258         unlock_page(page);
2259         put_page(page);
2260
2261         return copied;
2262 }
2263
2264 static int fuse_launder_page(struct page *page)
2265 {
2266         int err = 0;
2267         if (clear_page_dirty_for_io(page)) {
2268                 struct inode *inode = page->mapping->host;
2269                 err = fuse_writepage_locked(page);
2270                 if (!err)
2271                         fuse_wait_on_page_writeback(inode, page->index);
2272         }
2273         return err;
2274 }
2275
2276 /*
2277  * Write back dirty pages now, because there may not be any suitable
2278  * open files later
2279  */
2280 static void fuse_vma_close(struct vm_area_struct *vma)
2281 {
2282         filemap_write_and_wait(vma->vm_file->f_mapping);
2283 }
2284
2285 /*
2286  * Wait for writeback against this page to complete before allowing it
2287  * to be marked dirty again, and hence written back again, possibly
2288  * before the previous writepage completed.
2289  *
2290  * Block here, instead of in ->writepage(), so that the userspace fs
2291  * can only block processes actually operating on the filesystem.
2292  *
2293  * Otherwise unprivileged userspace fs would be able to block
2294  * unrelated:
2295  *
2296  * - page migration
2297  * - sync(2)
2298  * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
2299  */
2300 static vm_fault_t fuse_page_mkwrite(struct vm_fault *vmf)
2301 {
2302         struct page *page = vmf->page;
2303         struct inode *inode = file_inode(vmf->vma->vm_file);
2304
2305         file_update_time(vmf->vma->vm_file);
2306         lock_page(page);
2307         if (page->mapping != inode->i_mapping) {
2308                 unlock_page(page);
2309                 return VM_FAULT_NOPAGE;
2310         }
2311
2312         fuse_wait_on_page_writeback(inode, page->index);
2313         return VM_FAULT_LOCKED;
2314 }
2315
2316 static const struct vm_operations_struct fuse_file_vm_ops = {
2317         .close          = fuse_vma_close,
2318         .fault          = filemap_fault,
2319         .map_pages      = filemap_map_pages,
2320         .page_mkwrite   = fuse_page_mkwrite,
2321 };
2322
2323 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
2324 {
2325         struct fuse_file *ff = file->private_data;
2326
2327         if (ff->open_flags & FOPEN_DIRECT_IO) {
2328                 /* Can't provide the coherency needed for MAP_SHARED */
2329                 if (vma->vm_flags & VM_MAYSHARE)
2330                         return -ENODEV;
2331
2332                 invalidate_inode_pages2(file->f_mapping);
2333
2334                 return generic_file_mmap(file, vma);
2335         }
2336
2337         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2338                 fuse_link_write_file(file);
2339
2340         file_accessed(file);
2341         vma->vm_ops = &fuse_file_vm_ops;
2342         return 0;
2343 }
2344
2345 static int convert_fuse_file_lock(struct fuse_conn *fc,
2346                                   const struct fuse_file_lock *ffl,
2347                                   struct file_lock *fl)
2348 {
2349         switch (ffl->type) {
2350         case F_UNLCK:
2351                 break;
2352
2353         case F_RDLCK:
2354         case F_WRLCK:
2355                 if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
2356                     ffl->end < ffl->start)
2357                         return -EIO;
2358
2359                 fl->fl_start = ffl->start;
2360                 fl->fl_end = ffl->end;
2361
2362                 /*
2363                  * Convert pid into init's pid namespace.  The locks API will
2364                  * translate it into the caller's pid namespace.
2365                  */
2366                 rcu_read_lock();
2367                 fl->fl_pid = pid_nr_ns(find_pid_ns(ffl->pid, fc->pid_ns), &init_pid_ns);
2368                 rcu_read_unlock();
2369                 break;
2370
2371         default:
2372                 return -EIO;
2373         }
2374         fl->fl_type = ffl->type;
2375         return 0;
2376 }
2377
2378 static void fuse_lk_fill(struct fuse_args *args, struct file *file,
2379                          const struct file_lock *fl, int opcode, pid_t pid,
2380                          int flock, struct fuse_lk_in *inarg)
2381 {
2382         struct inode *inode = file_inode(file);
2383         struct fuse_conn *fc = get_fuse_conn(inode);
2384         struct fuse_file *ff = file->private_data;
2385
2386         memset(inarg, 0, sizeof(*inarg));
2387         inarg->fh = ff->fh;
2388         inarg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
2389         inarg->lk.start = fl->fl_start;
2390         inarg->lk.end = fl->fl_end;
2391         inarg->lk.type = fl->fl_type;
2392         inarg->lk.pid = pid;
2393         if (flock)
2394                 inarg->lk_flags |= FUSE_LK_FLOCK;
2395         args->opcode = opcode;
2396         args->nodeid = get_node_id(inode);
2397         args->in_numargs = 1;
2398         args->in_args[0].size = sizeof(*inarg);
2399         args->in_args[0].value = inarg;
2400 }
2401
2402 static int fuse_getlk(struct file *file, struct file_lock *fl)
2403 {
2404         struct inode *inode = file_inode(file);
2405         struct fuse_conn *fc = get_fuse_conn(inode);
2406         FUSE_ARGS(args);
2407         struct fuse_lk_in inarg;
2408         struct fuse_lk_out outarg;
2409         int err;
2410
2411         fuse_lk_fill(&args, file, fl, FUSE_GETLK, 0, 0, &inarg);
