fs/fuse/inode.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/file.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/init.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/parser.h>
  19 #include <linux/statfs.h>
  20 #include <linux/random.h>
  21 #include <linux/sched.h>
  22 #include <linux/exportfs.h>
  23
  24 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
  25 MODULE_DESCRIPTION("Filesystem in Userspace");
  26 MODULE_LICENSE("GPL");
  27
  28 static struct kmem_cache *fuse_inode_cachep;
  29 struct list_head fuse_conn_list;
  30 DEFINE_MUTEX(fuse_mutex);
  31
  32 static int set_global_limit(const char *val, struct kernel_param *kp);
  33
  34 unsigned max_user_bgreq;
  35 module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
  36                   &max_user_bgreq, 0644);
  37 __MODULE_PARM_TYPE(max_user_bgreq, "uint");
  38 MODULE_PARM_DESC(max_user_bgreq,
  39  "Global limit for the maximum number of backgrounded requests an "
  40  "unprivileged user can set");
  41
  42 unsigned max_user_congthresh;
  43 module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
  44                   &max_user_congthresh, 0644);
  45 __MODULE_PARM_TYPE(max_user_congthresh, "uint");
  46 MODULE_PARM_DESC(max_user_congthresh,
  47  "Global limit for the maximum congestion threshold an "
  48  "unprivileged user can set");
  49
  50 #define FUSE_SUPER_MAGIC 0x65735546
  51
  52 #define FUSE_DEFAULT_BLKSIZE 512
  53
  54 /** Maximum number of outstanding background requests */
  55 #define FUSE_DEFAULT_MAX_BACKGROUND 12
  56
  57 /** Congestion starts at 75% of maximum */
  58 #define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
  59
  60 struct fuse_mount_data {
  61         int fd;
  62         unsigned rootmode;
  63         kuid_t user_id;
  64         kgid_t group_id;
  65         unsigned fd_present:1;
  66         unsigned rootmode_present:1;
  67         unsigned user_id_present:1;
  68         unsigned group_id_present:1;
  69         unsigned flags;
  70         unsigned max_read;
  71         unsigned blksize;
  72 };
  73
  74 struct fuse_forget_link *fuse_alloc_forget(void)
  75 {
  76         return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL);
  77 }
  78
  79 static struct inode *fuse_alloc_inode(struct super_block *sb)
  80 {
  81         struct inode *inode;
  82         struct fuse_inode *fi;
  83
  84         inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
  85         if (!inode)
  86                 return NULL;
  87
  88         fi = get_fuse_inode(inode);
  89         fi->i_time = 0;
  90         fi->nodeid = 0;
  91         fi->nlookup = 0;
  92         fi->attr_version = 0;
  93         fi->writectr = 0;
  94         fi->orig_ino = 0;
  95         fi->state = 0;
  96         INIT_LIST_HEAD(&fi->write_files);
  97         INIT_LIST_HEAD(&fi->queued_writes);
  98         INIT_LIST_HEAD(&fi->writepages);
  99         init_waitqueue_head(&fi->page_waitq);
 100         fi->forget = fuse_alloc_forget();
 101         if (!fi->forget) {
 102                 kmem_cache_free(fuse_inode_cachep, inode);
 103                 return NULL;
 104         }
 105
 106         return inode;
 107 }
 108
 109 static void fuse_i_callback(struct rcu_head *head)
 110 {
 111         struct inode *inode = container_of(head, struct inode, i_rcu);
 112         kmem_cache_free(fuse_inode_cachep, inode);
 113 }
 114
 115 static void fuse_destroy_inode(struct inode *inode)
 116 {
 117         struct fuse_inode *fi = get_fuse_inode(inode);
 118         BUG_ON(!list_empty(&fi->write_files));
 119         BUG_ON(!list_empty(&fi->queued_writes));
 120         kfree(fi->forget);
 121         call_rcu(&inode->i_rcu, fuse_i_callback);
 122 }
 123
 124 static void fuse_evict_inode(struct inode *inode)
 125 {
 126         truncate_inode_pages(&inode->i_data, 0);
 127         clear_inode(inode);
 128         if (inode->i_sb->s_flags & MS_ACTIVE) {
 129                 struct fuse_conn *fc = get_fuse_conn(inode);
 130                 struct fuse_inode *fi = get_fuse_inode(inode);
 131                 fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
 132                 fi->forget = NULL;
 133         }
 134 }
 135
 136 static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
 137 {
 138         if (*flags & MS_MANDLOCK)
 139                 return -EINVAL;
 140
 141         return 0;
 142 }
 143
 144 /*
 145  * ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
 146  * so that it will fit.
