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                         ff = 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.argpages = 1;
 390         req->out.argvar = 1;
 391         req->out.numargs = 1;
 392         req->out.args[0].size = count;
 393 }
 394
 395 static size_t fuse_send_read(struct fuse_req *req, struct file *file,
 396                              struct inode *inode, loff_t pos, size_t count,
 397                              fl_owner_t owner)
 398 {
 399         struct fuse_conn *fc = get_fuse_conn(inode);
 400
 401         fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
 402         if (owner != NULL) {
 403                 struct fuse_read_in *inarg = &req->misc.read.in;
 404
 405                 inarg->read_flags |= FUSE_READ_LOCKOWNER;
 406                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 407         }
 408         fuse_request_send(fc, req);
 409         return req->out.args[0].size;
 410 }
 411
 412 static void fuse_read_update_size(struct inode *inode, loff_t size,
 413                                   u64 attr_ver)
 414 {
 415         struct fuse_conn *fc = get_fuse_conn(inode);
 416         struct fuse_inode *fi = get_fuse_inode(inode);
 417
 418         spin_lock(&fc->lock);
 419         if (attr_ver == fi->attr_version && size < inode->i_size) {
 420                 fi->attr_version = ++fc->attr_version;
 421                 i_size_write(inode, size);
 422         }
 423         spin_unlock(&fc->lock);
 424 }
 425
 426 static int fuse_readpage(struct file *file, struct page *page)
 427 {
 428         struct inode *inode = page->mapping->host;
 429         struct fuse_conn *fc = get_fuse_conn(inode);
 430         struct fuse_req *req;
 431         size_t num_read;
 432         loff_t pos = page_offset(page);
 433         size_t count = PAGE_CACHE_SIZE;
 434         u64 attr_ver;
 435         int err;
 436
 437         err = -EIO;
 438         if (is_bad_inode(inode))
 439                 goto out;
 440
 441         /*
 442          * Page writeback can extend beyond the liftime of the
 443          * page-cache page, so make sure we read a properly synced
 444          * page.
 445          */
 446         fuse_wait_on_page_writeback(inode, page->index);
 447
 448         req = fuse_get_req(fc);
 449         err = PTR_ERR(req);
 450         if (IS_ERR(req))
 451                 goto out;
 452
 453         attr_ver = fuse_get_attr_version(fc);
 454
 455         req->out.page_zeroing = 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         req->out.page_zeroing = 1;
 514         fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
 515         req->misc.read.attr_ver = fuse_get_attr_version(fc);
 516         if (fc->async_read) {
 517                 struct fuse_file *ff = file->private_data;
 518                 req->ff = fuse_file_get(ff);
 519                 req->end = fuse_readpages_end;
 520                 fuse_request_send_background(fc, req);
 521         } else {
 522                 fuse_request_send(fc, req);
 523                 fuse_readpages_end(fc, req);
 524                 fuse_put_request(fc, req);
 525         }
 526 }
 527
 528 struct fuse_fill_data {
 529         struct fuse_req *req;
 530         struct file *file;
 531         struct inode *inode;
 532 };
 533
 534 static int fuse_readpages_fill(void *_data, struct page *page)
 535 {
 536         struct fuse_fill_data *data = _data;
 537         struct fuse_req *req = data->req;
 538         struct inode *inode = data->inode;
 539         struct fuse_conn *fc = get_fuse_conn(inode);
 540
 541         fuse_wait_on_page_writeback(inode, page->index);
 542
 543         if (req->num_pages &&
 544             (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 545              (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
 546              req->pages[req->num_pages - 1]->index + 1 != page->index)) {
 547                 fuse_send_readpages(req, data->file, inode);
 548                 data->req = req = fuse_get_req(fc);
 549                 if (IS_ERR(req)) {
 550                         unlock_page(page);
 551                         return PTR_ERR(req);
 552                 }
 553         }
 554         req->pages[req->num_pages] = page;
 555         req->num_pages++;
 556         return 0;
 557 }
 558
 559 static int fuse_readpages(struct file *file, struct address_space *mapping,
 560                           struct list_head *pages, unsigned nr_pages)
 561 {
 562         struct inode *inode = mapping->host;
 563         struct fuse_conn *fc = get_fuse_conn(inode);
 564         struct fuse_fill_data data;
 565         int err;
 566
 567         err = -EIO;
 568         if (is_bad_inode(inode))
 569                 goto out;
 570
 571         data.file = file;
 572         data.inode = inode;
 573         data.req = fuse_get_req(fc);
 574         err = PTR_ERR(data.req);
 575         if (IS_ERR(data.req))
 576                 goto out;
 577
 578         err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
 579         if (!err) {
 580                 if (data.req->num_pages)
 581                         fuse_send_readpages(data.req, file, inode);
 582                 else
 583                         fuse_put_request(fc, data.req);
 584         }
 585 out:
 586         return err;
 587 }
 588
 589 static ssize_t fuse_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 590                                   unsigned long nr_segs, loff_t pos)
 591 {
 592         struct inode *inode = iocb->ki_filp->f_mapping->host;
 593
 594         if (pos + iov_length(iov, nr_segs) > i_size_read(inode)) {
 595                 int err;
 596                 /*
 597                  * If trying to read past EOF, make sure the i_size
 598                  * attribute is up-to-date.