2412         args.out_numargs = 1;
2413         args.out_args[0].size = sizeof(outarg);
2414         args.out_args[0].value = &outarg;
2415         err = fuse_simple_request(fc, &args);
2416         if (!err)
2417                 err = convert_fuse_file_lock(fc, &outarg.lk, fl);
2418
2419         return err;
2420 }
2421
2422 static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
2423 {
2424         struct inode *inode = file_inode(file);
2425         struct fuse_conn *fc = get_fuse_conn(inode);
2426         FUSE_ARGS(args);
2427         struct fuse_lk_in inarg;
2428         int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
2429         struct pid *pid = fl->fl_type != F_UNLCK ? task_tgid(current) : NULL;
2430         pid_t pid_nr = pid_nr_ns(pid, fc->pid_ns);
2431         int err;
2432
2433         if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
2434                 /* NLM needs asynchronous locks, which we don't support yet */
2435                 return -ENOLCK;
2436         }
2437
2438         /* Unlock on close is handled by the flush method */
2439         if ((fl->fl_flags & FL_CLOSE_POSIX) == FL_CLOSE_POSIX)
2440                 return 0;
2441
2442         fuse_lk_fill(&args, file, fl, opcode, pid_nr, flock, &inarg);
2443         err = fuse_simple_request(fc, &args);
2444
2445         /* locking is restartable */
2446         if (err == -EINTR)
2447                 err = -ERESTARTSYS;
2448
2449         return err;
2450 }
2451
2452 static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
2453 {
2454         struct inode *inode = file_inode(file);
2455         struct fuse_conn *fc = get_fuse_conn(inode);
2456         int err;
2457
2458         if (cmd == F_CANCELLK) {
2459                 err = 0;
2460         } else if (cmd == F_GETLK) {
2461                 if (fc->no_lock) {
2462                         posix_test_lock(file, fl);
2463                         err = 0;
2464                 } else
2465                         err = fuse_getlk(file, fl);
2466         } else {
2467                 if (fc->no_lock)
2468                         err = posix_lock_file(file, fl, NULL);
2469                 else
2470                         err = fuse_setlk(file, fl, 0);
2471         }
2472         return err;
2473 }
2474
2475 static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
2476 {
2477         struct inode *inode = file_inode(file);
2478         struct fuse_conn *fc = get_fuse_conn(inode);
2479         int err;
2480
2481         if (fc->no_flock) {
2482                 err = locks_lock_file_wait(file, fl);
2483         } else {
2484                 struct fuse_file *ff = file->private_data;
2485
2486                 /* emulate flock with POSIX locks */
2487                 ff->flock = true;
2488                 err = fuse_setlk(file, fl, 1);
2489         }
2490
2491         return err;
2492 }
2493
2494 static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
2495 {
2496         struct inode *inode = mapping->host;
2497         struct fuse_conn *fc = get_fuse_conn(inode);
2498         FUSE_ARGS(args);
2499         struct fuse_bmap_in inarg;
2500         struct fuse_bmap_out outarg;
2501         int err;
2502
2503         if (!inode->i_sb->s_bdev || fc->no_bmap)
2504                 return 0;
2505
2506         memset(&inarg, 0, sizeof(inarg));
2507         inarg.block = block;
2508         inarg.blocksize = inode->i_sb->s_blocksize;
2509         args.opcode = FUSE_BMAP;
2510         args.nodeid = get_node_id(inode);
2511         args.in_numargs = 1;
2512         args.in_args[0].size = sizeof(inarg);
2513         args.in_args[0].value = &inarg;
2514         args.out_numargs = 1;
2515         args.out_args[0].size = sizeof(outarg);
2516         args.out_args[0].value = &outarg;
2517         err = fuse_simple_request(fc, &args);
2518         if (err == -ENOSYS)
2519                 fc->no_bmap = 1;
2520
2521         return err ? 0 : outarg.block;
2522 }
2523
2524 static loff_t fuse_lseek(struct file *file, loff_t offset, int whence)
2525 {
2526         struct inode *inode = file->f_mapping->host;
2527         struct fuse_conn *fc = get_fuse_conn(inode);
2528         struct fuse_file *ff = file->private_data;
2529         FUSE_ARGS(args);
2530         struct fuse_lseek_in inarg = {
2531                 .fh = ff->fh,
2532                 .offset = offset,
2533                 .whence = whence
2534         };
2535         struct fuse_lseek_out outarg;
2536         int err;
2537
2538         if (fc->no_lseek)
2539                 goto fallback;
2540
2541         args.opcode = FUSE_LSEEK;
2542         args.nodeid = ff->nodeid;
2543         args.in_numargs = 1;
2544         args.in_args[0].size = sizeof(inarg);
2545         args.in_args[0].value = &inarg;
2546         args.out_numargs = 1;
2547         args.out_args[0].size = sizeof(outarg);
2548         args.out_args[0].value = &outarg;
2549         err = fuse_simple_request(fc, &args);
2550         if (err) {
2551                 if (err == -ENOSYS) {
2552                         fc->no_lseek = 1;
2553                         goto fallback;
2554                 }
2555                 return err;
2556         }
2557
2558         return vfs_setpos(file, outarg.offset, inode->i_sb->s_maxbytes);
2559
2560 fallback:
2561         err = fuse_update_attributes(inode, file);
2562         if (!err)
2563                 return generic_file_llseek(file, offset, whence);
2564         else
