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
  16 static const struct file_operations fuse_direct_io_file_operations;
  17
  18 static int fuse_send_open(struct inode *inode, struct file *file, int isdir,
  19                           struct fuse_open_out *outargp)
  20 {
  21         struct fuse_conn *fc = get_fuse_conn(inode);
  22         struct fuse_open_in inarg;
  23         struct fuse_req *req;
  24         int err;
  25
  26         req = fuse_get_req(fc);
  27         if (IS_ERR(req))
  28                 return PTR_ERR(req);
  29
  30         memset(&inarg, 0, sizeof(inarg));
  31         inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
  32         if (!fc->atomic_o_trunc)
  33                 inarg.flags &= ~O_TRUNC;
  34         req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
  35         req->in.h.nodeid = get_node_id(inode);
  36         req->in.numargs = 1;
  37         req->in.args[0].size = sizeof(inarg);
  38         req->in.args[0].value = &inarg;
  39         req->out.numargs = 1;
  40         req->out.args[0].size = sizeof(*outargp);
  41         req->out.args[0].value = outargp;
  42         fuse_request_send(fc, req);
  43         err = req->out.h.error;
  44         fuse_put_request(fc, req);
  45
  46         return err;
  47 }
  48
  49 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
  50 {
  51         struct fuse_file *ff;
  52         ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
  53         if (ff) {
  54                 ff->reserved_req = fuse_request_alloc();
  55                 if (!ff->reserved_req) {
  56                         kfree(ff);
  57                         return NULL;
  58                 } else {
  59                         INIT_LIST_HEAD(&ff->write_entry);
  60                         atomic_set(&ff->count, 0);
  61                         spin_lock(&fc->lock);
  62                         ff->kh = ++fc->khctr;
  63                         spin_unlock(&fc->lock);
  64                 }
  65                 RB_CLEAR_NODE(&ff->polled_node);
  66                 init_waitqueue_head(&ff->poll_wait);
  67         }
  68         return ff;
  69 }
  70
  71 void fuse_file_free(struct fuse_file *ff)
  72 {
  73         fuse_request_free(ff->reserved_req);
  74         kfree(ff);
  75 }
  76
  77 static struct fuse_file *fuse_file_get(struct fuse_file *ff)
  78 {
  79         atomic_inc(&ff->count);
  80         return ff;
  81 }
  82
  83 static void fuse_release_end(struct fuse_conn *fc, struct fuse_req *req)
  84 {
  85         dput(req->misc.release.dentry);
  86         mntput(req->misc.release.vfsmount);
  87 }
  88
  89 static void fuse_file_put(struct fuse_file *ff)
  90 {
  91         if (atomic_dec_and_test(&ff->count)) {
  92                 struct fuse_req *req = ff->reserved_req;
  93                 struct inode *inode = req->misc.release.dentry->d_inode;
  94                 struct fuse_conn *fc = get_fuse_conn(inode);
  95                 req->end = fuse_release_end;
  96                 fuse_request_send_background(fc, req);
  97                 kfree(ff);
  98         }
  99 }
 100
 101 void fuse_finish_open(struct inode *inode, struct file *file,
 102                       struct fuse_file *ff, struct fuse_open_out *outarg)
 103 {
 104         if (outarg->open_flags & FOPEN_DIRECT_IO)
 105                 file->f_op = &fuse_direct_io_file_operations;
 106         if (!(outarg->open_flags & FOPEN_KEEP_CACHE))
 107                 invalidate_inode_pages2(inode->i_mapping);
 108         if (outarg->open_flags & FOPEN_NONSEEKABLE)
 109                 nonseekable_open(inode, file);
 110         ff->fh = outarg->fh;
 111         file->private_data = fuse_file_get(ff);
 112 }
 113
 114 int fuse_open_common(struct inode *inode, struct file *file, int isdir)
 115 {
 116         struct fuse_conn *fc = get_fuse_conn(inode);
 117         struct fuse_open_out outarg;
 118         struct fuse_file *ff;
 119         int err;
 120
 121         /* VFS checks this, but only _after_ ->open() */
 122         if (file->f_flags & O_DIRECT)
 123                 return -EINVAL;
 124
 125         err = generic_file_open(inode, file);
 126         if (err)
 127                 return err;
 128
 129         ff = fuse_file_alloc(fc);
 130         if (!ff)
 131                 return -ENOMEM;
 132
 133         err = fuse_send_open(inode, file, isdir, &outarg);
 134         if (err)
 135                 fuse_file_free(ff);
 136         else {
 137                 if (isdir)
 138                         outarg.open_flags &= ~FOPEN_DIRECT_IO;
 139                 fuse_finish_open(inode, file, ff, &outarg);
 140         }
 141
 142         return err;
 143 }
 144
 145 void fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode)
 146 {
 147         struct fuse_req *req = ff->reserved_req;
 148         struct fuse_release_in *inarg = &req->misc.release.in;
 149
 150         inarg->fh = ff->fh;
 151         inarg->flags = flags;
 152         req->in.h.opcode = opcode;
 153         req->in.h.nodeid = nodeid;
 154         req->in.numargs = 1;
 155         req->in.args[0].size = sizeof(struct fuse_release_in);
 156         req->in.args[0].value = inarg;
 157 }
 158
 159 int fuse_release_common(struct inode *inode, struct file *file, int isdir)
 160 {
 161         struct fuse_file *ff = file->private_data;
 162         if (ff) {
 163                 struct fuse_conn *fc = get_fuse_conn(inode);
 164                 struct fuse_req *req = ff->reserved_req;
 165
 166                 fuse_release_fill(ff, get_node_id(inode), file->f_flags,
 167                                   isdir ? FUSE_RELEASEDIR : FUSE_RELEASE);
 168
 169                 /* Hold vfsmount and dentry until release is finished */
 170                 req->misc.release.vfsmount = mntget(file->f_path.mnt);
 171                 req->misc.release.dentry = dget(file->f_path.dentry);
 172
 173                 spin_lock(&fc->lock);
 174                 list_del(&ff->write_entry);
 175                 if (!RB_EMPTY_NODE(&ff->polled_node))
 176                         rb_erase(&ff->polled_node, &fc->polled_files);
 177                 spin_unlock(&fc->lock);
 178
 179                 wake_up_interruptible_sync(&ff->poll_wait);
 180                 /*
 181                  * Normally this will send the RELEASE request,
 182                  * however if some asynchronous READ or WRITE requests
 183                  * are outstanding, the sending will be delayed
 184                  */
 185                 fuse_file_put(ff);
 186         }
 187
 188         /* Return value is ignored by VFS */
 189         return 0;
 190 }
 191
 192 static int fuse_open(struct inode *inode, struct file *file)
 193 {
 194         return fuse_open_common(inode, file, 0);
 195 }
 196
 197 static int fuse_release(struct inode *inode, struct file *file)
 198 {
 199         return fuse_release_common(inode, file, 0);
 200 }
 201
 202 /*
 203  * Scramble the ID space with XTEA, so that the value of the files_struct
 204  * pointer is not exposed to userspace.
 205  */
 206 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
 207 {
 208         u32 *k = fc->scramble_key;
 209         u64 v = (unsigned long) id;
 210         u32 v0 = v;
 211         u32 v1 = v >> 32;
 212         u32 sum = 0;
 213         int i;
 214
 215         for (i = 0; i < 32; i++) {
 216                 v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
 217                 sum += 0x9E3779B9;
 218                 v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
 219         }
 220
 221         return (u64) v0 + ((u64) v1 << 32);
 222 }
 223
 224 /*
 225  * Check if page is under writeback
 226  *
 227  * This is currently done by walking the list of writepage requests
 228  * for the inode, which can be pretty inefficient.
 229  */
 230 static bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
 231 {
 232         struct fuse_conn *fc = get_fuse_conn(inode);
 233         struct fuse_inode *fi = get_fuse_inode(inode);
 234         struct fuse_req *req;
 235         bool found = false;
 236
 237         spin_lock(&fc->lock);
 238         list_for_each_entry(req, &fi->writepages, writepages_entry) {
 239                 pgoff_t curr_index;
 240
 241                 BUG_ON(req->inode != inode);
 242                 curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT;
 243                 if (curr_index == index) {
 244                         found = true;
 245                         break;
 246                 }
 247         }
 248         spin_unlock(&fc->lock);
 249
 250         return found;
 251 }
 252
 253 /*
 254  * Wait for page writeback to be completed.