 599                  */
 600                 err = fuse_update_attributes(inode, NULL, iocb->ki_filp, NULL);
 601                 if (err)
 602                         return err;
 603         }
 604
 605         return generic_file_aio_read(iocb, iov, nr_segs, pos);
 606 }
 607
 608 static void fuse_write_fill(struct fuse_req *req, struct file *file,
 609                             struct fuse_file *ff, struct inode *inode,
 610                             loff_t pos, size_t count, int writepage)
 611 {
 612         struct fuse_conn *fc = get_fuse_conn(inode);
 613         struct fuse_write_in *inarg = &req->misc.write.in;
 614         struct fuse_write_out *outarg = &req->misc.write.out;
 615
 616         memset(inarg, 0, sizeof(struct fuse_write_in));
 617         inarg->fh = ff->fh;
 618         inarg->offset = pos;
 619         inarg->size = count;
 620         inarg->write_flags = writepage ? FUSE_WRITE_CACHE : 0;
 621         inarg->flags = file ? file->f_flags : 0;
 622         req->in.h.opcode = FUSE_WRITE;
 623         req->in.h.nodeid = get_node_id(inode);
 624         req->in.argpages = 1;
 625         req->in.numargs = 2;
 626         if (fc->minor < 9)
 627                 req->in.args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
 628         else
 629                 req->in.args[0].size = sizeof(struct fuse_write_in);
 630         req->in.args[0].value = inarg;
 631         req->in.args[1].size = count;
 632         req->out.numargs = 1;
 633         req->out.args[0].size = sizeof(struct fuse_write_out);
 634         req->out.args[0].value = outarg;
 635 }
 636
 637 static size_t fuse_send_write(struct fuse_req *req, struct file *file,
 638                               struct inode *inode, loff_t pos, size_t count,
 639                               fl_owner_t owner)
 640 {
 641         struct fuse_conn *fc = get_fuse_conn(inode);
 642         fuse_write_fill(req, file, file->private_data, inode, pos, count, 0);
 643         if (owner != NULL) {
 644                 struct fuse_write_in *inarg = &req->misc.write.in;
 645                 inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
 646                 inarg->lock_owner = fuse_lock_owner_id(fc, owner);
 647         }
 648         fuse_request_send(fc, req);
 649         return req->misc.write.out.size;
 650 }
 651
 652 static int fuse_write_begin(struct file *file, struct address_space *mapping,
 653                         loff_t pos, unsigned len, unsigned flags,
 654                         struct page **pagep, void **fsdata)
 655 {
 656         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 657
 658         *pagep = __grab_cache_page(mapping, index);
 659         if (!*pagep)
 660                 return -ENOMEM;
 661         return 0;
 662 }
 663
 664 static void fuse_write_update_size(struct inode *inode, loff_t pos)
 665 {
 666         struct fuse_conn *fc = get_fuse_conn(inode);
 667         struct fuse_inode *fi = get_fuse_inode(inode);
 668
 669         spin_lock(&fc->lock);
 670         fi->attr_version = ++fc->attr_version;
 671         if (pos > inode->i_size)
 672                 i_size_write(inode, pos);
 673         spin_unlock(&fc->lock);
 674 }
 675
 676 static int fuse_buffered_write(struct file *file, struct inode *inode,
 677                                loff_t pos, unsigned count, struct page *page)
 678 {
 679         int err;
 680         size_t nres;
 681         struct fuse_conn *fc = get_fuse_conn(inode);
 682         unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
 683         struct fuse_req *req;
 684
 685         if (is_bad_inode(inode))
 686                 return -EIO;
 687
 688         /*
 689          * Make sure writepages on the same page are not mixed up with
 690          * plain writes.
 691          */
 692         fuse_wait_on_page_writeback(inode, page->index);
 693
 694         req = fuse_get_req(fc);
 695         if (IS_ERR(req))
 696                 return PTR_ERR(req);
 697
 698         req->num_pages = 1;
 699         req->pages[0] = page;
 700         req->page_offset = offset;
 701         nres = fuse_send_write(req, file, inode, pos, count, NULL);
 702         err = req->out.h.error;
 703         fuse_put_request(fc, req);
 704         if (!err && !nres)
 705                 err = -EIO;
 706         if (!err) {
 707                 pos += nres;
 708                 fuse_write_update_size(inode, pos);
 709                 if (count == PAGE_CACHE_SIZE)
 710                         SetPageUptodate(page);
 711         }
 712         fuse_invalidate_attr(inode);
 713         return err ? err : nres;
 714 }
 715
 716 static int fuse_write_end(struct file *file, struct address_space *mapping,
 717                         loff_t pos, unsigned len, unsigned copied,
 718                         struct page *page, void *fsdata)
 719 {
 720         struct inode *inode = mapping->host;
 721         int res = 0;
 722
 723         if (copied)
 724                 res = fuse_buffered_write(file, inode, pos, copied, page);
 725
 726         unlock_page(page);
 727         page_cache_release(page);
 728         return res;
 729 }
 730
 731 static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
 732                                     struct inode *inode, loff_t pos,
 733                                     size_t count)
 734 {
 735         size_t res;
 736         unsigned offset;
 737         unsigned i;
 738
 739         for (i = 0; i < req->num_pages; i++)
 740                 fuse_wait_on_page_writeback(inode, req->pages[i]->index);
 741
 742         res = fuse_send_write(req, file, inode, pos, count, NULL);
 743
 744         offset = req->page_offset;
 745         count = res;
 746         for (i = 0; i < req->num_pages; i++) {
 747                 struct page *page = req->pages[i];
 748
 749                 if (!req->out.h.error && !offset && count >= PAGE_CACHE_SIZE)
 750                         SetPageUptodate(page);
 751
 752                 if (count > PAGE_CACHE_SIZE - offset)
 753                         count -= PAGE_CACHE_SIZE - offset;
 754                 else
 755                         count = 0;
 756                 offset = 0;
 757
 758                 unlock_page(page);
 759                 page_cache_release(page);
 760         }
 761
 762         return res;
 763 }
 764
 765 static ssize_t fuse_fill_write_pages(struct fuse_req *req,
 766                                struct address_space *mapping,
 767                                struct iov_iter *ii, loff_t pos)
 768 {
 769         struct fuse_conn *fc = get_fuse_conn(mapping->host);
 770         unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
 771         size_t count = 0;
 772         int err;
 773
 774         req->page_offset = offset;
 775
 776         do {
 777                 size_t tmp;
 778                 struct page *page;
 779                 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 780                 size_t bytes = min_t(size_t, PAGE_CACHE_SIZE - offset,
 781                                      iov_iter_count(ii));
 782
 783                 bytes = min_t(size_t, bytes, fc->max_write - count);
 784
 785  again:
 786                 err = -EFAULT;
 787                 if (iov_iter_fault_in_readable(ii, bytes))
 788                         break;
 789
 790                 err = -ENOMEM;
 791                 page = __grab_cache_page(mapping, index);
 792                 if (!page)
 793                         break;
 794
 795                 pagefault_disable();
 796                 tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