2565                 return err;
2566 }
2567
2568 static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
2569 {
2570         loff_t retval;
2571         struct inode *inode = file_inode(file);
2572
2573         switch (whence) {
2574         case SEEK_SET:
2575         case SEEK_CUR:
2576                  /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
2577                 retval = generic_file_llseek(file, offset, whence);
2578                 break;
2579         case SEEK_END:
2580                 inode_lock(inode);
2581                 retval = fuse_update_attributes(inode, file);
2582                 if (!retval)
2583                         retval = generic_file_llseek(file, offset, whence);
2584                 inode_unlock(inode);
2585                 break;
2586         case SEEK_HOLE:
2587         case SEEK_DATA:
2588                 inode_lock(inode);
2589                 retval = fuse_lseek(file, offset, whence);
2590                 inode_unlock(inode);
2591                 break;
2592         default:
2593                 retval = -EINVAL;
2594         }
2595
2596         return retval;
2597 }
2598
2599 /*
2600  * CUSE servers compiled on 32bit broke on 64bit kernels because the
2601  * ABI was defined to be 'struct iovec' which is different on 32bit
2602  * and 64bit.  Fortunately we can determine which structure the server
2603  * used from the size of the reply.
2604  */
2605 static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
2606                                      size_t transferred, unsigned count,
2607                                      bool is_compat)
2608 {
2609 #ifdef CONFIG_COMPAT
2610         if (count * sizeof(struct compat_iovec) == transferred) {
2611                 struct compat_iovec *ciov = src;
2612                 unsigned i;
2613
2614                 /*
2615                  * With this interface a 32bit server cannot support
2616                  * non-compat (i.e. ones coming from 64bit apps) ioctl
2617                  * requests
2618                  */
2619                 if (!is_compat)
2620                         return -EINVAL;
2621
2622                 for (i = 0; i < count; i++) {
2623                         dst[i].iov_base = compat_ptr(ciov[i].iov_base);
2624                         dst[i].iov_len = ciov[i].iov_len;
2625                 }
2626                 return 0;
2627         }
2628 #endif
2629
2630         if (count * sizeof(struct iovec) != transferred)
2631                 return -EIO;
2632
2633         memcpy(dst, src, transferred);
2634         return 0;
2635 }
2636
2637 /* Make sure iov_length() won't overflow */
2638 static int fuse_verify_ioctl_iov(struct fuse_conn *fc, struct iovec *iov,
2639                                  size_t count)
2640 {
2641         size_t n;
2642         u32 max = fc->max_pages << PAGE_SHIFT;
2643
2644         for (n = 0; n < count; n++, iov++) {
2645                 if (iov->iov_len > (size_t) max)
2646                         return -ENOMEM;
2647                 max -= iov->iov_len;
2648         }
2649         return 0;
2650 }
2651
2652 static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
2653                                  void *src, size_t transferred, unsigned count,
2654                                  bool is_compat)
2655 {
2656         unsigned i;
2657         struct fuse_ioctl_iovec *fiov = src;
2658
2659         if (fc->minor < 16) {
2660                 return fuse_copy_ioctl_iovec_old(dst, src, transferred,
2661                                                  count, is_compat);
2662         }
2663
2664         if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
2665                 return -EIO;
2666
2667         for (i = 0; i < count; i++) {
2668                 /* Did the server supply an inappropriate value? */
2669                 if (fiov[i].base != (unsigned long) fiov[i].base ||
2670                     fiov[i].len != (unsigned long) fiov[i].len)
2671                         return -EIO;
2672
2673                 dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
2674                 dst[i].iov_len = (size_t) fiov[i].len;
2675
2676 #ifdef CONFIG_COMPAT
2677                 if (is_compat &&
2678                     (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
2679                      (compat_size_t) dst[i].iov_len != fiov[i].len))
2680                         return -EIO;
2681 #endif
2682         }
2683
2684         return 0;
2685 }
2686
2687
2688 /*
2689  * For ioctls, there is no generic way to determine how much memory
2690  * needs to be read and/or written.  Furthermore, ioctls are allowed
2691  * to dereference the passed pointer, so the parameter requires deep
2692  * copying but FUSE has no idea whatsoever about what to copy in or
2693  * out.
2694  *
2695  * This is solved by allowing FUSE server to retry ioctl with
2696  * necessary in/out iovecs.  Let's assume the ioctl implementation
2697  * needs to read in the following structure.
2698  *
2699  * struct a {
2700  *      char    *buf;
2701  *      size_t  buflen;
2702  * }
2703  *
2704  * On the first callout to FUSE server, inarg->in_size and
2705  * inarg->out_size will be NULL; then, the server completes the ioctl
2706  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
2707  * the actual iov array to
2708  *
2709  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
2710  *
2711  * which tells FUSE to copy in the requested area and retry the ioctl.