 255  *
 256  * Since fuse doesn't rely on the VM writeback tracking, this has to
 257  * use some other means.
 258  */
 259 static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
 260 {
 261         struct fuse_inode *fi = get_fuse_inode(inode);
 262
 263         wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
 264         return 0;
 265 }
 266
 267 static int fuse_flush(struct file *file, fl_owner_t id)
 268 {
 269         struct inode *inode = file->f_path.dentry->d_inode;
 270         struct fuse_conn *fc = get_fuse_conn(inode);
 271         struct fuse_file *ff = file->private_data;
 272         struct fuse_req *req;
 273         struct fuse_flush_in inarg;
 274         int err;
 275
 276         if (is_bad_inode(inode))
 277                 return -EIO;
 278
 279         if (fc->no_flush)
 280                 return 0;
 281
 282         req = fuse_get_req_nofail(fc, file);
 283         memset(&inarg, 0, sizeof(inarg));
 284         inarg.fh = ff->fh;
 285         inarg.lock_owner = fuse_lock_owner_id(fc, id);
 286         req->in.h.opcode = FUSE_FLUSH;
 287         req->in.h.nodeid = get_node_id(inode);
 288         req->in.numargs = 1;
 289         req->in.args[0].size = sizeof(inarg);
 290         req->in.args[0].value = &inarg;
 291         req->force = 1;
 292         fuse_request_send(fc, req);
 293         err = req->out.h.error;
 294         fuse_put_request(fc, req);
 295         if (err == -ENOSYS) {
 296                 fc->no_flush = 1;
 297                 err = 0;
 298         }
 299         return err;
 300 }
 301
 302 /*
 303  * Wait for all pending writepages on the inode to finish.
 304  *
 305  * This is currently done by blocking further writes with FUSE_NOWRITE
 306  * and waiting for all sent writes to complete.
 307  *
 308  * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
 309  * could conflict with truncation.
 310  */
 311 static void fuse_sync_writes(struct inode *inode)
 312 {
 313         fuse_set_nowrite(inode);
 314         fuse_release_nowrite(inode);
 315 }
 316
 317 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 318                       int isdir)
 319 {
 320         struct inode *inode = de->d_inode;
 321         struct fuse_conn *fc = get_fuse_conn(inode);
 322         struct fuse_file *ff = file->private_data;
 323         struct fuse_req *req;
 324         struct fuse_fsync_in inarg;
 325         int err;
 326
 327         if (is_bad_inode(inode))
 328                 return -EIO;
 329
 330         if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
 331                 return 0;
 332
 333         /*
 334          * Start writeback against all dirty pages of the inode, then
 335          * wait for all outstanding writes, before sending the FSYNC
 336          * request.
 337          */
 338         err = write_inode_now(inode, 0);
 339         if (err)
 340                 return err;
 341
 342         fuse_sync_writes(inode);
 343
 344         req = fuse_get_req(fc);
 345         if (IS_ERR(req))
 346                 return PTR_ERR(req);
 347
 348         memset(&inarg, 0, sizeof(inarg));
 349         inarg.fh = ff->fh;
 350         inarg.fsync_flags = datasync ? 1 : 0;
 351         req->in.h.opcode = isdir ? FUSE_FSYNCDIR : FUSE_FSYNC;
 352         req->in.h.nodeid = get_node_id(inode);
 353         req->in.numargs = 1;
 354         req->in.args[0].size = sizeof(inarg);
 355         req->in.args[0].value = &inarg;
 356         fuse_request_send(fc, req);
 357         err = req->out.h.error;
 358         fuse_put_request(fc, req);
 359         if (err == -ENOSYS) {
 360                 if (isdir)
 361                         fc->no_fsyncdir = 1;
 362                 else
 363                         fc->no_fsync = 1;
 364                 err = 0;
 365         }
 366         return err;
 367 }
 368
 369 static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
 370 {
 371         return fuse_fsync_common(file, de, datasync, 0);
 372 }
 373
 374 void fuse_read_fill(struct fuse_req *req, struct file *file,
 375                     struct inode *inode, loff_t pos, size_t count, int opcode)
 376 {
 377         struct fuse_read_in *inarg = &req->misc.read.in;
 378         struct fuse_file *ff = file->private_data;
 379
 380         inarg->fh = ff->fh;
 381         inarg->offset = pos;
 382         inarg->size = count;
 383         inarg->flags = file->f_flags;
 384         req->in.h.opcode = opcode;
 385         req->in.h.nodeid = get_node_id(inode);
 386         req->in.numargs = 1;
 387         req->in.args[0].size = sizeof(struct fuse_read_in);
 388         req->in.args[0].value = inarg;
 389         req->out.argvar = 1;
 390         req->out.numargs = 1;
 391         req->out.args[0].size = count;
 392 }
 393
 394 static size_t fuse_send_read(struct fuse_req *req, struct file *file,
 395                              struct inode *inode, loff_t pos, size_t count,
 396                              fl_owner_t owner)
 397 {
 398         struct fuse_conn *fc = get_fuse_conn(inode);
 399
 400         fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
 401         if (owner != NULL) {
 402                 struct fuse_read_in *inarg = &req->misc.read.in;
 403
 404                 inarg->read_flags |= FUSE_READ_LOCKOWNER;
 405                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 406         }
 407         fuse_request_send(fc, req);
 408         return req->out.args[0].size;
 409 }
 410
 411 static void fuse_read_update_size(struct inode *inode, loff_t size,
 412                                   u64 attr_ver)
 413 {
 414         struct fuse_conn *fc = get_fuse_conn(inode);
 415         struct fuse_inode *fi = get_fuse_inode(inode);
 416
 417         spin_lock(&fc->lock);
 418         if (attr_ver == fi->attr_version && size < inode->i_size) {
 419                 fi->attr_version = ++fc->attr_version;
 420                 i_size_write(inode, size);
 421         }
 422         spin_unlock(&fc->lock);
 423 }
 424
 425 static int fuse_readpage(struct file *file, struct page *page)
 426 {
 427         struct inode *inode = page->mapping->host;
 428         struct fuse_conn *fc = get_fuse_conn(inode);
 429         struct fuse_req *req;
 430         size_t num_read;
 431         loff_t pos = page_offset(page);
 432         size_t count = PAGE_CACHE_SIZE;
 433         u64 attr_ver;
 434         int err;
 435
 436         err = -EIO;
 437         if (is_bad_inode(inode))
 438                 goto out;
 439
 440         /*
 441          * Page writeback can extend beyond the liftime of the
 442          * page-cache page, so make sure we read a properly synced
 443          * page.