 797                 pagefault_enable();
 798                 flush_dcache_page(page);
 799
 800                 if (!tmp) {
 801                         unlock_page(page);
 802                         page_cache_release(page);
 803                         bytes = min(bytes, iov_iter_single_seg_count(ii));
 804                         goto again;
 805                 }
 806
 807                 err = 0;
 808                 req->pages[req->num_pages] = page;
 809                 req->num_pages++;
 810
 811                 iov_iter_advance(ii, tmp);
 812                 count += tmp;
 813                 pos += tmp;
 814                 offset += tmp;
 815                 if (offset == PAGE_CACHE_SIZE)
 816                         offset = 0;
 817
 818                 if (!fc->big_writes)
 819                         break;
 820         } while (iov_iter_count(ii) && count < fc->max_write &&
 821                  req->num_pages < FUSE_MAX_PAGES_PER_REQ && offset == 0);
 822
 823         return count > 0 ? count : err;
 824 }
 825
 826 static ssize_t fuse_perform_write(struct file *file,
 827                                   struct address_space *mapping,
 828                                   struct iov_iter *ii, loff_t pos)
 829 {
 830         struct inode *inode = mapping->host;
 831         struct fuse_conn *fc = get_fuse_conn(inode);
 832         int err = 0;
 833         ssize_t res = 0;
 834
 835         if (is_bad_inode(inode))
 836                 return -EIO;
 837
 838         do {
 839                 struct fuse_req *req;
 840                 ssize_t count;
 841
 842                 req = fuse_get_req(fc);
 843                 if (IS_ERR(req)) {
 844                         err = PTR_ERR(req);
 845                         break;
 846                 }
 847
 848                 count = fuse_fill_write_pages(req, mapping, ii, pos);
 849                 if (count <= 0) {
 850                         err = count;
 851                 } else {
 852                         size_t num_written;
 853
 854                         num_written = fuse_send_write_pages(req, file, inode,
 855                                                             pos, count);
 856                         err = req->out.h.error;
 857                         if (!err) {
 858                                 res += num_written;
 859                                 pos += num_written;
 860
 861                                 /* break out of the loop on short write */
 862                                 if (num_written != count)
 863                                         err = -EIO;
 864                         }
 865                 }
 866                 fuse_put_request(fc, req);
 867         } while (!err && iov_iter_count(ii));
 868
 869         if (res > 0)
 870                 fuse_write_update_size(inode, pos);
 871
 872         fuse_invalidate_attr(inode);
 873
 874         return res > 0 ? res : err;
 875 }
 876
 877 static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 878                                    unsigned long nr_segs, loff_t pos)
 879 {
 880         struct file *file = iocb->ki_filp;
 881         struct address_space *mapping = file->f_mapping;
 882         size_t count = 0;
 883         ssize_t written = 0;
 884         struct inode *inode = mapping->host;
 885         ssize_t err;
 886         struct iov_iter i;
 887
 888         WARN_ON(iocb->ki_pos != pos);
 889
 890         err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
 891         if (err)
 892                 return err;
 893
 894         mutex_lock(&inode->i_mutex);
 895         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 896
 897         /* We can write back this queue in page reclaim */
 898         current->backing_dev_info = mapping->backing_dev_info;
 899
 900         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
 901         if (err)
 902                 goto out;
 903
 904         if (count == 0)
 905                 goto out;
 906
 907         err = file_remove_suid(file);
 908         if (err)
 909                 goto out;
 910
 911         file_update_time(file);
 912
 913         iov_iter_init(&i, iov, nr_segs, count, 0);
 914         written = fuse_perform_write(file, mapping, &i, pos);
 915         if (written >= 0)
 916                 iocb->ki_pos = pos + written;
 917
 918 out:
 919         current->backing_dev_info = NULL;
 920         mutex_unlock(&inode->i_mutex);
 921
 922         return written ? written : err;
 923 }
 924
 925 static void fuse_release_user_pages(struct fuse_req *req, int write)
 926 {
 927         unsigned i;
 928
 929         for (i = 0; i < req->num_pages; i++) {
 930                 struct page *page = req->pages[i];
 931                 if (write)
 932                         set_page_dirty_lock(page);
 933                 put_page(page);
 934         }
 935 }
 936
 937 static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
 938                                unsigned nbytes, int write)
 939 {
 940         unsigned long user_addr = (unsigned long) buf;
 941         unsigned offset = user_addr & ~PAGE_MASK;
 942         int npages;
 943
 944         /* This doesn't work with nfsd */
 945         if (!current->mm)
 946                 return -EPERM;
 947
 948         nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
 949         npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
 950         npages = clamp(npages, 1, FUSE_MAX_PAGES_PER_REQ);
 951         down_read(&current->mm->mmap_sem);
 952         npages = get_user_pages(current, current->mm, user_addr, npages, write,
 953                                 0, req->pages, NULL);
 954         up_read(&current->mm->mmap_sem);
 955         if (npages < 0)
 956                 return npages;
 957
 958         req->num_pages = npages;
 959         req->page_offset = offset;
 960         return 0;
 961 }
 962
 963 static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
 964                               size_t count, loff_t *ppos, int write)
 965 {
 966         struct inode *inode = file->f_path.dentry->d_inode;
 967         struct fuse_conn *fc = get_fuse_conn(inode);
 968         size_t nmax = write ? fc->max_write : fc->max_read;
 969         loff_t pos = *ppos;
 970         ssize_t res = 0;
 971         struct fuse_req *req;
 972
 973         if (is_bad_inode(inode))
 974                 return -EIO;
 975
 976         req = fuse_get_req(fc);
 977         if (IS_ERR(req))
 978                 return PTR_ERR(req);
 979
 980         while (count) {
 981                 size_t nres;
 982                 size_t nbytes_limit = min(count, nmax);
 983                 size_t nbytes;
 984                 int err = fuse_get_user_pages(req, buf, nbytes_limit, !write);
 985                 if (err) {
 986                         res = err;
 987                         break;
 988                 }
 989                 nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
 990                 nbytes = min(nbytes_limit, nbytes);
 991                 if (write)
 992                         nres = fuse_send_write(req, file, inode, pos, nbytes,
 993                                                current->files);
 994                 else
 995                         nres = fuse_send_read(req, file, inode, pos, nbytes,
 996                                               current->files);
 997                 fuse_release_user_pages(req, !write);
 998                 if (req->out.h.error) {
 999                         if (!res)
1000                                 res = req->out.h.error;
1001                         break;