2712  * On the second round, the server has access to the structure and
2713  * from that it can tell what to look for next, so on the invocation,
2714  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
2715  *
2716  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
2717  *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
2718  *
2719  * FUSE will copy both struct a and the pointed buffer from the
2720  * process doing the ioctl and retry ioctl with both struct a and the
2721  * buffer.
2722  *
2723  * This time, FUSE server has everything it needs and completes ioctl
2724  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
2725  *
2726  * Copying data out works the same way.
2727  *
2728  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
2729  * automatically initializes in and out iovs by decoding @cmd with
2730  * _IOC_* macros and the server is not allowed to request RETRY.  This
2731  * limits ioctl data transfers to well-formed ioctls and is the forced
2732  * behavior for all FUSE servers.
2733  */
2734 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
2735                    unsigned int flags)
2736 {
2737         struct fuse_file *ff = file->private_data;
2738         struct fuse_conn *fc = ff->fc;
2739         struct fuse_ioctl_in inarg = {
2740                 .fh = ff->fh,
2741                 .cmd = cmd,
2742                 .arg = arg,
2743                 .flags = flags
2744         };
2745         struct fuse_ioctl_out outarg;
2746         struct iovec *iov_page = NULL;
2747         struct iovec *in_iov = NULL, *out_iov = NULL;
2748         unsigned int in_iovs = 0, out_iovs = 0, max_pages;
2749         size_t in_size, out_size, c;
2750         ssize_t transferred;
2751         int err, i;
2752         struct iov_iter ii;
2753         struct fuse_args_pages ap = {};
2754
2755 #if BITS_PER_LONG == 32
2756         inarg.flags |= FUSE_IOCTL_32BIT;
2757 #else
2758         if (flags & FUSE_IOCTL_COMPAT) {
2759                 inarg.flags |= FUSE_IOCTL_32BIT;
2760 #ifdef CONFIG_X86_X32
2761                 if (in_x32_syscall())
2762                         inarg.flags |= FUSE_IOCTL_COMPAT_X32;
2763 #endif
2764         }
2765 #endif
2766
2767         /* assume all the iovs returned by client always fits in a page */
2768         BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
2769
2770         err = -ENOMEM;
2771         ap.pages = fuse_pages_alloc(fc->max_pages, GFP_KERNEL, &ap.descs);
2772         iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
2773         if (!ap.pages || !iov_page)
2774                 goto out;
2775
2776         fuse_page_descs_length_init(ap.descs, 0, fc->max_pages);
2777
2778         /*
2779          * If restricted, initialize IO parameters as encoded in @cmd.
2780          * RETRY from server is not allowed.
2781          */
2782         if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
2783                 struct iovec *iov = iov_page;
2784
2785                 iov->iov_base = (void __user *)arg;
2786
2787                 switch (cmd) {
2788                 case FS_IOC_GETFLAGS:
2789                 case FS_IOC_SETFLAGS:
2790                         iov->iov_len = sizeof(int);
2791                         break;
2792                 default:
2793                         iov->iov_len = _IOC_SIZE(cmd);
2794                         break;
2795                 }
2796
2797                 if (_IOC_DIR(cmd) & _IOC_WRITE) {
2798                         in_iov = iov;
2799                         in_iovs = 1;
2800                 }
2801
2802                 if (_IOC_DIR(cmd) & _IOC_READ) {
2803                         out_iov = iov;
2804                         out_iovs = 1;
2805                 }
2806         }
2807
2808  retry:
2809         inarg.in_size = in_size = iov_length(in_iov, in_iovs);
2810         inarg.out_size = out_size = iov_length(out_iov, out_iovs);
2811
2812         /*
2813          * Out data can be used either for actual out data or iovs,
2814          * make sure there always is at least one page.
2815          */
2816         out_size = max_t(size_t, out_size, PAGE_SIZE);
2817         max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
2818
2819         /* make sure there are enough buffer pages and init request with them */
2820         err = -ENOMEM;
2821         if (max_pages > fc->max_pages)
2822                 goto out;
2823         while (ap.num_pages < max_pages) {
2824                 ap.pages[ap.num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
2825                 if (!ap.pages[ap.num_pages])
2826                         goto out;
2827                 ap.num_pages++;
2828         }
2829
2830
2831         /* okay, let's send it to the client */
2832         ap.args.opcode = FUSE_IOCTL;
2833         ap.args.nodeid = ff->nodeid;
2834         ap.args.in_numargs = 1;
2835         ap.args.in_args[0].size = sizeof(inarg);
2836         ap.args.in_args[0].value = &inarg;
2837         if (in_size) {
2838                 ap.args.in_numargs++;
2839                 ap.args.in_args[1].size = in_size;
2840                 ap.args.in_pages = true;
2841
2842                 err = -EFAULT;
2843                 iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
2844                 for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
2845                         c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
2846                         if (c != PAGE_SIZE && iov_iter_count(&ii))
2847                                 goto out;
2848                 }
2849         }
2850
2851         ap.args.out_numargs = 2;
2852         ap.args.out_args[0].size = sizeof(outarg);
2853         ap.args.out_args[0].value = &outarg;
2854         ap.args.out_args[1].size = out_size;
2855         ap.args.out_pages = true;
2856         ap.args.out_argvar = true;
2857
2858         transferred = fuse_simple_request(fc, &ap.args);
2859         err = transferred;
2860         if (transferred < 0)
2861                 goto out;
2862
2863         /* did it ask for retry? */
2864         if (outarg.flags & FUSE_IOCTL_RETRY) {
2865                 void *vaddr;
2866
2867                 /* no retry if in restricted mode */
2868                 err = -EIO;
2869                 if (!(flags & FUSE_IOCTL_UNRESTRICTED))
2870                         goto out;
2871
2872                 in_iovs = outarg.in_iovs;
2873                 out_iovs = outarg.out_iovs;
2874
2875                 /*
2876                  * Make sure things are in boundary, separate checks
2877                  * are to protect against overflow.