 444          */
 445         fuse_wait_on_page_writeback(inode, page->index);
 446
 447         req = fuse_get_req(fc);
 448         err = PTR_ERR(req);
 449         if (IS_ERR(req))
 450                 goto out;
 451
 452         attr_ver = fuse_get_attr_version(fc);
 453
 454         req->out.page_zeroing = 1;
 455         req->out.argpages = 1;
 456         req->num_pages = 1;
 457         req->pages[0] = page;
 458         num_read = fuse_send_read(req, file, inode, pos, count, NULL);
 459         err = req->out.h.error;
 460         fuse_put_request(fc, req);
 461
 462         if (!err) {
 463                 /*
 464                  * Short read means EOF.  If file size is larger, truncate it
 465                  */
 466                 if (num_read < count)
 467                         fuse_read_update_size(inode, pos + num_read, attr_ver);
 468
 469                 SetPageUptodate(page);
 470         }
 471
 472         fuse_invalidate_attr(inode); /* atime changed */
 473  out:
 474         unlock_page(page);
 475         return err;
 476 }
 477
 478 static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
 479 {
 480         int i;
 481         size_t count = req->misc.read.in.size;
 482         size_t num_read = req->out.args[0].size;
 483         struct inode *inode = req->pages[0]->mapping->host;
 484
 485         /*
 486          * Short read means EOF.  If file size is larger, truncate it
 487          */
 488         if (!req->out.h.error && num_read < count) {
 489                 loff_t pos = page_offset(req->pages[0]) + num_read;
 490                 fuse_read_update_size(inode, pos, req->misc.read.attr_ver);
 491         }
 492
 493         fuse_invalidate_attr(inode); /* atime changed */
 494
 495         for (i = 0; i < req->num_pages; i++) {
 496                 struct page *page = req->pages[i];
 497                 if (!req->out.h.error)
 498                         SetPageUptodate(page);
 499                 else
 500                         SetPageError(page);
 501                 unlock_page(page);
 502         }
 503         if (req->ff)
 504                 fuse_file_put(req->ff);
 505 }
 506
 507 static void fuse_send_readpages(struct fuse_req *req, struct file *file,
 508                                 struct inode *inode)
 509 {
 510         struct fuse_conn *fc = get_fuse_conn(inode);
 511         loff_t pos = page_offset(req->pages[0]);
 512         size_t count = req->num_pages << PAGE_CACHE_SHIFT;
 513
 514         req->out.argpages = 1;
 515         req->out.page_zeroing = 1;
 516         fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
 517         req->misc.read.attr_ver = fuse_get_attr_version(fc);
 518         if (fc->async_read) {
 519                 struct fuse_file *ff = file->private_data;
 520                 req->ff = fuse_file_get(ff);
 521                 req->end = fuse_readpages_end;
 522                 fuse_request_send_background(fc, req);
 523         } else {
 524                 fuse_request_send(fc, req);
 525                 fuse_readpages_end(fc, req);
 526                 fuse_put_request(fc, req);
 527         }
 528 }
 529
 530 struct fuse_fill_data {
 531         struct fuse_req *req;
 532         struct file *file;
 533         struct inode *inode;
 534 };
 535
 536 static int fuse_readpages_fill(void *_data, struct page *page)
 537 {
 538         struct fuse_fill_data *data = _data;
 539         struct fuse_req *req = data->req;
 540         struct inode *inode = data->inode;
 541         struct fuse_conn *fc = get_fuse_conn(inode);
 542
 543         fuse_wait_on_page_writeback(inode, page->index);
 544
 545         if (req->num_pages &&
 546             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 547              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 548              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 549                 fuse_send_readpages(req, data->file, inode);
 550                 data->req = req = fuse_get_req(fc);
 551                 if (IS_ERR(req)) {
 552                         unlock_page(page);
 553                         return PTR_ERR(req);
 554                 }
 555         }
 556         req->pages[req->num_pages] = page;
 557         req->num_pages++;
 558         return 0;
 559 }
 560
 561 static int fuse_readpages(struct file *file, struct address_space *mapping,
 562                           struct list_head *pages, unsigned nr_pages)
 563 {
 564         struct inode *inode = mapping->host;
 565         struct fuse_conn *fc = get_fuse_conn(inode);
 566         struct fuse_fill_data data;
 567         int err;
 568
 569         err = -EIO;
 570         if (is_bad_inode(inode))
 571                 goto out;
 572
 573         data.file = file;
 574         data.inode = inode;
 575         data.req = fuse_get_req(fc);
 576         err = PTR_ERR(data.req);
 577         if (IS_ERR(data.req))
 578                 goto out;
 579
 580         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 581         if (!err) {
 582                 if (data.req->num_pages)
 583                         fuse_send_readpages(data.req, file, inode);
 584                 else
 585                         fuse_put_request(fc, data.req);
 586         }
 587 out:
 588         return err;
 589 }
 590
 591 static ssize_t fuse_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 592                                   unsigned long nr_segs, loff_t pos)
 593 {
 594         struct inode *inode = iocb->ki_filp->f_mapping->host;
 595
 596         if (pos + iov_length(iov, nr_segs) > i_size_read(inode)) {
 597                 int err;
 598                 /*
 599                  * If trying to read past EOF, make sure the i_size
 600                  * attribute is up-to-date.
 601                  */
 602                 err = fuse_update_attributes(inode, NULL, iocb->ki_filp, NULL);
 603                 if (err)
 604                         return err;
 605         }
 606
 607         return generic_file_aio_read(iocb, iov, nr_segs, pos);
 608 }
 609
 610 static void fuse_write_fill(struct fuse_req *req, struct file *file,
 611                             struct fuse_file *ff, struct inode *inode,
 612                             loff_t pos, size_t count, int writepage)
 613 {
 614         struct fuse_conn *fc = get_fuse_conn(inode);
 615         struct fuse_write_in *inarg = &req->misc.write.in;
 616         struct fuse_write_out *outarg = &req->misc.write.out;
 617
 618         memset(inarg, 0, sizeof(struct fuse_write_in));
 619         inarg->fh = ff->fh;
 620         inarg->offset = pos;
 621         inarg->size = count;
 622         inarg->write_flags = writepage ? FUSE_WRITE_CACHE : 0;
 623         inarg->flags = file ? file->f_flags : 0;
 624         req->in.h.opcode = FUSE_WRITE;
 625         req->in.h.nodeid = get_node_id(inode);
 626         req->in.numargs = 2;
 627         if (fc->minor < 9)
 628                 req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
 629         else
 630                 req->in.args[0].size = sizeof(struct fuse_write_in);
 631         req->in.args[0].value = inarg;
 632         req->in.args[1].size = count;
 633         req->out.numargs = 1;
 634         req->out.args[0].size = sizeof(struct fuse_write_out);
 635         req->out.args[0].value = outarg;
 636 }
 637
 638 static size_t fuse_send_write(struct fuse_req *req, struct file *file,
 639                               struct inode *inode, loff_t pos, size_t count,
 640                               fl_owner_t owner)
 641 {
 642         struct fuse_conn *fc = get_fuse_conn(inode);
 643         fuse_write_fill(req, file, file->private_data, inode, pos, count, 0);
 644         if (owner != NULL) {
 645                 struct fuse_write_in *inarg = &req->misc.write.in;
 646                 inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
 647                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 648         }
 649         fuse_request_send(fc, req);
 650         return req->misc.write.out.size;
 651 }
 652
 653 static int fuse_write_begin(struct file *file, struct address_space *mapping,
 654                         loff_t pos, unsigned len, unsigned flags,
 655                         struct page **pagep, void **fsdata)
 656 {
 657         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 658
 659         *pagep = grab_cache_page_write_begin(mapping, index, flags);
 660         if (!*pagep)
 661                 return -ENOMEM;
 662         return 0;
 663 }
 664
 665 static void fuse_write_update_size(struct inode *inode, loff_t pos)
 666 {
 667         struct fuse_conn *fc = get_fuse_conn(inode);
 668         struct fuse_inode *fi = get_fuse_inode(inode);
 669
 670         spin_lock(&fc->lock);
 671         fi->attr_version = ++fc->attr_version;
 672         if (pos > inode->i_size)
 673                 i_size_write(inode, pos);
 674         spin_unlock(&fc->lock);
 675 }
 676
 677 static int fuse_buffered_write(struct file *file, struct inode *inode,
 678                                loff_t pos, unsigned count, struct page *page)
 679 {
 680         int err;
 681         size_t nres;
 682         struct fuse_conn *fc = get_fuse_conn(inode);
 683         unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
 684         struct fuse_req *req;
 685
 686         if (is_bad_inode(inode))
 687                 return -EIO;
 688
 689         /*
 690          * Make sure writepages on the same page are not mixed up with
 691          * plain writes.