 147  */
 148 static ino_t fuse_squash_ino(u64 ino64)
 149 {
 150         ino_t ino = (ino_t) ino64;
 151         if (sizeof(ino_t) < sizeof(u64))
 152                 ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;
 153         return ino;
 154 }
 155
 156 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 157                                    u64 attr_valid)
 158 {
 159         struct fuse_conn *fc = get_fuse_conn(inode);
 160         struct fuse_inode *fi = get_fuse_inode(inode);
 161
 162         fi->attr_version = ++fc->attr_version;
 163         fi->i_time = attr_valid;
 164
 165         inode->i_ino     = fuse_squash_ino(attr->ino);
 166         inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
 167         set_nlink(inode, attr->nlink);
 168         inode->i_uid     = make_kuid(&init_user_ns, attr->uid);
 169         inode->i_gid     = make_kgid(&init_user_ns, attr->gid);
 170         inode->i_blocks  = attr->blocks;
 171         inode->i_atime.tv_sec   = attr->atime;
 172         inode->i_atime.tv_nsec  = attr->atimensec;
 173         inode->i_mtime.tv_sec   = attr->mtime;
 174         inode->i_mtime.tv_nsec  = attr->mtimensec;
 175         inode->i_ctime.tv_sec   = attr->ctime;
 176         inode->i_ctime.tv_nsec  = attr->ctimensec;
 177
 178         if (attr->blksize != 0)
 179                 inode->i_blkbits = ilog2(attr->blksize);
 180         else
 181                 inode->i_blkbits = inode->i_sb->s_blocksize_bits;
 182
 183         /*
 184          * Don't set the sticky bit in i_mode, unless we want the VFS
 185          * to check permissions.  This prevents failures due to the
 186          * check in may_delete().
 187          */
 188         fi->orig_i_mode = inode->i_mode;
 189         if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
 190                 inode->i_mode &= ~S_ISVTX;
 191
 192         fi->orig_ino = attr->ino;
 193 }
 194
 195 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 196                             u64 attr_valid, u64 attr_version)
 197 {
 198         struct fuse_conn *fc = get_fuse_conn(inode);
 199         struct fuse_inode *fi = get_fuse_inode(inode);
 200         loff_t oldsize;
 201         struct timespec old_mtime;
 202
 203         spin_lock(&fc->lock);
 204         if (attr_version != 0 && fi->attr_version > attr_version) {
 205                 spin_unlock(&fc->lock);
 206                 return;
 207         }
 208
 209         old_mtime = inode->i_mtime;
 210         fuse_change_attributes_common(inode, attr, attr_valid);
 211
 212         oldsize = inode->i_size;
 213         i_size_write(inode, attr->size);
 214         spin_unlock(&fc->lock);
 215
 216         if (S_ISREG(inode->i_mode)) {
 217                 bool inval = false;
 218
 219                 if (oldsize != attr->size) {
 220                         truncate_pagecache(inode, oldsize, attr->size);
 221                         inval = true;
 222                 } else if (fc->auto_inval_data) {
 223                         struct timespec new_mtime = {
 224                                 .tv_sec = attr->mtime,
 225                                 .tv_nsec = attr->mtimensec,
 226                         };
 227
 228                         /*
 229                          * Auto inval mode also checks and invalidates if mtime
 230                          * has changed.
 231                          */
 232                         if (!timespec_equal(&old_mtime, &new_mtime))
 233                                 inval = true;
 234                 }
 235
 236                 if (inval)
 237                         invalidate_inode_pages2(inode->i_mapping);
 238         }
 239 }
 240
 241 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 242 {
 243         inode->i_mode = attr->mode & S_IFMT;
 244         inode->i_size = attr->size;
 245         if (S_ISREG(inode->i_mode)) {
 246                 fuse_init_common(inode);
 247                 fuse_init_file_inode(inode);
 248         } else if (S_ISDIR(inode->i_mode))
 249                 fuse_init_dir(inode);
 250         else if (S_ISLNK(inode->i_mode))
 251                 fuse_init_symlink(inode);
 252         else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 253                  S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 254                 fuse_init_common(inode);
 255                 init_special_inode(inode, inode->i_mode,
 256                                    new_decode_dev(attr->rdev));
 257         } else
 258                 BUG();
 259 }
 260
 261 int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 262 {
 263         u64 nodeid = *(u64 *) _nodeidp;
 264         if (get_node_id(inode) == nodeid)
 265                 return 1;
 266         else
 267                 return 0;
 268 }
 269
 270 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 271 {
 272         u64 nodeid = *(u64 *) _nodeidp;
 273         get_fuse_inode(inode)->nodeid = nodeid;