2878                  */
2879                 err = -ENOMEM;
2880                 if (in_iovs > FUSE_IOCTL_MAX_IOV ||
2881                     out_iovs > FUSE_IOCTL_MAX_IOV ||
2882                     in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
2883                         goto out;
2884
2885                 vaddr = kmap_atomic(ap.pages[0]);
2886                 err = fuse_copy_ioctl_iovec(fc, iov_page, vaddr,
2887                                             transferred, in_iovs + out_iovs,
2888                                             (flags & FUSE_IOCTL_COMPAT) != 0);
2889                 kunmap_atomic(vaddr);
2890                 if (err)
2891                         goto out;
2892
2893                 in_iov = iov_page;
2894                 out_iov = in_iov + in_iovs;
2895
2896                 err = fuse_verify_ioctl_iov(fc, in_iov, in_iovs);
2897                 if (err)
2898                         goto out;
2899
2900                 err = fuse_verify_ioctl_iov(fc, out_iov, out_iovs);
2901                 if (err)
2902                         goto out;
2903
2904                 goto retry;
2905         }
2906
2907         err = -EIO;
2908         if (transferred > inarg.out_size)
2909                 goto out;
2910
2911         err = -EFAULT;
2912         iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
2913         for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
2914                 c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
2915                 if (c != PAGE_SIZE && iov_iter_count(&ii))
2916                         goto out;
2917         }
2918         err = 0;
2919  out:
2920         free_page((unsigned long) iov_page);
2921         while (ap.num_pages)
2922                 __free_page(ap.pages[--ap.num_pages]);
2923         kfree(ap.pages);
2924
2925         return err ? err : outarg.result;
2926 }
2927 EXPORT_SYMBOL_GPL(fuse_do_ioctl);
2928
2929 long fuse_ioctl_common(struct file *file, unsigned int cmd,
2930                        unsigned long arg, unsigned int flags)
2931 {
2932         struct inode *inode = file_inode(file);
2933         struct fuse_conn *fc = get_fuse_conn(inode);
2934
2935         if (!fuse_allow_current_process(fc))
2936                 return -EACCES;
2937
2938         if (fuse_is_bad(inode))
2939                 return -EIO;
2940
2941         return fuse_do_ioctl(file, cmd, arg, flags);
2942 }
2943
2944 static long fuse_file_ioctl(struct file *file, unsigned int cmd,
2945                             unsigned long arg)
2946 {
2947         return fuse_ioctl_common(file, cmd, arg, 0);
2948 }
2949
2950 static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
2951                                    unsigned long arg)
2952 {
2953         return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
2954 }
2955
2956 /*
2957  * All files which have been polled are linked to RB tree
2958  * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
2959  * find the matching one.
2960  */
2961 static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
2962                                               struct rb_node **parent_out)
2963 {
2964         struct rb_node **link = &fc->polled_files.rb_node;
2965         struct rb_node *last = NULL;
2966
2967         while (*link) {
2968                 struct fuse_file *ff;
2969
2970                 last = *link;
2971                 ff = rb_entry(last, struct fuse_file, polled_node);
2972
2973                 if (kh < ff->kh)
2974                         link = &last->rb_left;
2975                 else if (kh > ff->kh)
2976                         link = &last->rb_right;
2977                 else
2978                         return link;
2979         }
2980
2981         if (parent_out)
2982                 *parent_out = last;
2983         return link;
2984 }
2985
2986 /*
2987  * The file is about to be polled.  Make sure it's on the polled_files
2988  * RB tree.  Note that files once added to the polled_files tree are
2989  * not removed before the file is released.  This is because a file
2990  * polled once is likely to be polled again.
2991  */
2992 static void fuse_register_polled_file(struct fuse_conn *fc,
2993                                       struct fuse_file *ff)
2994 {
2995         spin_lock(&fc->lock);
2996         if (RB_EMPTY_NODE(&ff->polled_node)) {
2997                 struct rb_node **link, *parent;
2998
2999                 link = fuse_find_polled_node(fc, ff->kh, &parent);
3000                 BUG_ON(*link);
3001                 rb_link_node(&ff->polled_node, parent, link);
3002                 rb_insert_color(&ff->polled_node, &fc->polled_files);
3003         }
3004         spin_unlock(&fc->lock);
3005 }
3006
3007 __poll_t fuse_file_poll(struct file *file, poll_table *wait)
3008 {
3009         struct fuse_file *ff = file->private_data;
3010         struct fuse_conn *fc = ff->fc;
3011         struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
3012         struct fuse_poll_out outarg;
3013         FUSE_ARGS(args);
3014         int err;
3015
3016         if (fc->no_poll)
3017                 return DEFAULT_POLLMASK;
3018
3019         poll_wait(file, &ff->poll_wait, wait);
3020         inarg.events = mangle_poll(poll_requested_events(wait));
3021
3022         /*
3023          * Ask for notification iff there's someone waiting for it.