 692          */
 693         fuse_wait_on_page_writeback(inode, page->index);
 694
 695         req = fuse_get_req(fc);
 696         if (IS_ERR(req))
 697                 return PTR_ERR(req);
 698
 699         req->in.argpages = 1;
 700         req->num_pages = 1;
 701         req->pages[0] = page;
 702         req->page_offset = offset;
 703         nres = fuse_send_write(req, file, inode, pos, count, NULL);
 704         err = req->out.h.error;
 705         fuse_put_request(fc, req);
 706         if (!err && !nres)
 707                 err = -EIO;
 708         if (!err) {
 709                 pos += nres;
 710                 fuse_write_update_size(inode, pos);
 711                 if (count == PAGE_CACHE_SIZE)
 712                         SetPageUptodate(page);
 713         }
 714         fuse_invalidate_attr(inode);
 715         return err ? err : nres;
 716 }
 717
 718 static int fuse_write_end(struct file *file, struct address_space *mapping,
 719                         loff_t pos, unsigned len, unsigned copied,
 720                         struct page *page, void *fsdata)
 721 {
 722         struct inode *inode = mapping->host;
 723         int res = 0;
 724
 725         if (copied)
 726                 res = fuse_buffered_write(file, inode, pos, copied, page);
 727
 728         unlock_page(page);
 729         page_cache_release(page);
 730         return res;
 731 }
 732
 733 static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
 734                                     struct inode *inode, loff_t pos,
 735                                     size_t count)
 736 {
 737         size_t res;
 738         unsigned offset;
 739         unsigned i;
 740
 741         for (i = 0; i < req->num_pages; i++)
 742                 fuse_wait_on_page_writeback(inode, req->pages[i]->index);
 743
 744         res = fuse_send_write(req, file, inode, pos, count, NULL);
 745
 746         offset = req->page_offset;
 747         count = res;
 748         for (i = 0; i < req->num_pages; i++) {
 749                 struct page *page = req->pages[i];
 750
 751                 if (!req->out.h.error && !offset && count >= PAGE_CACHE_SIZE)
 752                         SetPageUptodate(page);
 753
 754                 if (count > PAGE_CACHE_SIZE - offset)
 755                         count -= PAGE_CACHE_SIZE - offset;
 756                 else
 757                         count = 0;
 758                 offset = 0;
 759
 760                 unlock_page(page);
 761                 page_cache_release(page);
 762         }
 763
 764         return res;
 765 }
 766
 767 static ssize_t fuse_fill_write_pages(struct fuse_req *req,
 768                                struct address_space *mapping,
 769                                struct iov_iter *ii, loff_t pos)
 770 {
 771         struct fuse_conn *fc = get_fuse_conn(mapping->host);
 772         unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
 773         size_t count = 0;
 774         int err;
 775
 776         req->in.argpages = 1;
 777         req->page_offset = offset;
 778
 779         do {
 780                 size_t tmp;
 781                 struct page *page;
 782                 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 783                 size_t bytes = min_t(size_t, PAGE_CACHE_SIZE - offset,
 784                                      iov_iter_count(ii));
 785
 786                 bytes = min_t(size_t, bytes, fc->max_write - count);
 787
 788  again:
 789                 err = -EFAULT;
 790                 if (iov_iter_fault_in_readable(ii, bytes))
 791                         break;
 792
 793                 err = -ENOMEM;
 794                 page = grab_cache_page_write_begin(mapping, index, 0);
 795                 if (!page)
 796                         break;
 797
 798                 pagefault_disable();
 799                 tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
 800                 pagefault_enable();
 801                 flush_dcache_page(page);
 802
 803                 if (!tmp) {
 804                         unlock_page(page);
 805                         page_cache_release(page);
 806                         bytes = min(bytes, iov_iter_single_seg_count(ii));
 807                         goto again;
 808                 }
 809
 810                 err = 0;
 811                 req->pages[req->num_pages] = page;
 812                 req->num_pages++;
 813
 814                 iov_iter_advance(ii, tmp);
 815                 count += tmp;
 816                 pos += tmp;
 817                 offset += tmp;
 818                 if (offset == PAGE_CACHE_SIZE)
 819                         offset = 0;
 820
 821                 if (!fc->big_writes)
 822                         break;
 823         } while (iov_iter_count(ii) && count < fc->max_write &&
 824                  req->num_pages < FUSE_MAX_PAGES_PER_REQ && offset == 0);
 825
 826         return count > 0 ? count : err;
 827 }
 828
 829 static ssize_t fuse_perform_write(struct file *file,
 830                                   struct address_space *mapping,
 831                                   struct iov_iter *ii, loff_t pos)
 832 {
 833         struct inode *inode = mapping->host;
 834         struct fuse_conn *fc = get_fuse_conn(inode);
 835         int err = 0;
 836         ssize_t res = 0;
 837
 838         if (is_bad_inode(inode))
 839                 return -EIO;
 840
 841         do {
 842                 struct fuse_req *req;
 843                 ssize_t count;
 844
 845                 req = fuse_get_req(fc);
 846                 if (IS_ERR(req)) {
 847                         err = PTR_ERR(req);
 848                         break;
 849                 }
 850
 851                 count = fuse_fill_write_pages(req, mapping, ii, pos);
 852                 if (count <= 0) {
 853                         err = count;
 854                 } else {
 855                         size_t num_written;
 856
 857                         num_written = fuse_send_write_pages(req, file, inode,
 858                                                             pos, count);
 859                         err = req->out.h.error;
 860                         if (!err) {
 861                                 res += num_written;
 862                                 pos += num_written;
 863
 864                                 /* break out of the loop on short write */
 865                                 if (num_written != count)
 866                                         err = -EIO;
 867                         }
 868                 }
 869                 fuse_put_request(fc, req);
 870         } while (!err && iov_iter_count(ii));
 871
 872         if (res > 0)
 873                 fuse_write_update_size(inode, pos);
 874
 875         fuse_invalidate_attr(inode);
 876
 877         return res > 0 ? res : err;
 878 }
 879
 880 static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 881                                    unsigned long nr_segs, loff_t pos)
 882 {
 883         struct file *file = iocb->ki_filp;
 884         struct address_space *mapping = file->f_mapping;
 885         size_t count = 0;
 886         ssize_t written = 0;
 887         struct inode *inode = mapping->host;
 888         ssize_t err;
 889         struct iov_iter i;
 890
 891         WARN_ON(iocb->ki_pos != pos);
 892
 893         err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
 894         if (err)
 895                 return err;
 896
 897         mutex_lock(&inode->i_mutex);
 898         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 899
 900         /* We can write back this queue in page reclaim */
 901         current->backing_dev_info = mapping->backing_dev_info;
 902
 903         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 904         if (err)
 905                 goto out;
 906
 907         if (count == 0)
 908                 goto out;
 909
 910         err = file_remove_suid(file);
 911         if (err)
 912                 goto out;
 913
 914         file_update_time(file);
 915
 916         iov_iter_init(&i, iov, nr_segs, count, 0);
 917         written = fuse_perform_write(file, mapping, &i, pos);
 918         if (written >= 0)
 919                 iocb->ki_pos = pos + written;
 920
 921 out:
 922         current->backing_dev_info = NULL;
 923         mutex_unlock(&inode->i_mutex);
 924
 925         return written ? written : err;
 926 }
 927
 928 static void fuse_release_user_pages(struct fuse_req *req, int write)
 929 {
 930         unsigned i;
 931
 932         for (i = 0; i < req->num_pages; i++) {
 933                 struct page *page = req->pages[i];
 934                 if (write)
 935                         set_page_dirty_lock(page);
 936                 put_page(page);
 937         }
 938 }
 939
 940 static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
 941                                unsigned *nbytesp, int write)
 942 {
 943         unsigned nbytes = *nbytesp;
 944         unsigned long user_addr = (unsigned long) buf;
 945         unsigned offset = user_addr & ~PAGE_MASK;
 946         int npages;
 947
 948         /* Special case for kernel I/O: can copy directly into the buffer */
 949         if (segment_eq(get_fs(), KERNEL_DS)) {
 950                 if (write)
 951                         req->in.args[1].value = (void *) user_addr;
 952                 else
 953                         req->out.args[0].value = (void *) user_addr;
 954
 955                 return 0;
 956         }
 957
 958         nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
 959         npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
 960         npages = clamp(npages, 1, FUSE_MAX_PAGES_PER_REQ);
 961         down_read(&current->mm->mmap_sem);
 962         npages = get_user_pages(current, current->mm, user_addr, npages, !write,
 963                                 0, req->pages, NULL);
 964         up_read(&current->mm->mmap_sem);