 274         return 0;
 275 }
 276
 277 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 278                         int generation, struct fuse_attr *attr,
 279                         u64 attr_valid, u64 attr_version)
 280 {
 281         struct inode *inode;
 282         struct fuse_inode *fi;
 283         struct fuse_conn *fc = get_fuse_conn_super(sb);
 284
 285  retry:
 286         inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 287         if (!inode)
 288                 return NULL;
 289
 290         if ((inode->i_state & I_NEW)) {
 291                 inode->i_flags |= S_NOATIME|S_NOCMTIME;
 292                 inode->i_generation = generation;
 293                 inode->i_data.backing_dev_info = &fc->bdi;
 294                 fuse_init_inode(inode, attr);
 295                 unlock_new_inode(inode);
 296         } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 297                 /* Inode has changed type, any I/O on the old should fail */
 298                 make_bad_inode(inode);
 299                 iput(inode);
 300                 goto retry;
 301         }
 302
 303         fi = get_fuse_inode(inode);
 304         spin_lock(&fc->lock);
 305         fi->nlookup++;
 306         spin_unlock(&fc->lock);
 307         fuse_change_attributes(inode, attr, attr_valid, attr_version);
 308
 309         return inode;
 310 }
 311
 312 int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
 313                              loff_t offset, loff_t len)
 314 {
 315         struct inode *inode;
 316         pgoff_t pg_start;
 317         pgoff_t pg_end;
 318
 319         inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
 320         if (!inode)
 321                 return -ENOENT;
 322
 323         fuse_invalidate_attr(inode);
 324         if (offset >= 0) {
 325                 pg_start = offset >> PAGE_CACHE_SHIFT;
 326                 if (len <= 0)
 327                         pg_end = -1;
 328                 else
 329                         pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
 330                 invalidate_inode_pages2_range(inode->i_mapping,
 331                                               pg_start, pg_end);
 332         }
 333         iput(inode);
 334         return 0;
 335 }
 336
 337 static void fuse_umount_begin(struct super_block *sb)
 338 {
 339         fuse_abort_conn(get_fuse_conn_super(sb));
 340 }
 341
 342 static void fuse_send_destroy(struct fuse_conn *fc)
 343 {
 344         struct fuse_req *req = fc->destroy_req;
 345         if (req && fc->conn_init) {
 346                 fc->destroy_req = NULL;
 347                 req->in.h.opcode = FUSE_DESTROY;
 348                 req->force = 1;
 349                 fuse_request_send(fc, req);
 350                 fuse_put_request(fc, req);
 351         }
 352 }
 353
 354 static void fuse_bdi_destroy(struct fuse_conn *fc)
 355 {
 356         if (fc->bdi_initialized)
 357                 bdi_destroy(&fc->bdi);
 358 }
 359
 360 void fuse_conn_kill(struct fuse_conn *fc)
 361 {
 362         spin_lock(&fc->lock);
 363         fc->connected = 0;
 364         fc->blocked = 0;
 365         spin_unlock(&fc->lock);
 366         /* Flush all readers on this fs */
 367         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 368         wake_up_all(&fc->waitq);
 369         wake_up_all(&fc->blocked_waitq);
 370         wake_up_all(&fc->reserved_req_waitq);
 371 }
 372 EXPORT_SYMBOL_GPL(fuse_conn_kill);
 373
 374 static void fuse_put_super(struct super_block *sb)
 375 {
 376         struct fuse_conn *fc = get_fuse_conn_super(sb);
 377
 378         fuse_send_destroy(fc);
 379
 380         fuse_conn_kill(fc);
 381         mutex_lock(&fuse_mutex);
 382         list_del(&fc->entry);
 383         fuse_ctl_remove_conn(fc);
 384         mutex_unlock(&fuse_mutex);
 385         fuse_bdi_destroy(fc);
 386
 387         fuse_conn_put(fc);
 388 }
 389
 390 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
 391 {
 392         stbuf->f_type    = FUSE_SUPER_MAGIC;
 393         stbuf->f_bsize   = attr->bsize;
 394         stbuf->f_frsize  = attr->frsize;
 395         stbuf->f_blocks  = attr->blocks;
 396         stbuf->f_bfree   = attr->bfree;
 397         stbuf->f_bavail  = attr->bavail;
 398         stbuf->f_files   = attr->files;
 399         stbuf->f_ffree   = attr->ffree;
 400         stbuf->f_namelen = attr->namelen;
 401         /* fsid is left zero */
 402 }
 403
 404 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 405 {
 406         struct super_block *sb = dentry->d_sb;
 407         struct fuse_conn *fc = get_fuse_conn_super(sb);
 408         struct fuse_req *req;
 409         struct fuse_statfs_out outarg;
 410         int err;
 411
 412         if (!fuse_allow_current_process(fc)) {
 413                 buf->f_type = FUSE_SUPER_MAGIC;
 414                 return 0;
 415         }
 416
 417         req = fuse_get_req_nopages(fc);
 418         if (IS_ERR(req))
 419                 return PTR_ERR(req);