3024          * The client may ignore the flag and always notify.
3025          */
3026         if (waitqueue_active(&ff->poll_wait)) {
3027                 inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
3028                 fuse_register_polled_file(fc, ff);
3029         }
3030
3031         args.opcode = FUSE_POLL;
3032         args.nodeid = ff->nodeid;
3033         args.in_numargs = 1;
3034         args.in_args[0].size = sizeof(inarg);
3035         args.in_args[0].value = &inarg;
3036         args.out_numargs = 1;
3037         args.out_args[0].size = sizeof(outarg);
3038         args.out_args[0].value = &outarg;
3039         err = fuse_simple_request(fc, &args);
3040
3041         if (!err)
3042                 return demangle_poll(outarg.revents);
3043         if (err == -ENOSYS) {
3044                 fc->no_poll = 1;
3045                 return DEFAULT_POLLMASK;
3046         }
3047         return EPOLLERR;
3048 }
3049 EXPORT_SYMBOL_GPL(fuse_file_poll);
3050
3051 /*
3052  * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
3053  * wakes up the poll waiters.
3054  */
3055 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
3056                             struct fuse_notify_poll_wakeup_out *outarg)
3057 {
3058         u64 kh = outarg->kh;
3059         struct rb_node **link;
3060
3061         spin_lock(&fc->lock);
3062
3063         link = fuse_find_polled_node(fc, kh, NULL);
3064         if (*link) {
3065                 struct fuse_file *ff;
3066
3067                 ff = rb_entry(*link, struct fuse_file, polled_node);
3068                 wake_up_interruptible_sync(&ff->poll_wait);
3069         }
3070
3071         spin_unlock(&fc->lock);
3072         return 0;
3073 }
3074
3075 static void fuse_do_truncate(struct file *file)
3076 {
3077         struct inode *inode = file->f_mapping->host;
3078         struct iattr attr;
3079
3080         attr.ia_valid = ATTR_SIZE;
3081         attr.ia_size = i_size_read(inode);
3082
3083         attr.ia_file = file;
3084         attr.ia_valid |= ATTR_FILE;
3085
3086         fuse_do_setattr(file_dentry(file), &attr, file);
3087 }
3088
3089 static inline loff_t fuse_round_up(struct fuse_conn *fc, loff_t off)
3090 {
3091         return round_up(off, fc->max_pages << PAGE_SHIFT);
3092 }
3093
3094 static ssize_t
3095 fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
3096 {
3097         DECLARE_COMPLETION_ONSTACK(wait);
3098         ssize_t ret = 0;
3099         struct file *file = iocb->ki_filp;
3100         struct fuse_file *ff = file->private_data;
3101         loff_t pos = 0;
3102         struct inode *inode;
3103         loff_t i_size;
3104         size_t count = iov_iter_count(iter), shortened = 0;
3105         loff_t offset = iocb->ki_pos;
3106         struct fuse_io_priv *io;
3107
3108         pos = offset;
3109         inode = file->f_mapping->host;
3110         i_size = i_size_read(inode);
3111
3112         if ((iov_iter_rw(iter) == READ) && (offset >= i_size))
3113                 return 0;
3114
3115         io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
3116         if (!io)
3117                 return -ENOMEM;
3118         spin_lock_init(&io->lock);
3119         kref_init(&io->refcnt);
3120         io->reqs = 1;
3121         io->bytes = -1;
3122         io->size = 0;
3123         io->offset = offset;
3124         io->write = (iov_iter_rw(iter) == WRITE);
3125         io->err = 0;
3126         /*
3127          * By default, we want to optimize all I/Os with async request
3128          * submission to the client filesystem if supported.
3129          */
3130         io->async = ff->fc->async_dio;
3131         io->iocb = iocb;
3132         io->blocking = is_sync_kiocb(iocb);
3133
3134         /* optimization for short read */
3135         if (io->async && !io->write && offset + count > i_size) {
3136                 iov_iter_truncate(iter, fuse_round_up(ff->fc, i_size - offset));
3137                 shortened = count - iov_iter_count(iter);
3138                 count -= shortened;
3139         }
3140
3141         /*
3142          * We cannot asynchronously extend the size of a file.
3143          * In such case the aio will behave exactly like sync io.