 965         if (npages < 0)
 966                 return npages;
 967
 968         req->num_pages = npages;
 969         req->page_offset = offset;
 970
 971         if (write)
 972                 req->in.argpages = 1;
 973         else
 974                 req->out.argpages = 1;
 975
 976         nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
 977         *nbytesp = min(*nbytesp, nbytes);
 978
 979         return 0;
 980 }
 981
 982 static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 983                               size_t count, loff_t *ppos, int write)
 984 {
 985         struct inode *inode = file->f_path.dentry->d_inode;
 986         struct fuse_conn *fc = get_fuse_conn(inode);
 987         size_t nmax = write ? fc->max_write : fc->max_read;
 988         loff_t pos = *ppos;
 989         ssize_t res = 0;
 990         struct fuse_req *req;
 991
 992         if (is_bad_inode(inode))
 993                 return -EIO;
 994
 995         req = fuse_get_req(fc);
 996         if (IS_ERR(req))
 997                 return PTR_ERR(req);
 998
 999         while (count) {
1000                 size_t nres;
1001                 size_t nbytes = min(count, nmax);
1002                 int err = fuse_get_user_pages(req, buf, &nbytes, write);
1003                 if (err) {
1004                         res = err;
1005                         break;
1006                 }
1007
1008                 if (write)
1009                         nres = fuse_send_write(req, file, inode, pos, nbytes,
1010                                                current->files);
1011                 else
1012                         nres = fuse_send_read(req, file, inode, pos, nbytes,
1013                                               current->files);
1014                 fuse_release_user_pages(req, !write);
1015                 if (req->out.h.error) {
1016                         if (!res)
1017                                 res = req->out.h.error;
1018                         break;
1019                 } else if (nres > nbytes) {
1020                         res = -EIO;
1021                         break;
1022                 }
1023                 count -= nres;
1024                 res += nres;
1025                 pos += nres;
1026                 buf += nres;
1027                 if (nres != nbytes)
1028                         break;
1029                 if (count) {
1030                         fuse_put_request(fc, req);
1031                         req = fuse_get_req(fc);
1032                         if (IS_ERR(req))
1033                                 break;
1034                 }
1035         }
1036         fuse_put_request(fc, req);
1037         if (res > 0) {
1038                 if (write)
1039                         fuse_write_update_size(inode, pos);
1040                 *ppos = pos;
1041         }
1042         fuse_invalidate_attr(inode);
1043
1044         return res;
1045 }
1046
1047 static ssize_t fuse_direct_read(struct file *file, char __user *buf,
1048                                      size_t count, loff_t *ppos)
1049 {
1050         return fuse_direct_io(file, buf, count, ppos, 0);
1051 }
1052
1053 static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
1054                                  size_t count, loff_t *ppos)
1055 {
1056         struct inode *inode = file->f_path.dentry->d_inode;
1057         ssize_t res;
1058         /* Don't allow parallel writes to the same file */
1059         mutex_lock(&inode->i_mutex);
1060         res = generic_write_checks(file, ppos, &count, 0);
1061         if (!res)
1062                 res = fuse_direct_io(file, buf, count, ppos, 1);
1063         mutex_unlock(&inode->i_mutex);
1064         return res;
1065 }
1066
1067 static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
1068 {
1069         __free_page(req->pages[0]);
1070         fuse_file_put(req->ff);
1071 }
1072
1073 static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
1074 {
1075         struct inode *inode = req->inode;
1076         struct fuse_inode *fi = get_fuse_inode(inode);
1077         struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
1078
1079         list_del(&req->writepages_entry);
1080         dec_bdi_stat(bdi, BDI_WRITEBACK);
1081         dec_zone_page_state(req->pages[0], NR_WRITEBACK_TEMP);
1082         bdi_writeout_inc(bdi);
1083         wake_up(&fi->page_waitq);
1084 }
1085
1086 /* Called under fc->lock, may release and reacquire it */
1087 static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req)
1088 __releases(&fc->lock)
1089 __acquires(&fc->lock)
1090 {
1091         struct fuse_inode *fi = get_fuse_inode(req->inode);
1092         loff_t size = i_size_read(req->inode);
1093         struct fuse_write_in *inarg = &req->misc.write.in;
1094
1095         if (!fc->connected)
1096                 goto out_free;
1097
1098         if (inarg->offset + PAGE_CACHE_SIZE <= size) {
1099                 inarg->size = PAGE_CACHE_SIZE;
1100         } else if (inarg->offset < size) {
1101                 inarg->size = size & (PAGE_CACHE_SIZE - 1);
1102         } else {
1103                 /* Got truncated off completely */
1104                 goto out_free;
1105         }
1106
1107         req->in.args[1].size = inarg->size;
1108         fi->writectr++;
1109         fuse_request_send_background_locked(fc, req);
1110         return;
1111
1112  out_free:
1113         fuse_writepage_finish(fc, req);
1114         spin_unlock(&fc->lock);
1115         fuse_writepage_free(fc, req);
1116         fuse_put_request(fc, req);
1117         spin_lock(&fc->lock);
1118 }
1119
1120 /*
1121  * If fi->writectr is positive (no truncate or fsync going on) send
1122  * all queued writepage requests.
1123  *
1124  * Called with fc->lock
1125  */
1126 void fuse_flush_writepages(struct inode *inode)
1127 __releases(&fc->lock)
1128 __acquires(&fc->lock)
1129 {
1130         struct fuse_conn *fc = get_fuse_conn(inode);
1131         struct fuse_inode *fi = get_fuse_inode(inode);
1132         struct fuse_req *req;
1133
1134         while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
1135                 req = list_entry(fi->queued_writes.next, struct fuse_req, list);
1136                 list_del_init(&req->list);
1137                 fuse_send_writepage(fc, req);
1138         }
1139 }
1140
1141 static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
1142 {
1143         struct inode *inode = req->inode;
1144         struct fuse_inode *fi = get_fuse_inode(inode);
1145
1146         mapping_set_error(inode->i_mapping, req->out.h.error);
1147         spin_lock(&fc->lock);
1148         fi->writectr--;
1149         fuse_writepage_finish(fc, req);
1150         spin_unlock(&fc->lock);
1151         fuse_writepage_free(fc, req);
1152 }
1153
1154 static int fuse_writepage_locked(struct page *page)
1155 {
1156         struct address_space *mapping = page->mapping;
1157         struct inode *inode = mapping->host;
1158         struct fuse_conn *fc = get_fuse_conn(inode);
1159         struct fuse_inode *fi = get_fuse_inode(inode);
1160         struct fuse_req *req;
1161         struct fuse_file *ff;
1162         struct page *tmp_page;
1163
1164         set_page_writeback(page);
1165
1166         req = fuse_request_alloc_nofs();
1167         if (!req)
1168                 goto err;
1169
1170         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1171         if (!tmp_page)
1172                 goto err_free;
1173
1174         spin_lock(&fc->lock);
1175         BUG_ON(list_empty(&fi->write_files));
1176         ff = list_entry(fi->write_files.next, struct fuse_file, write_entry);
1177         req->ff = fuse_file_get(ff);
1178         spin_unlock(&fc->lock);
1179
1180         fuse_write_fill(req, NULL, ff, inode, page_offset(page), 0, 1);
1181
1182         copy_highpage(tmp_page, page);
1183         req->in.argpages = 1;
1184         req->num_pages = 1;
1185         req->pages[0] = tmp_page;
1186         req->page_offset = 0;
1187         req->end = fuse_writepage_end;
1188         req->inode = inode;
1189
1190         inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK);
1191         inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
1192         end_page_writeback(page);
1193
1194         spin_lock(&fc->lock);
1195         list_add(&req->writepages_entry, &fi->writepages);
1196         list_add_tail(&req->list, &fi->queued_writes);
1197         fuse_flush_writepages(inode);
1198         spin_unlock(&fc->lock);
1199
1200         return 0;
1201
1202 err_free:
1203         fuse_request_free(req);
1204 err:
1205         end_page_writeback(page);
1206         return -ENOMEM;
1207 }
1208
1209 static int fuse_writepage(struct page *page, struct writeback_control *wbc)
1210 {
1211         int err;
1212
1213         err = fuse_writepage_locked(page);
1214         unlock_page(page);
1215
1216         return err;
1217 }
1218
1219 static int fuse_launder_page(struct page *page)
1220 {
1221         int err = 0;
1222         if (clear_page_dirty_for_io(page)) {
1223                 struct inode *inode = page->mapping->host;
1224                 err = fuse_writepage_locked(page);
1225                 if (!err)
1226                         fuse_wait_on_page_writeback(inode, page->index);
1227         }
1228         return err;
1229 }
1230
1231 /*
1232  * Write back dirty pages now, because there may not be any suitable
1233  * open files later
1234  */
1235 static void fuse_vma_close(struct vm_area_struct *vma)
1236 {
1237         filemap_write_and_wait(vma->vm_file->f_mapping);
1238 }
1239
1240 /*
1241  * Wait for writeback against this page to complete before allowing it
1242  * to be marked dirty again, and hence written back again, possibly
1243  * before the previous writepage completed.
1244  *
1245  * Block here, instead of in ->writepage(), so that the userspace fs
1246  * can only block processes actually operating on the filesystem.