1002                 } else if (nres > nbytes) {
1003                         res = -EIO;
1004                         break;
1005                 }
1006                 count -= nres;
1007                 res += nres;
1008                 pos += nres;
1009                 buf += nres;
1010                 if (nres != nbytes)
1011                         break;
1012                 if (count) {
1013                         fuse_put_request(fc, req);
1014                         req = fuse_get_req(fc);
1015                         if (IS_ERR(req))
1016                                 break;
1017                 }
1018         }
1019         fuse_put_request(fc, req);
1020         if (res > 0) {
1021                 if (write)
1022                         fuse_write_update_size(inode, pos);
1023                 *ppos = pos;
1024         }
1025         fuse_invalidate_attr(inode);
1026
1027         return res;
1028 }
1029
1030 static ssize_t fuse_direct_read(struct file *file, char __user *buf,
1031                                      size_t count, loff_t *ppos)
1032 {
1033         return fuse_direct_io(file, buf, count, ppos, 0);
1034 }
1035
1036 static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
1037                                  size_t count, loff_t *ppos)
1038 {
1039         struct inode *inode = file->f_path.dentry->d_inode;
1040         ssize_t res;
1041         /* Don't allow parallel writes to the same file */
1042         mutex_lock(&inode->i_mutex);
1043         res = generic_write_checks(file, ppos, &count, 0);
1044         if (!res)
1045                 res = fuse_direct_io(file, buf, count, ppos, 1);
1046         mutex_unlock(&inode->i_mutex);
1047         return res;
1048 }
1049
1050 static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
1051 {
1052         __free_page(req->pages[0]);
1053         fuse_file_put(req->ff);
1054 }
1055
1056 static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
1057 {
1058         struct inode *inode = req->inode;
1059         struct fuse_inode *fi = get_fuse_inode(inode);
1060         struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
1061
1062         list_del(&req->writepages_entry);
1063         dec_bdi_stat(bdi, BDI_WRITEBACK);
1064         dec_zone_page_state(req->pages[0], NR_WRITEBACK_TEMP);
1065         bdi_writeout_inc(bdi);
1066         wake_up(&fi->page_waitq);
1067 }
1068
1069 /* Called under fc->lock, may release and reacquire it */
1070 static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req)
1071 {
1072         struct fuse_inode *fi = get_fuse_inode(req->inode);
1073         loff_t size = i_size_read(req->inode);
1074         struct fuse_write_in *inarg = &req->misc.write.in;
1075
1076         if (!fc->connected)
1077                 goto out_free;
1078
1079         if (inarg->offset + PAGE_CACHE_SIZE <= size) {
1080                 inarg->size = PAGE_CACHE_SIZE;
1081         } else if (inarg->offset < size) {
1082                 inarg->size = size & (PAGE_CACHE_SIZE - 1);
1083         } else {
1084                 /* Got truncated off completely */
1085                 goto out_free;
1086         }
1087
1088         req->in.args[1].size = inarg->size;
1089         fi->writectr++;
1090         fuse_request_send_background_locked(fc, req);
1091         return;
1092
1093  out_free:
1094         fuse_writepage_finish(fc, req);
1095         spin_unlock(&fc->lock);
1096         fuse_writepage_free(fc, req);
1097         fuse_put_request(fc, req);
1098         spin_lock(&fc->lock);
1099 }
1100
1101 /*
1102  * If fi->writectr is positive (no truncate or fsync going on) send
1103  * all queued writepage requests.
1104  *
1105  * Called with fc->lock
1106  */
1107 void fuse_flush_writepages(struct inode *inode)
1108 {
1109         struct fuse_conn *fc = get_fuse_conn(inode);
1110         struct fuse_inode *fi = get_fuse_inode(inode);
1111         struct fuse_req *req;
1112
1113         while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
1114                 req = list_entry(fi->queued_writes.next, struct fuse_req, list);
1115                 list_del_init(&req->list);
1116                 fuse_send_writepage(fc, req);
1117         }
1118 }
1119
1120 static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
1121 {
1122         struct inode *inode = req->inode;
1123         struct fuse_inode *fi = get_fuse_inode(inode);
1124
1125         mapping_set_error(inode->i_mapping, req->out.h.error);
1126         spin_lock(&fc->lock);
1127         fi->writectr--;
1128         fuse_writepage_finish(fc, req);
1129         spin_unlock(&fc->lock);
1130         fuse_writepage_free(fc, req);
1131 }
1132
1133 static int fuse_writepage_locked(struct page *page)
1134 {
1135         struct address_space *mapping = page->mapping;
1136         struct inode *inode = mapping->host;
1137         struct fuse_conn *fc = get_fuse_conn(inode);
1138         struct fuse_inode *fi = get_fuse_inode(inode);
1139         struct fuse_req *req;
1140         struct fuse_file *ff;
1141         struct page *tmp_page;
1142
1143         set_page_writeback(page);
1144
1145         req = fuse_request_alloc_nofs();
1146         if (!req)
1147                 goto err;
1148
1149         tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
1150         if (!tmp_page)
1151                 goto err_free;
1152
1153         spin_lock(&fc->lock);
1154         BUG_ON(list_empty(&fi->write_files));
1155         ff = list_entry(fi->write_files.next, struct fuse_file, write_entry);
1156         req->ff = fuse_file_get(ff);
1157         spin_unlock(&fc->lock);
1158
1159         fuse_write_fill(req, NULL, ff, inode, page_offset(page), 0, 1);
1160
1161         copy_highpage(tmp_page, page);
1162         req->num_pages = 1;
1163         req->pages[0] = tmp_page;
1164         req->page_offset = 0;
1165         req->end = fuse_writepage_end;
1166         req->inode = inode;
1167
1168         inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK);
1169         inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
1170         end_page_writeback(page);
1171
1172         spin_lock(&fc->lock);
1173         list_add(&req->writepages_entry, &fi->writepages);
1174         list_add_tail(&req->list, &fi->queued_writes);
1175         fuse_flush_writepages(inode);
1176         spin_unlock(&fc->lock);
1177
1178         return 0;
1179
1180 err_free:
1181         fuse_request_free(req);
1182 err:
1183         end_page_writeback(page);
1184         return -ENOMEM;
1185 }
1186
1187 static int fuse_writepage(struct page *page, struct writeback_control *wbc)
1188 {
1189         int err;
1190
1191         err = fuse_writepage_locked(page);
1192         unlock_page(page);
1193
1194         return err;
1195 }
1196
1197 static int fuse_launder_page(struct page *page)
1198 {
1199         int err = 0;
1200         if (clear_page_dirty_for_io(page)) {
1201                 struct inode *inode = page->mapping->host;
1202                 err = fuse_writepage_locked(page);
1203                 if (!err)
1204                         fuse_wait_on_page_writeback(inode, page->index);
1205         }
1206         return err;
1207 }
1208
1209 /*
1210  * Write back dirty pages now, because there may not be any suitable
1211  * open files later
1212  */
1213 static void fuse_vma_close(struct vm_area_struct *vma)
1214 {
1215         filemap_write_and_wait(vma->vm_file->f_mapping);
1216 }
1217
1218 /*
1219  * Wait for writeback against this page to complete before allowing it
1220  * to be marked dirty again, and hence written back again, possibly
1221  * before the previous writepage completed.