3144          */
3145         if ((offset + count > i_size) && io->write)
3146                 io->blocking = true;
3147
3148         if (io->async && io->blocking) {
3149                 /*
3150                  * Additional reference to keep io around after
3151                  * calling fuse_aio_complete()
3152                  */
3153                 kref_get(&io->refcnt);
3154                 io->done = &wait;
3155         }
3156
3157         if (iov_iter_rw(iter) == WRITE) {
3158                 ret = fuse_direct_io(io, iter, &pos, FUSE_DIO_WRITE);
3159                 fuse_invalidate_attr(inode);
3160         } else {
3161                 ret = __fuse_direct_read(io, iter, &pos);
3162         }
3163         iov_iter_reexpand(iter, iov_iter_count(iter) + shortened);
3164
3165         if (io->async) {
3166                 bool blocking = io->blocking;
3167
3168                 fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
3169
3170                 /* we have a non-extending, async request, so return */
3171                 if (!blocking)
3172                         return -EIOCBQUEUED;
3173
3174                 wait_for_completion(&wait);
3175                 ret = fuse_get_res_by_io(io);
3176         }
3177
3178         kref_put(&io->refcnt, fuse_io_release);
3179
3180         if (iov_iter_rw(iter) == WRITE) {
3181                 if (ret > 0)
3182                         fuse_write_update_size(inode, pos);
3183                 else if (ret < 0 && offset + count > i_size)
3184                         fuse_do_truncate(file);
3185         }
3186
3187         return ret;
3188 }
3189
3190 static int fuse_writeback_range(struct inode *inode, loff_t start, loff_t end)
3191 {
3192         int err = filemap_write_and_wait_range(inode->i_mapping, start, LLONG_MAX);
3193
3194         if (!err)
3195                 fuse_sync_writes(inode);
3196
3197         return err;
3198 }
3199
3200 static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
3201                                 loff_t length)
3202 {
3203         struct fuse_file *ff = file->private_data;
3204         struct inode *inode = file_inode(file);
3205         struct fuse_inode *fi = get_fuse_inode(inode);
3206         struct fuse_conn *fc = ff->fc;
3207         FUSE_ARGS(args);
3208         struct fuse_fallocate_in inarg = {
3209                 .fh = ff->fh,
3210                 .offset = offset,
3211                 .length = length,
3212                 .mode = mode
3213         };
3214         int err;
3215         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
3216                 return -EOPNOTSUPP;
3217
3218         if (fc->no_fallocate)
3219                 return -EOPNOTSUPP;
3220
3221         inode_lock(inode);
3222         if (mode & FALLOC_FL_PUNCH_HOLE) {
3223                 loff_t endbyte = offset + length - 1;
3224
3225                 err = fuse_writeback_range(inode, offset, endbyte);
3226                 if (err)
3227                         goto out;
3228         }
3229
3230         if (!(mode & FALLOC_FL_KEEP_SIZE) &&
3231             offset + length > i_size_read(inode)) {
3232                 err = inode_newsize_ok(inode, offset + length);
3233                 if (err)
3234                         goto out;
3235         }
3236
3237         err = file_modified(file);
3238         if (err)
3239                 goto out;
3240
3241         if (!(mode & FALLOC_FL_KEEP_SIZE))
3242                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3243
3244         args.opcode = FUSE_FALLOCATE;
3245         args.nodeid = ff->nodeid;
3246         args.in_numargs = 1;
3247         args.in_args[0].size = sizeof(inarg);
3248         args.in_args[0].value = &inarg;
3249         err = fuse_simple_request(fc, &args);
3250         if (err == -ENOSYS) {
3251                 fc->no_fallocate = 1;
3252                 err = -EOPNOTSUPP;
3253         }
3254         if (err)
3255                 goto out;
3256
3257         /* we could have extended the file */
3258         if (!(mode & FALLOC_FL_KEEP_SIZE)) {
3259                 bool changed = fuse_write_update_size(inode, offset + length);
3260
3261                 if (changed && fc->writeback_cache)
3262                         file_update_time(file);
3263         }
3264
3265         if (mode & FALLOC_FL_PUNCH_HOLE)
3266                 truncate_pagecache_range(inode, offset, offset + length - 1);
3267
3268         fuse_invalidate_attr(inode);
3269
3270 out:
3271         if (!(mode & FALLOC_FL_KEEP_SIZE))
3272                 clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3273
3274         inode_unlock(inode);
3275
3276         return err;
3277 }
3278
3279 static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
3280                                       struct file *file_out, loff_t pos_out,
3281                                       size_t len, unsigned int flags)
3282 {
3283         struct fuse_file *ff_in = file_in->private_data;
3284         struct fuse_file *ff_out = file_out->private_data;
3285         struct inode *inode_in = file_inode(file_in);
3286         struct inode *inode_out = file_inode(file_out);
3287         struct fuse_inode *fi_out = get_fuse_inode(inode_out);
3288         struct fuse_conn *fc = ff_in->fc;
3289         FUSE_ARGS(args);
3290         struct fuse_copy_file_range_in inarg = {
3291                 .fh_in = ff_in->fh,
3292                 .off_in = pos_in,
3293                 .nodeid_out = ff_out->nodeid,
3294                 .fh_out = ff_out->fh,
3295                 .off_out = pos_out,
3296                 .len = len,
3297                 .flags = flags
3298         };
3299         struct fuse_write_out outarg;
3300         ssize_t err;
3301         /* mark unstable when write-back is not used, and file_out gets
3302          * extended */
3303         bool is_unstable = (!fc->writeback_cache) &&
3304                            ((pos_out + len) > inode_out->i_size);
3305
3306         if (fc->no_copy_file_range)
3307                 return -EOPNOTSUPP;
3308
3309         if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
3310                 return -EXDEV;
3311
3312         inode_lock(inode_in);
3313         err = fuse_writeback_range(inode_in, pos_in, pos_in + len - 1);
3314         inode_unlock(inode_in);
3315         if (err)
3316                 return err;
3317
3318         inode_lock(inode_out);
3319
3320         err = file_modified(file_out);
3321         if (err)
3322                 goto out;
3323
3324         /*
3325          * Write out dirty pages in the destination file before sending the COPY
3326          * request to userspace.  After the request is completed, truncate off
3327          * pages (including partial ones) from the cache that have been copied,
3328          * since these contain stale data at that point.