1247  *
1248  * Otherwise unprivileged userspace fs would be able to block
1249  * unrelated:
1250  *
1251  * - page migration
1252  * - sync(2)
1253  * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
1254  */
1255 static int fuse_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
1256 {
1257         struct page *page = vmf->page;
1258         /*
1259          * Don't use page->mapping as it may become NULL from a
1260          * concurrent truncate.
1261          */
1262         struct inode *inode = vma->vm_file->f_mapping->host;
1263
1264         fuse_wait_on_page_writeback(inode, page->index);
1265         return 0;
1266 }
1267
1268 static struct vm_operations_struct fuse_file_vm_ops = {
1269         .close          = fuse_vma_close,
1270         .fault          = filemap_fault,
1271         .page_mkwrite   = fuse_page_mkwrite,
1272 };
1273
1274 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
1275 {
1276         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) {
1277                 struct inode *inode = file->f_dentry->d_inode;
1278                 struct fuse_conn *fc = get_fuse_conn(inode);
1279                 struct fuse_inode *fi = get_fuse_inode(inode);
1280                 struct fuse_file *ff = file->private_data;
1281                 /*
1282                  * file may be written through mmap, so chain it onto the
1283                  * inodes's write_file list
1284                  */
1285                 spin_lock(&fc->lock);
1286                 if (list_empty(&ff->write_entry))
1287                         list_add(&ff->write_entry, &fi->write_files);
1288                 spin_unlock(&fc->lock);
1289         }
1290         file_accessed(file);
1291         vma->vm_ops = &fuse_file_vm_ops;
1292         return 0;
1293 }
1294
1295 static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
1296                                   struct file_lock *fl)
1297 {
1298         switch (ffl->type) {
1299         case F_UNLCK:
1300                 break;
1301
1302         case F_RDLCK:
1303         case F_WRLCK:
1304                 if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
1305                     ffl->end < ffl->start)
1306                         return -EIO;
1307
1308                 fl->fl_start = ffl->start;
1309                 fl->fl_end = ffl->end;
1310                 fl->fl_pid = ffl->pid;
1311                 break;
1312
1313         default:
1314                 return -EIO;
1315         }
1316         fl->fl_type = ffl->type;
1317         return 0;
1318 }
1319
1320 static void fuse_lk_fill(struct fuse_req *req, struct file *file,
1321                          const struct file_lock *fl, int opcode, pid_t pid,
1322                          int flock)
1323 {
1324         struct inode *inode = file->f_path.dentry->d_inode;
1325         struct fuse_conn *fc = get_fuse_conn(inode);
1326         struct fuse_file *ff = file->private_data;
1327         struct fuse_lk_in *arg = &req->misc.lk_in;
1328
1329         arg->fh = ff->fh;
1330         arg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
1331         arg->lk.start = fl->fl_start;
1332         arg->lk.end = fl->fl_end;
1333         arg->lk.type = fl->fl_type;
1334         arg->lk.pid = pid;
1335         if (flock)
1336                 arg->lk_flags |= FUSE_LK_FLOCK;
1337         req->in.h.opcode = opcode;
1338         req->in.h.nodeid = get_node_id(inode);
1339         req->in.numargs = 1;
1340         req->in.args[0].size = sizeof(*arg);
1341         req->in.args[0].value = arg;
1342 }
1343
1344 static int fuse_getlk(struct file *file, struct file_lock *fl)
1345 {
1346         struct inode *inode = file->f_path.dentry->d_inode;
1347         struct fuse_conn *fc = get_fuse_conn(inode);
1348         struct fuse_req *req;
1349         struct fuse_lk_out outarg;
1350         int err;
1351
1352         req = fuse_get_req(fc);
1353         if (IS_ERR(req))
1354                 return PTR_ERR(req);
1355
1356         fuse_lk_fill(req, file, fl, FUSE_GETLK, 0, 0);
1357         req->out.numargs = 1;
1358         req->out.args[0].size = sizeof(outarg);
1359         req->out.args[0].value = &outarg;
1360         fuse_request_send(fc, req);
1361         err = req->out.h.error;
1362         fuse_put_request(fc, req);
1363         if (!err)
1364                 err = convert_fuse_file_lock(&outarg.lk, fl);
1365
1366         return err;
1367 }
1368
1369 static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
1370 {
1371         struct inode *inode = file->f_path.dentry->d_inode;
1372         struct fuse_conn *fc = get_fuse_conn(inode);
1373         struct fuse_req *req;
1374         int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
1375         pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
1376         int err;
1377
1378         if (fl->fl_lmops && fl->fl_lmops->fl_grant) {
1379                 /* NLM needs asynchronous locks, which we don't support yet */
1380                 return -ENOLCK;
1381         }
1382
1383         /* Unlock on close is handled by the flush method */
1384         if (fl->fl_flags & FL_CLOSE)
1385                 return 0;
1386
1387         req = fuse_get_req(fc);
1388         if (IS_ERR(req))
1389                 return PTR_ERR(req);
1390
1391         fuse_lk_fill(req, file, fl, opcode, pid, flock);
1392         fuse_request_send(fc, req);
1393         err = req->out.h.error;
1394         /* locking is restartable */
1395         if (err == -EINTR)
1396                 err = -ERESTARTSYS;
1397         fuse_put_request(fc, req);
1398         return err;
1399 }
1400
1401 static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
1402 {
1403         struct inode *inode = file->f_path.dentry->d_inode;
1404         struct fuse_conn *fc = get_fuse_conn(inode);
1405         int err;
1406
1407         if (cmd == F_CANCELLK) {
1408                 err = 0;
1409         } else if (cmd == F_GETLK) {
1410                 if (fc->no_lock) {
1411                         posix_test_lock(file, fl);
1412                         err = 0;
1413                 } else
1414                         err = fuse_getlk(file, fl);
1415         } else {
1416                 if (fc->no_lock)
1417                         err = posix_lock_file(file, fl, NULL);
1418                 else
1419                         err = fuse_setlk(file, fl, 0);
1420         }
1421         return err;
1422 }
1423
1424 static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
1425 {
1426         struct inode *inode = file->f_path.dentry->d_inode;
1427         struct fuse_conn *fc = get_fuse_conn(inode);
1428         int err;
1429
1430         if (fc->no_lock) {
1431                 err = flock_lock_file_wait(file, fl);
1432         } else {
1433                 /* emulate flock with POSIX locks */
1434                 fl->fl_owner = (fl_owner_t) file;
1435                 err = fuse_setlk(file, fl, 1);
1436         }
1437
1438         return err;
1439 }
1440
1441 static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
1442 {
1443         struct inode *inode = mapping->host;
1444         struct fuse_conn *fc = get_fuse_conn(inode);
1445         struct fuse_req *req;
1446         struct fuse_bmap_in inarg;
1447         struct fuse_bmap_out outarg;
1448         int err;
1449
1450         if (!inode->i_sb->s_bdev || fc->no_bmap)
1451                 return 0;
1452
1453         req = fuse_get_req(fc);
1454         if (IS_ERR(req))
1455                 return 0;
1456
1457         memset(&inarg, 0, sizeof(inarg));
1458         inarg.block = block;
1459         inarg.blocksize = inode->i_sb->s_blocksize;
1460         req->in.h.opcode = FUSE_BMAP;
1461         req->in.h.nodeid = get_node_id(inode);
1462         req->in.numargs = 1;
1463         req->in.args[0].size = sizeof(inarg);
1464         req->in.args[0].value = &inarg;
1465         req->out.numargs = 1;
1466         req->out.args[0].size = sizeof(outarg);
1467         req->out.args[0].value = &outarg;
1468         fuse_request_send(fc, req);
1469         err = req->out.h.error;
1470         fuse_put_request(fc, req);
1471         if (err == -ENOSYS)
1472                 fc->no_bmap = 1;
1473
1474         return err ? 0 : outarg.block;
1475 }
1476
1477 static loff_t fuse_file_llseek(struct file *file, loff_t offset, int origin)
1478 {
1479         loff_t retval;
1480         struct inode *inode = file->f_path.dentry->d_inode;
1481
1482         mutex_lock(&inode->i_mutex);
1483         switch (origin) {
1484         case SEEK_END:
1485                 retval = fuse_update_attributes(inode, NULL, file, NULL);
1486                 if (retval)
1487                         goto exit;
1488                 offset += i_size_read(inode);
1489                 break;
1490         case SEEK_CUR:
1491                 offset += file->f_pos;
1492         }
1493         retval = -EINVAL;
1494         if (offset >= 0 && offset <= inode->i_sb->s_maxbytes) {
1495                 if (offset != file->f_pos) {
1496                         file->f_pos = offset;
1497                         file->f_version = 0;
1498                 }
1499                 retval = offset;
1500         }
1501 exit:
1502         mutex_unlock(&inode->i_mutex);
1503         return retval;
1504 }
1505
1506 static int fuse_ioctl_copy_user(struct page **pages, struct iovec *iov,
1507                         unsigned int nr_segs, size_t bytes, bool to_user)
1508 {
1509         struct iov_iter ii;
1510         int page_idx = 0;
1511
1512         if (!bytes)
1513                 return 0;
1514
1515         iov_iter_init(&ii, iov, nr_segs, bytes, 0);
1516
1517         while (iov_iter_count(&ii)) {
1518                 struct page *page = pages[page_idx++];
1519                 size_t todo = min_t(size_t, PAGE_SIZE, iov_iter_count(&ii));
1520                 void *kaddr, *map;
1521
1522                 kaddr = map = kmap(page);
1523
1524                 while (todo) {
1525                         char __user *uaddr = ii.iov->iov_base + ii.iov_offset;
1526                         size_t iov_len = ii.iov->iov_len - ii.iov_offset;
1527                         size_t copy = min(todo, iov_len);
1528                         size_t left;
1529
1530                         if (!to_user)
1531                                 left = copy_from_user(kaddr, uaddr, copy);
1532                         else
1533                                 left = copy_to_user(uaddr, kaddr, copy);
1534
1535                         if (unlikely(left))
1536                                 return -EFAULT;
1537
1538                         iov_iter_advance(&ii, copy);
1539                         todo -= copy;
1540                         kaddr += copy;
1541                 }
1542
1543                 kunmap(map);
1544         }
1545
1546         return 0;
1547 }
1548
1549 /*
1550  * For ioctls, there is no generic way to determine how much memory
1551  * needs to be read and/or written.  Furthermore, ioctls are allowed
1552  * to dereference the passed pointer, so the parameter requires deep
1553  * copying but FUSE has no idea whatsoever about what to copy in or
1554  * out.