1222  *
1223  * Block here, instead of in ->writepage(), so that the userspace fs
1224  * can only block processes actually operating on the filesystem.
1225  *
1226  * Otherwise unprivileged userspace fs would be able to block
1227  * unrelated:
1228  *
1229  * - page migration
1230  * - sync(2)
1231  * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
1232  */
1233 static int fuse_page_mkwrite(struct vm_area_struct *vma, struct page *page)
1234 {
1235         /*
1236          * Don't use page->mapping as it may become NULL from a
1237          * concurrent truncate.
1238          */
1239         struct inode *inode = vma->vm_file->f_mapping->host;
1240
1241         fuse_wait_on_page_writeback(inode, page->index);
1242         return 0;
1243 }
1244
1245 static struct vm_operations_struct fuse_file_vm_ops = {
1246         .close          = fuse_vma_close,
1247         .fault          = filemap_fault,
1248         .page_mkwrite   = fuse_page_mkwrite,
1249 };
1250
1251 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
1252 {
1253         if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) {
1254                 struct inode *inode = file->f_dentry->d_inode;
1255                 struct fuse_conn *fc = get_fuse_conn(inode);
1256                 struct fuse_inode *fi = get_fuse_inode(inode);
1257                 struct fuse_file *ff = file->private_data;
1258                 /*
1259                  * file may be written through mmap, so chain it onto the
1260                  * inodes's write_file list
1261                  */
1262                 spin_lock(&fc->lock);
1263                 if (list_empty(&ff->write_entry))
1264                         list_add(&ff->write_entry, &fi->write_files);
1265                 spin_unlock(&fc->lock);
1266         }
1267         file_accessed(file);
1268         vma->vm_ops = &fuse_file_vm_ops;
1269         return 0;
1270 }
1271
1272 static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
1273                                   struct file_lock *fl)
1274 {
1275         switch (ffl->type) {
1276         case F_UNLCK:
1277                 break;
1278
1279         case F_RDLCK:
1280         case F_WRLCK:
1281                 if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
1282                     ffl->end < ffl->start)
1283                         return -EIO;
1284
1285                 fl->fl_start = ffl->start;
1286                 fl->fl_end = ffl->end;
1287                 fl->fl_pid = ffl->pid;
1288                 break;
1289
1290         default:
1291                 return -EIO;
1292         }
1293         fl->fl_type = ffl->type;
1294         return 0;
1295 }
1296
1297 static void fuse_lk_fill(struct fuse_req *req, struct file *file,
1298                          const struct file_lock *fl, int opcode, pid_t pid,
1299                          int flock)
1300 {
1301         struct inode *inode = file->f_path.dentry->d_inode;
1302         struct fuse_conn *fc = get_fuse_conn(inode);
1303         struct fuse_file *ff = file->private_data;
1304         struct fuse_lk_in *arg = &req->misc.lk_in;
1305
1306         arg->fh = ff->fh;
1307         arg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
1308         arg->lk.start = fl->fl_start;
1309         arg->lk.end = fl->fl_end;
1310         arg->lk.type = fl->fl_type;
1311         arg->lk.pid = pid;
1312         if (flock)
1313                 arg->lk_flags |= FUSE_LK_FLOCK;
1314         req->in.h.opcode = opcode;
1315         req->in.h.nodeid = get_node_id(inode);
1316         req->in.numargs = 1;
1317         req->in.args[0].size = sizeof(*arg);
1318         req->in.args[0].value = arg;
1319 }
1320
1321 static int fuse_getlk(struct file *file, struct file_lock *fl)
1322 {
1323         struct inode *inode = file->f_path.dentry->d_inode;
1324         struct fuse_conn *fc = get_fuse_conn(inode);
1325         struct fuse_req *req;
1326         struct fuse_lk_out outarg;
1327         int err;
1328
1329         req = fuse_get_req(fc);
1330         if (IS_ERR(req))
1331                 return PTR_ERR(req);
1332
1333         fuse_lk_fill(req, file, fl, FUSE_GETLK, 0, 0);
1334         req->out.numargs = 1;
1335         req->out.args[0].size = sizeof(outarg);
1336         req->out.args[0].value = &outarg;
1337         fuse_request_send(fc, req);
1338         err = req->out.h.error;
1339         fuse_put_request(fc, req);
1340         if (!err)
1341                 err = convert_fuse_file_lock(&outarg.lk, fl);
1342
1343         return err;
1344 }
1345
1346 static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
1347 {
1348         struct inode *inode = file->f_path.dentry->d_inode;
1349         struct fuse_conn *fc = get_fuse_conn(inode);
1350         struct fuse_req *req;
1351         int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
1352         pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
1353         int err;
1354
1355         if (fl->fl_lmops && fl->fl_lmops->fl_grant) {
1356                 /* NLM needs asynchronous locks, which we don't support yet */
1357                 return -ENOLCK;
1358         }
1359
1360         /* Unlock on close is handled by the flush method */
1361         if (fl->fl_flags & FL_CLOSE)
1362                 return 0;
1363
1364         req = fuse_get_req(fc);
1365         if (IS_ERR(req))
1366                 return PTR_ERR(req);
1367
1368         fuse_lk_fill(req, file, fl, opcode, pid, flock);
1369         fuse_request_send(fc, req);
1370         err = req->out.h.error;
1371         /* locking is restartable */
1372         if (err == -EINTR)
1373                 err = -ERESTARTSYS;
1374         fuse_put_request(fc, req);
1375         return err;
1376 }
1377
1378 static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
1379 {
1380         struct inode *inode = file->f_path.dentry->d_inode;
1381         struct fuse_conn *fc = get_fuse_conn(inode);
1382         int err;
1383
1384         if (cmd == F_CANCELLK) {
1385                 err = 0;
1386         } else if (cmd == F_GETLK) {
1387                 if (fc->no_lock) {
1388                         posix_test_lock(file, fl);
1389                         err = 0;
1390                 } else
1391                         err = fuse_getlk(file, fl);
1392         } else {
1393                 if (fc->no_lock)
1394                         err = posix_lock_file(file, fl, NULL);