3329          *
3330          * This should be mostly correct, but if the COPY writes to partial
3331          * pages (at the start or end) and the parts not covered by the COPY are
3332          * written through a memory map after calling fuse_writeback_range(),
3333          * then these partial page modifications will be lost on truncation.
3334          *
3335          * It is unlikely that someone would rely on such mixed style
3336          * modifications.  Yet this does give less guarantees than if the
3337          * copying was performed with write(2).
3338          *
3339          * To fix this a i_mmap_sem style lock could be used to prevent new
3340          * faults while the copy is ongoing.
3341          */
3342         err = fuse_writeback_range(inode_out, pos_out, pos_out + len - 1);
3343         if (err)
3344                 goto out;
3345
3346         if (is_unstable)
3347                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
3348
3349         args.opcode = FUSE_COPY_FILE_RANGE;
3350         args.nodeid = ff_in->nodeid;
3351         args.in_numargs = 1;
3352         args.in_args[0].size = sizeof(inarg);
3353         args.in_args[0].value = &inarg;
3354         args.out_numargs = 1;
3355         args.out_args[0].size = sizeof(outarg);
3356         args.out_args[0].value = &outarg;
3357         err = fuse_simple_request(fc, &args);
3358         if (err == -ENOSYS) {
3359                 fc->no_copy_file_range = 1;
3360                 err = -EOPNOTSUPP;
3361         }
3362         if (err)
3363                 goto out;
3364
3365         truncate_inode_pages_range(inode_out->i_mapping,
3366                                    ALIGN_DOWN(pos_out, PAGE_SIZE),
3367                                    ALIGN(pos_out + outarg.size, PAGE_SIZE) - 1);
3368
3369         if (fc->writeback_cache) {
3370                 fuse_write_update_size(inode_out, pos_out + outarg.size);
3371                 file_update_time(file_out);
3372         }
3373
3374         fuse_invalidate_attr(inode_out);
3375
3376         err = outarg.size;
3377 out:
3378         if (is_unstable)
3379                 clear_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
3380
3381         inode_unlock(inode_out);
3382         file_accessed(file_in);
3383
3384         return err;
3385 }
3386
3387 static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
3388                                     struct file *dst_file, loff_t dst_off,
3389                                     size_t len, unsigned int flags)
3390 {
3391         ssize_t ret;
3392
3393         ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off,
3394                                      len, flags);
3395
3396         if (ret == -EOPNOTSUPP || ret == -EXDEV)
3397                 ret = generic_copy_file_range(src_file, src_off, dst_file,
3398                                               dst_off, len, flags);
3399         return ret;
3400 }
3401
3402 static const struct file_operations fuse_file_operations = {
3403         .llseek         = fuse_file_llseek,
3404         .read_iter      = fuse_file_read_iter,
3405         .write_iter     = fuse_file_write_iter,
3406         .mmap           = fuse_file_mmap,
3407         .open           = fuse_open,
3408         .flush          = fuse_flush,
3409         .release        = fuse_release,
3410         .fsync          = fuse_fsync,
3411         .lock           = fuse_file_lock,
3412         .flock          = fuse_file_flock,
3413         .splice_read    = generic_file_splice_read,
3414         .splice_write   = iter_file_splice_write,
3415         .unlocked_ioctl = fuse_file_ioctl,
3416         .compat_ioctl   = fuse_file_compat_ioctl,
3417         .poll           = fuse_file_poll,
3418         .fallocate      = fuse_file_fallocate,
3419         .copy_file_range = fuse_copy_file_range,
3420 };
3421
3422 static const struct address_space_operations fuse_file_aops  = {
3423         .readpage       = fuse_readpage,
3424         .writepage      = fuse_writepage,
3425         .writepages     = fuse_writepages,
3426         .launder_page   = fuse_launder_page,
3427         .readpages      = fuse_readpages,
3428         .set_page_dirty = __set_page_dirty_nobuffers,
3429         .bmap           = fuse_bmap,
3430         .direct_IO      = fuse_direct_IO,
3431         .write_begin    = fuse_write_begin,
3432         .write_end      = fuse_write_end,
3433 };
3434
3435 void fuse_init_file_inode(struct inode *inode)
3436 {
3437         struct fuse_inode *fi = get_fuse_inode(inode);
3438
3439         inode->i_fop = &fuse_file_operations;
3440         inode->i_data.a_ops = &fuse_file_aops;
3441
3442         INIT_LIST_HEAD(&fi->write_files);
3443         INIT_LIST_HEAD(&fi->queued_writes);
3444         fi->writectr = 0;
3445         init_waitqueue_head(&fi->page_waitq);
3446         INIT_LIST_HEAD(&fi->writepages);
3447 }