1555  *
1556  * This is solved by allowing FUSE server to retry ioctl with
1557  * necessary in/out iovecs.  Let's assume the ioctl implementation
1558  * needs to read in the following structure.
1559  *
1560  * struct a {
1561  *      char    *buf;
1562  *      size_t  buflen;
1563  * }
1564  *
1565  * On the first callout to FUSE server, inarg->in_size and
1566  * inarg->out_size will be NULL; then, the server completes the ioctl
1567  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
1568  * the actual iov array to
1569  *
1570  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
1571  *
1572  * which tells FUSE to copy in the requested area and retry the ioctl.
1573  * On the second round, the server has access to the structure and
1574  * from that it can tell what to look for next, so on the invocation,
1575  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
1576  *
1577  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
1578  *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
1579  *
1580  * FUSE will copy both struct a and the pointed buffer from the
1581  * process doing the ioctl and retry ioctl with both struct a and the
1582  * buffer.
1583  *
1584  * This time, FUSE server has everything it needs and completes ioctl
1585  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
1586  *
1587  * Copying data out works the same way.
1588  *
1589  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
1590  * automatically initializes in and out iovs by decoding @cmd with
1591  * _IOC_* macros and the server is not allowed to request RETRY.  This
1592  * limits ioctl data transfers to well-formed ioctls and is the forced
1593  * behavior for all FUSE servers.
1594  */
1595 static long fuse_file_do_ioctl(struct file *file, unsigned int cmd,
1596                                unsigned long arg, unsigned int flags)
1597 {
1598         struct inode *inode = file->f_dentry->d_inode;
1599         struct fuse_file *ff = file->private_data;
1600         struct fuse_conn *fc = get_fuse_conn(inode);
1601         struct fuse_ioctl_in inarg = {
1602                 .fh = ff->fh,
1603                 .cmd = cmd,
1604                 .arg = arg,
1605                 .flags = flags
1606         };
1607         struct fuse_ioctl_out outarg;
1608         struct fuse_req *req = NULL;
1609         struct page **pages = NULL;
1610         struct page *iov_page = NULL;
1611         struct iovec *in_iov = NULL, *out_iov = NULL;
1612         unsigned int in_iovs = 0, out_iovs = 0, num_pages = 0, max_pages;
1613         size_t in_size, out_size, transferred;
1614         int err;
1615
1616         /* assume all the iovs returned by client always fits in a page */
1617         BUILD_BUG_ON(sizeof(struct iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
1618
1619         if (!fuse_allow_task(fc, current))
1620                 return -EACCES;
1621
1622         err = -EIO;
1623         if (is_bad_inode(inode))
1624                 goto out;
1625
1626         err = -ENOMEM;
1627         pages = kzalloc(sizeof(pages[0]) * FUSE_MAX_PAGES_PER_REQ, GFP_KERNEL);
1628         iov_page = alloc_page(GFP_KERNEL);
1629         if (!pages || !iov_page)
1630                 goto out;
1631
1632         /*
1633          * If restricted, initialize IO parameters as encoded in @cmd.
1634          * RETRY from server is not allowed.
1635          */
1636         if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
1637                 struct iovec *iov = page_address(iov_page);
1638
1639                 iov->iov_base = (void __user *)arg;
1640                 iov->iov_len = _IOC_SIZE(cmd);
1641
1642                 if (_IOC_DIR(cmd) & _IOC_WRITE) {
1643                         in_iov = iov;
1644                         in_iovs = 1;
1645                 }
1646
1647                 if (_IOC_DIR(cmd) & _IOC_READ) {
1648                         out_iov = iov;
1649                         out_iovs = 1;
1650                 }
1651         }
1652
1653  retry:
1654         inarg.in_size = in_size = iov_length(in_iov, in_iovs);
1655         inarg.out_size = out_size = iov_length(out_iov, out_iovs);
1656
1657         /*
1658          * Out data can be used either for actual out data or iovs,
1659          * make sure there always is at least one page.
1660          */
1661         out_size = max_t(size_t, out_size, PAGE_SIZE);
1662         max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
1663
1664         /* make sure there are enough buffer pages and init request with them */
1665         err = -ENOMEM;
1666         if (max_pages > FUSE_MAX_PAGES_PER_REQ)
1667                 goto out;
1668         while (num_pages < max_pages) {
1669                 pages[num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
1670                 if (!pages[num_pages])
1671                         goto out;
1672                 num_pages++;
1673         }
1674
1675         req = fuse_get_req(fc);
1676         if (IS_ERR(req)) {
1677                 err = PTR_ERR(req);
1678                 req = NULL;
1679                 goto out;
1680         }
1681         memcpy(req->pages, pages, sizeof(req->pages[0]) * num_pages);
1682         req->num_pages = num_pages;
1683
1684         /* okay, let's send it to the client */
1685         req->in.h.opcode = FUSE_IOCTL;
1686         req->in.h.nodeid = get_node_id(inode);
1687         req->in.numargs = 1;
1688         req->in.args[0].size = sizeof(inarg);
1689         req->in.args[0].value = &inarg;
1690         if (in_size) {
1691                 req->in.numargs++;
1692                 req->in.args[1].size = in_size;
1693                 req->in.argpages = 1;
1694
1695                 err = fuse_ioctl_copy_user(pages, in_iov, in_iovs, in_size,
1696                                            false);
1697                 if (err)
1698                         goto out;
1699         }
1700
1701         req->out.numargs = 2;
1702         req->out.args[0].size = sizeof(outarg);
1703         req->out.args[0].value = &outarg;
1704         req->out.args[1].size = out_size;
1705         req->out.argpages = 1;
1706         req->out.argvar = 1;
1707
1708         fuse_request_send(fc, req);
1709         err = req->out.h.error;
1710         transferred = req->out.args[1].size;
1711         fuse_put_request(fc, req);
1712         req = NULL;
1713         if (err)
1714                 goto out;
1715
1716         /* did it ask for retry? */
1717         if (outarg.flags & FUSE_IOCTL_RETRY) {
1718                 char *vaddr;
1719
1720                 /* no retry if in restricted mode */
1721                 err = -EIO;
1722                 if (!(flags & FUSE_IOCTL_UNRESTRICTED))
1723                         goto out;
1724
1725                 in_iovs = outarg.in_iovs;
1726                 out_iovs = outarg.out_iovs;
1727
1728                 /*
1729                  * Make sure things are in boundary, separate checks
1730                  * are to protect against overflow.