1395                 else
1396                         err = fuse_setlk(file, fl, 0);
1397         }
1398         return err;
1399 }
1400
1401 static int fuse_file_flock(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 (fc->no_lock) {
1408                 err = flock_lock_file_wait(file, fl);
1409         } else {
1410                 /* emulate flock with POSIX locks */
1411                 fl->fl_owner = (fl_owner_t) file;
1412                 err = fuse_setlk(file, fl, 1);
1413         }
1414
1415         return err;
1416 }
1417
1418 static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
1419 {
1420         struct inode *inode = mapping->host;
1421         struct fuse_conn *fc = get_fuse_conn(inode);
1422         struct fuse_req *req;
1423         struct fuse_bmap_in inarg;
1424         struct fuse_bmap_out outarg;
1425         int err;
1426
1427         if (!inode->i_sb->s_bdev || fc->no_bmap)
1428                 return 0;
1429
1430         req = fuse_get_req(fc);
1431         if (IS_ERR(req))
1432                 return 0;
1433
1434         memset(&inarg, 0, sizeof(inarg));
1435         inarg.block = block;
1436         inarg.blocksize = inode->i_sb->s_blocksize;
1437         req->in.h.opcode = FUSE_BMAP;
1438         req->in.h.nodeid = get_node_id(inode);
1439         req->in.numargs = 1;
1440         req->in.args[0].size = sizeof(inarg);
1441         req->in.args[0].value = &inarg;
1442         req->out.numargs = 1;
1443         req->out.args[0].size = sizeof(outarg);
1444         req->out.args[0].value = &outarg;
1445         fuse_request_send(fc, req);
1446         err = req->out.h.error;
1447         fuse_put_request(fc, req);
1448         if (err == -ENOSYS)
1449                 fc->no_bmap = 1;
1450
1451         return err ? 0 : outarg.block;
1452 }
1453
1454 static loff_t fuse_file_llseek(struct file *file, loff_t offset, int origin)
1455 {
1456         loff_t retval;
1457         struct inode *inode = file->f_path.dentry->d_inode;
1458
1459         mutex_lock(&inode->i_mutex);
1460         switch (origin) {
1461         case SEEK_END:
1462                 retval = fuse_update_attributes(inode, NULL, file, NULL);
1463                 if (retval)
1464                         return retval;
1465                 offset += i_size_read(inode);
1466                 break;
1467         case SEEK_CUR:
1468                 offset += file->f_pos;
1469         }
1470         retval = -EINVAL;
1471         if (offset >= 0 && offset <= inode->i_sb->s_maxbytes) {
1472                 if (offset != file->f_pos) {
1473                         file->f_pos = offset;
1474                         file->f_version = 0;
1475                 }
1476                 retval = offset;
1477         }
1478         mutex_unlock(&inode->i_mutex);
1479         return retval;
1480 }
1481
1482 static int fuse_ioctl_copy_user(struct page **pages, struct iovec *iov,
1483                         unsigned int nr_segs, size_t bytes, bool to_user)
1484 {
1485         struct iov_iter ii;
1486         int page_idx = 0;
1487
1488         if (!bytes)
1489                 return 0;
1490
1491         iov_iter_init(&ii, iov, nr_segs, bytes, 0);
1492
1493         while (iov_iter_count(&ii)) {
1494                 struct page *page = pages[page_idx++];
1495                 size_t todo = min_t(size_t, PAGE_SIZE, iov_iter_count(&ii));
1496                 void *kaddr, *map;
1497
1498                 kaddr = map = kmap(page);
1499
1500                 while (todo) {
1501                         char __user *uaddr = ii.iov->iov_base + ii.iov_offset;
1502                         size_t iov_len = ii.iov->iov_len - ii.iov_offset;
1503                         size_t copy = min(todo, iov_len);
1504                         size_t left;
1505
1506                         if (!to_user)
1507                                 left = copy_from_user(kaddr, uaddr, copy);
1508                         else
1509                                 left = copy_to_user(uaddr, kaddr, copy);
1510
1511                         if (unlikely(left))
1512                                 return -EFAULT;
1513
1514                         iov_iter_advance(&ii, copy);
1515                         todo -= copy;
1516                         kaddr += copy;
1517                 }
1518
1519                 kunmap(map);
1520         }
1521
1522         return 0;
1523 }
1524
1525 /*
1526  * For ioctls, there is no generic way to determine how much memory
1527  * needs to be read and/or written.  Furthermore, ioctls are allowed
1528  * to dereference the passed pointer, so the parameter requires deep
1529  * copying but FUSE has no idea whatsoever about what to copy in or
1530  * out.
1531  *
1532  * This is solved by allowing FUSE server to retry ioctl with
1533  * necessary in/out iovecs.  Let's assume the ioctl implementation
1534  * needs to read in the following structure.
1535  *
1536  * struct a {
1537  *      char    *buf;
1538  *      size_t  buflen;
1539  * }
1540  *
1541  * On the first callout to FUSE server, inarg->in_size and
1542  * inarg->out_size will be NULL; then, the server completes the ioctl
1543  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
1544  * the actual iov array to
1545  *
1546  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
1547  *
1548  * which tells FUSE to copy in the requested area and retry the ioctl.
1549  * On the second round, the server has access to the structure and
1550  * from that it can tell what to look for next, so on the invocation,
1551  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
1552  *
1553  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
1554  *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
1555  *
1556  * FUSE will copy both struct a and the pointed buffer from the
1557  * process doing the ioctl and retry ioctl with both struct a and the
1558  * buffer.
1559  *
1560  * This time, FUSE server has everything it needs and completes ioctl
1561  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
1562  *
1563  * Copying data out works the same way.
1564  *
1565  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
1566  * automatically initializes in and out iovs by decoding @cmd with
1567  * _IOC_* macros and the server is not allowed to request RETRY.  This
1568  * limits ioctl data transfers to well-formed ioctls and is the forced
1569  * behavior for all FUSE servers.