1731                  */
1732                 err = -ENOMEM;
1733                 if (in_iovs > FUSE_IOCTL_MAX_IOV ||
1734                     out_iovs > FUSE_IOCTL_MAX_IOV ||
1735                     in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
1736                         goto out;
1737
1738                 err = -EIO;
1739                 if ((in_iovs + out_iovs) * sizeof(struct iovec) != transferred)
1740                         goto out;
1741
1742                 /* okay, copy in iovs and retry */
1743                 vaddr = kmap_atomic(pages[0], KM_USER0);
1744                 memcpy(page_address(iov_page), vaddr, transferred);
1745                 kunmap_atomic(vaddr, KM_USER0);
1746
1747                 in_iov = page_address(iov_page);
1748                 out_iov = in_iov + in_iovs;
1749
1750                 goto retry;
1751         }
1752
1753         err = -EIO;
1754         if (transferred > inarg.out_size)
1755                 goto out;
1756
1757         err = fuse_ioctl_copy_user(pages, out_iov, out_iovs, transferred, true);
1758  out:
1759         if (req)
1760                 fuse_put_request(fc, req);
1761         if (iov_page)
1762                 __free_page(iov_page);
1763         while (num_pages)
1764                 __free_page(pages[--num_pages]);
1765         kfree(pages);
1766
1767         return err ? err : outarg.result;
1768 }
1769
1770 static long fuse_file_ioctl(struct file *file, unsigned int cmd,
1771                             unsigned long arg)
1772 {
1773         return fuse_file_do_ioctl(file, cmd, arg, 0);
1774 }
1775
1776 static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
1777                                    unsigned long arg)
1778 {
1779         return fuse_file_do_ioctl(file, cmd, arg, FUSE_IOCTL_COMPAT);
1780 }
1781
1782 /*
1783  * All files which have been polled are linked to RB tree
1784  * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
1785  * find the matching one.
1786  */
1787 static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
1788                                               struct rb_node **parent_out)
1789 {
1790         struct rb_node **link = &fc->polled_files.rb_node;
1791         struct rb_node *last = NULL;
1792
1793         while (*link) {
1794                 struct fuse_file *ff;
1795
1796                 last = *link;
1797                 ff = rb_entry(last, struct fuse_file, polled_node);
1798
1799                 if (kh < ff->kh)
1800                         link = &last->rb_left;
1801                 else if (kh > ff->kh)
1802                         link = &last->rb_right;
1803                 else
1804                         return link;
1805         }
1806
1807         if (parent_out)
1808                 *parent_out = last;
1809         return link;
1810 }
1811
1812 /*
1813  * The file is about to be polled.  Make sure it's on the polled_files
1814  * RB tree.  Note that files once added to the polled_files tree are
1815  * not removed before the file is released.  This is because a file
1816  * polled once is likely to be polled again.
1817  */
1818 static void fuse_register_polled_file(struct fuse_conn *fc,
1819                                       struct fuse_file *ff)
1820 {
1821         spin_lock(&fc->lock);
1822         if (RB_EMPTY_NODE(&ff->polled_node)) {
1823                 struct rb_node **link, *parent;
1824
1825                 link = fuse_find_polled_node(fc, ff->kh, &parent);
1826                 BUG_ON(*link);
1827                 rb_link_node(&ff->polled_node, parent, link);
1828                 rb_insert_color(&ff->polled_node, &fc->polled_files);
1829         }
1830         spin_unlock(&fc->lock);
1831 }
1832
1833 static unsigned fuse_file_poll(struct file *file, poll_table *wait)
1834 {
1835         struct inode *inode = file->f_dentry->d_inode;
1836         struct fuse_file *ff = file->private_data;
1837         struct fuse_conn *fc = get_fuse_conn(inode);
1838         struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
1839         struct fuse_poll_out outarg;
1840         struct fuse_req *req;
1841         int err;
1842
1843         if (fc->no_poll)
1844                 return DEFAULT_POLLMASK;
1845
1846         poll_wait(file, &ff->poll_wait, wait);
1847
1848         /*
1849          * Ask for notification iff there's someone waiting for it.
1850          * The client may ignore the flag and always notify.
1851          */
1852         if (waitqueue_active(&ff->poll_wait)) {
1853                 inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
1854                 fuse_register_polled_file(fc, ff);
1855         }
1856
1857         req = fuse_get_req(fc);
1858         if (IS_ERR(req))
1859                 return PTR_ERR(req);
1860
1861         req->in.h.opcode = FUSE_POLL;
1862         req->in.h.nodeid = get_node_id(inode);
1863         req->in.numargs = 1;
1864         req->in.args[0].size = sizeof(inarg);
1865         req->in.args[0].value = &inarg;
1866         req->out.numargs = 1;
1867         req->out.args[0].size = sizeof(outarg);
1868         req->out.args[0].value = &outarg;
1869         fuse_request_send(fc, req);
1870         err = req->out.h.error;
1871         fuse_put_request(fc, req);
1872
1873         if (!err)
1874                 return outarg.revents;
1875         if (err == -ENOSYS) {
1876                 fc->no_poll = 1;
1877                 return DEFAULT_POLLMASK;
1878         }
1879         return POLLERR;
1880 }
1881
1882 /*
1883  * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
1884  * wakes up the poll waiters.
1885  */
1886 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
1887                             struct fuse_notify_poll_wakeup_out *outarg)
1888 {
1889         u64 kh = outarg->kh;
1890         struct rb_node **link;
1891
1892         spin_lock(&fc->lock);
1893
1894         link = fuse_find_polled_node(fc, kh, NULL);
1895         if (*link) {
1896                 struct fuse_file *ff;
1897
1898                 ff = rb_entry(*link, struct fuse_file, polled_node);
1899                 wake_up_interruptible_sync(&ff->poll_wait);
1900         }
1901
1902         spin_unlock(&fc->lock);
1903         return 0;
1904 }
1905
1906 static const struct file_operations fuse_file_operations = {
1907         .llseek         = fuse_file_llseek,
1908         .read           = do_sync_read,
1909         .aio_read       = fuse_file_aio_read,
1910         .write          = do_sync_write,
1911         .aio_write      = fuse_file_aio_write,
1912         .mmap           = fuse_file_mmap,
1913         .open           = fuse_open,
1914         .flush          = fuse_flush,
1915         .release        = fuse_release,
1916         .fsync          = fuse_fsync,
1917         .lock           = fuse_file_lock,
1918         .flock          = fuse_file_flock,
1919         .splice_read    = generic_file_splice_read,
1920         .unlocked_ioctl = fuse_file_ioctl,
1921         .compat_ioctl   = fuse_file_compat_ioctl,
1922         .poll           = fuse_file_poll,
1923 };
1924
1925 static const struct file_operations fuse_direct_io_file_operations = {
1926         .llseek         = fuse_file_llseek,
1927         .read           = fuse_direct_read,
1928         .write          = fuse_direct_write,
1929         .open           = fuse_open,
1930         .flush          = fuse_flush,
1931         .release        = fuse_release,
1932         .fsync          = fuse_fsync,
1933         .lock           = fuse_file_lock,
1934         .flock          = fuse_file_flock,
1935         .unlocked_ioctl = fuse_file_ioctl,
1936         .compat_ioctl   = fuse_file_compat_ioctl,
1937         .poll           = fuse_file_poll,
1938         /* no mmap and splice_read */
1939 };
1940
1941 static const struct address_space_operations fuse_file_aops  = {
1942         .readpage       = fuse_readpage,
1943         .writepage      = fuse_writepage,
1944         .launder_page   = fuse_launder_page,
1945         .write_begin    = fuse_write_begin,
1946         .write_end      = fuse_write_end,
1947         .readpages      = fuse_readpages,
1948         .set_page_dirty = __set_page_dirty_nobuffers,
1949         .bmap           = fuse_bmap,
1950 };
1951
1952 void fuse_init_file_inode(struct inode *inode)
1953 {
1954         inode->i_fop = &fuse_file_operations;
1955         inode->i_data.a_ops = &fuse_file_aops;
1956 }