1570  */
1571 static long fuse_file_do_ioctl(struct file *file, unsigned int cmd,
1572                                unsigned long arg, unsigned int flags)
1573 {
1574         struct inode *inode = file->f_dentry->d_inode;
1575         struct fuse_file *ff = file->private_data;
1576         struct fuse_conn *fc = get_fuse_conn(inode);
1577         struct fuse_ioctl_in inarg = {
1578                 .fh = ff->fh,
1579                 .cmd = cmd,
1580                 .arg = arg,
1581                 .flags = flags
1582         };
1583         struct fuse_ioctl_out outarg;
1584         struct fuse_req *req = NULL;
1585         struct page **pages = NULL;
1586         struct page *iov_page = NULL;
1587         struct iovec *in_iov = NULL, *out_iov = NULL;
1588         unsigned int in_iovs = 0, out_iovs = 0, num_pages = 0, max_pages;
1589         size_t in_size, out_size, transferred;
1590         int err;
1591
1592         /* assume all the iovs returned by client always fits in a page */
1593         BUILD_BUG_ON(sizeof(struct iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
1594
1595         if (!fuse_allow_task(fc, current))
1596                 return -EACCES;
1597
1598         err = -EIO;
1599         if (is_bad_inode(inode))
1600                 goto out;
1601
1602         err = -ENOMEM;
1603         pages = kzalloc(sizeof(pages[0]) * FUSE_MAX_PAGES_PER_REQ, GFP_KERNEL);
1604         iov_page = alloc_page(GFP_KERNEL);
1605         if (!pages || !iov_page)
1606                 goto out;
1607
1608         /*
1609          * If restricted, initialize IO parameters as encoded in @cmd.
1610          * RETRY from server is not allowed.
1611          */
1612         if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
1613                 struct iovec *iov = page_address(iov_page);
1614
1615                 iov->iov_base = (void __user *)arg;
1616                 iov->iov_len = _IOC_SIZE(cmd);
1617
1618                 if (_IOC_DIR(cmd) & _IOC_WRITE) {
1619                         in_iov = iov;
1620                         in_iovs = 1;
1621                 }
1622
1623                 if (_IOC_DIR(cmd) & _IOC_READ) {
1624                         out_iov = iov;
1625                         out_iovs = 1;
1626                 }
1627         }
1628
1629  retry:
1630         inarg.in_size = in_size = iov_length(in_iov, in_iovs);
1631         inarg.out_size = out_size = iov_length(out_iov, out_iovs);
1632
1633         /*
1634          * Out data can be used either for actual out data or iovs,
1635          * make sure there always is at least one page.
1636          */
1637         out_size = max_t(size_t, out_size, PAGE_SIZE);
1638         max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
1639
1640         /* make sure there are enough buffer pages and init request with them */
1641         err = -ENOMEM;
1642         if (max_pages > FUSE_MAX_PAGES_PER_REQ)
1643                 goto out;
1644         while (num_pages < max_pages) {
1645                 pages[num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
1646                 if (!pages[num_pages])
1647                         goto out;
1648                 num_pages++;
1649         }
1650
1651         req = fuse_get_req(fc);
1652         if (IS_ERR(req)) {
1653                 err = PTR_ERR(req);
1654                 req = NULL;
1655                 goto out;
1656         }
1657         memcpy(req->pages, pages, sizeof(req->pages[0]) * num_pages);
1658         req->num_pages = num_pages;
1659
1660         /* okay, let's send it to the client */
1661         req->in.h.opcode = FUSE_IOCTL;
1662         req->in.h.nodeid = get_node_id(inode);
1663         req->in.numargs = 1;
1664         req->in.args[0].size = sizeof(inarg);
1665         req->in.args[0].value = &inarg;
1666         if (in_size) {
1667                 req->in.numargs++;
1668                 req->in.args[1].size = in_size;
1669                 req->in.argpages = 1;
1670
1671                 err = fuse_ioctl_copy_user(pages, in_iov, in_iovs, in_size,
1672                                            false);
1673                 if (err)
1674                         goto out;
1675         }
1676
1677         req->out.numargs = 2;
1678         req->out.args[0].size = sizeof(outarg);
1679         req->out.args[0].value = &outarg;
1680         req->out.args[1].size = out_size;
1681         req->out.argpages = 1;
1682         req->out.argvar = 1;
1683
1684         fuse_request_send(fc, req);
1685         err = req->out.h.error;
1686         transferred = req->out.args[1].size;
1687         fuse_put_request(fc, req);
1688         req = NULL;
1689         if (err)
1690                 goto out;
1691
1692         /* did it ask for retry? */
1693         if (outarg.flags & FUSE_IOCTL_RETRY) {
1694                 char *vaddr;
1695
1696                 /* no retry if in restricted mode */
1697                 err = -EIO;
1698                 if (!(flags & FUSE_IOCTL_UNRESTRICTED))
1699                         goto out;
1700
1701                 in_iovs = outarg.in_iovs;
1702                 out_iovs = outarg.out_iovs;
1703
1704                 /*
1705                  * Make sure things are in boundary, separate checks
1706                  * are to protect against overflow.
1707                  */
1708                 err = -ENOMEM;
1709                 if (in_iovs > FUSE_IOCTL_MAX_IOV ||
1710                     out_iovs > FUSE_IOCTL_MAX_IOV ||
1711                     in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
1712                         goto out;
1713
1714                 err = -EIO;
1715                 if ((in_iovs + out_iovs) * sizeof(struct iovec) != transferred)
1716                         goto out;
1717
1718                 /* okay, copy in iovs and retry */
1719                 vaddr = kmap_atomic(pages[0], KM_USER0);
1720                 memcpy(page_address(iov_page), vaddr, transferred);
1721                 kunmap_atomic(vaddr, KM_USER0);
1722
1723                 in_iov = page_address(iov_page);
1724                 out_iov = in_iov + in_iovs;
1725
1726                 goto retry;
1727         }
1728
1729         err = -EIO;
1730         if (transferred > inarg.out_size)
1731                 goto out;
1732
1733         err = fuse_ioctl_copy_user(pages, out_iov, out_iovs, transferred, true);
1734  out:
1735         if (req)
1736                 fuse_put_request(fc, req);
1737         if (iov_page)
1738                 __free_page(iov_page);
1739         while (num_pages)
1740                 __free_page(pages[--num_pages]);
1741         kfree(pages);
1742
1743         return err ? err : outarg.result;
1744 }
1745
1746 static long fuse_file_ioctl(struct file *file, unsigned int cmd,
1747                             unsigned long arg)
1748 {
1749         return fuse_file_do_ioctl(file, cmd, arg, 0);
1750 }
1751
1752 static long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
1753                                    unsigned long arg)
1754 {
1755         return fuse_file_do_ioctl(file, cmd, arg, FUSE_IOCTL_COMPAT);
1756 }
1757
1758 /*
1759  * All files which have been polled are linked to RB tree
1760  * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
1761  * find the matching one.
1762  */
1763 static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
1764                                               struct rb_node **parent_out)
1765 {
1766         struct rb_node **link = &fc->polled_files.rb_node;
1767         struct rb_node *last = NULL;
1768
1769         while (*link) {
1770                 struct fuse_file *ff;
1771
1772                 last = *link;
1773                 ff = rb_entry(last, struct fuse_file, polled_node);
1774
1775                 if (kh < ff->kh)
1776                         link = &last->rb_left;
1777                 else if (kh > ff->kh)
1778                         link = &last->rb_right;
1779                 else
1780                         return link;
1781         }
1782
1783         if (parent_out)
1784                 *parent_out = last;
1785         return link;
1786 }
1787
1788 /*
1789  * The file is about to be polled.  Make sure it's on the polled_files
1790  * RB tree.  Note that files once added to the polled_files tree are
1791  * not removed before the file is released.  This is because a file
1792  * polled once is likely to be polled again.
1793  */
1794 static void fuse_register_polled_file(struct fuse_conn *fc,
1795                                       struct fuse_file *ff)
1796 {
1797         spin_lock(&fc->lock);
1798         if (RB_EMPTY_NODE(&ff->polled_node)) {
1799                 struct rb_node **link, *parent;
1800
1801                 link = fuse_find_polled_node(fc, ff->kh, &parent);
1802                 BUG_ON(*link);
1803                 rb_link_node(&ff->polled_node, parent, link);
1804                 rb_insert_color(&ff->polled_node, &fc->polled_files);
1805         }
1806         spin_unlock(&fc->lock);
1807 }
1808
1809 static unsigned fuse_file_poll(struct file *file, poll_table *wait)
1810 {
1811         struct inode *inode = file->f_dentry->d_inode;
1812         struct fuse_file *ff = file->private_data;
1813         struct fuse_conn *fc = get_fuse_conn(inode);
1814         struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
1815         struct fuse_poll_out outarg;
1816         struct fuse_req *req;
1817         int err;
1818
1819         if (fc->no_poll)
1820                 return DEFAULT_POLLMASK;
1821
1822         poll_wait(file, &ff->poll_wait, wait);
1823
1824         /*
1825          * Ask for notification iff there's someone waiting for it.
1826          * The client may ignore the flag and always notify.
1827          */
1828         if (waitqueue_active(&ff->poll_wait)) {
1829                 inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
1830                 fuse_register_polled_file(fc, ff);
1831         }
1832
1833         req = fuse_get_req(fc);
1834         if (IS_ERR(req))
1835                 return PTR_ERR(req);
1836
1837         req->in.h.opcode = FUSE_POLL;
1838         req->in.h.nodeid = get_node_id(inode);
1839         req->in.numargs = 1;
1840         req->in.args[0].size = sizeof(inarg);
1841         req->in.args[0].value = &inarg;
1842         req->out.numargs = 1;
1843         req->out.args[0].size = sizeof(outarg);
1844         req->out.args[0].value = &outarg;
1845         fuse_request_send(fc, req);
1846         err = req->out.h.error;
1847         fuse_put_request(fc, req);
1848
1849         if (!err)
1850                 return outarg.revents;
1851         if (err == -ENOSYS) {
1852                 fc->no_poll = 1;
1853                 return DEFAULT_POLLMASK;
1854         }
1855         return POLLERR;
1856 }
1857
1858 /*
1859  * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
1860  * wakes up the poll waiters.
1861  */
1862 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
1863                             struct fuse_notify_poll_wakeup_out *outarg)
1864 {
1865         u64 kh = outarg->kh;
1866         struct rb_node **link;
1867
1868         spin_lock(&fc->lock);
1869
1870         link = fuse_find_polled_node(fc, kh, NULL);
1871         if (*link) {
1872                 struct fuse_file *ff;
1873
1874                 ff = rb_entry(*link, struct fuse_file, polled_node);
1875                 wake_up_interruptible_sync(&ff->poll_wait);
1876         }
1877
1878         spin_unlock(&fc->lock);
1879         return 0;
1880 }
1881
1882 static const struct file_operations fuse_file_operations = {
1883         .llseek         = fuse_file_llseek,
1884         .read           = do_sync_read,
1885         .aio_read       = fuse_file_aio_read,
1886         .write          = do_sync_write,
1887         .aio_write      = fuse_file_aio_write,
1888         .mmap           = fuse_file_mmap,
1889         .open           = fuse_open,
1890         .flush          = fuse_flush,
1891         .release        = fuse_release,
1892         .fsync          = fuse_fsync,
1893         .lock           = fuse_file_lock,
1894         .flock          = fuse_file_flock,
1895         .splice_read    = generic_file_splice_read,
1896         .unlocked_ioctl = fuse_file_ioctl,
1897         .compat_ioctl   = fuse_file_compat_ioctl,
1898         .poll           = fuse_file_poll,
1899 };
1900
1901 static const struct file_operations fuse_direct_io_file_operations = {
1902         .llseek         = fuse_file_llseek,
1903         .read           = fuse_direct_read,
1904         .write          = fuse_direct_write,
1905         .open           = fuse_open,
1906         .flush          = fuse_flush,
1907         .release        = fuse_release,
1908         .fsync          = fuse_fsync,
1909         .lock           = fuse_file_lock,
1910         .flock          = fuse_file_flock,
1911         .unlocked_ioctl = fuse_file_ioctl,
1912         .compat_ioctl   = fuse_file_compat_ioctl,
1913         .poll           = fuse_file_poll,
1914         /* no mmap and splice_read */
1915 };
1916
1917 static const struct address_space_operations fuse_file_aops  = {
1918         .readpage       = fuse_readpage,
1919         .writepage      = fuse_writepage,
1920         .launder_page   = fuse_launder_page,
1921         .write_begin    = fuse_write_begin,
1922         .write_end      = fuse_write_end,
1923         .readpages      = fuse_readpages,
1924         .set_page_dirty = __set_page_dirty_nobuffers,
1925         .bmap           = fuse_bmap,
1926 };
1927
1928 void fuse_init_file_inode(struct inode *inode)
1929 {
1930         inode->i_fop = &fuse_file_operations;
1931         inode->i_data.a_ops = &fuse_file_aops;
1932 }