 420
 421         memset(&outarg, 0, sizeof(outarg));
 422         req->in.numargs = 0;
 423         req->in.h.opcode = FUSE_STATFS;
 424         req->in.h.nodeid = get_node_id(dentry->d_inode);
 425         req->out.numargs = 1;
 426         req->out.args[0].size =
 427                 fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
 428         req->out.args[0].value = &outarg;
 429         fuse_request_send(fc, req);
 430         err = req->out.h.error;
 431         if (!err)
 432                 convert_fuse_statfs(buf, &outarg.st);
 433         fuse_put_request(fc, req);
 434         return err;
 435 }
 436
 437 enum {
 438         OPT_FD,
 439         OPT_ROOTMODE,
 440         OPT_USER_ID,
 441         OPT_GROUP_ID,
 442         OPT_DEFAULT_PERMISSIONS,
 443         OPT_ALLOW_OTHER,
 444         OPT_MAX_READ,
 445         OPT_BLKSIZE,
 446         OPT_ERR
 447 };
 448
 449 static const match_table_t tokens = {
 450         {OPT_FD,                        "fd=%u"},
 451         {OPT_ROOTMODE,                  "rootmode=%o"},
 452         {OPT_USER_ID,                   "user_id=%u"},
 453         {OPT_GROUP_ID,                  "group_id=%u"},
 454         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
 455         {OPT_ALLOW_OTHER,               "allow_other"},
 456         {OPT_MAX_READ,                  "max_read=%u"},
 457         {OPT_BLKSIZE,                   "blksize=%u"},
 458         {OPT_ERR,                       NULL}
 459 };
 460
 461 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
 462 {
 463         char *p;
 464         memset(d, 0, sizeof(struct fuse_mount_data));
 465         d->max_read = ~0;
 466         d->blksize = FUSE_DEFAULT_BLKSIZE;
 467
 468         while ((p = strsep(&opt, ",")) != NULL) {
 469                 int token;
 470                 int value;
 471                 substring_t args[MAX_OPT_ARGS];
 472                 if (!*p)
 473                         continue;
 474
 475                 token = match_token(p, tokens, args);
 476                 switch (token) {
 477                 case OPT_FD:
 478                         if (match_int(&args[0], &value))
 479                                 return 0;
 480                         d->fd = value;
 481                         d->fd_present = 1;
 482                         break;
 483
 484                 case OPT_ROOTMODE:
 485                         if (match_octal(&args[0], &value))
 486                                 return 0;
 487                         if (!fuse_valid_type(value))
 488                                 return 0;
 489                         d->rootmode = value;
 490                         d->rootmode_present = 1;
 491                         break;
 492
 493                 case OPT_USER_ID:
 494                         if (match_int(&args[0], &value))
 495                                 return 0;
 496                         d->user_id = make_kuid(current_user_ns(), value);
 497                         if (!uid_valid(d->user_id))
 498                                 return 0;
 499                         d->user_id_present = 1;
 500                         break;
 501
 502                 case OPT_GROUP_ID:
 503                         if (match_int(&args[0], &value))
 504                                 return 0;
 505                         d->group_id = make_kgid(current_user_ns(), value);
 506                         if (!gid_valid(d->group_id))
 507                                 return 0;
 508                         d->group_id_present = 1;
 509                         break;
 510
 511                 case OPT_DEFAULT_PERMISSIONS:
 512                         d->flags |= FUSE_DEFAULT_PERMISSIONS;
 513                         break;
 514
 515                 case OPT_ALLOW_OTHER:
 516                         d->flags |= FUSE_ALLOW_OTHER;
 517                         break;
 518
 519                 case OPT_MAX_READ:
 520                         if (match_int(&args[0], &value))
 521                                 return 0;
 522                         d->max_read = value;
 523                         break;
 524
 525                 case OPT_BLKSIZE:
 526                         if (!is_bdev || match_int(&args[0], &value))
 527                                 return 0;
 528                         d->blksize = value;
 529                         break;
 530
 531                 default:
 532                         return 0;
 533                 }
 534         }
 535
 536         if (!d->fd_present || !d->rootmode_present ||
 537             !d->user_id_present || !d->group_id_present)
 538                 return 0;
 539
 540         return 1;
 541 }
 542
 543 static int fuse_show_options(struct seq_file *m, struct dentry *root)
 544 {
 545         struct super_block *sb = root->d_sb;
 546         struct fuse_conn *fc = get_fuse_conn_super(sb);
 547
 548         seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id));
 549         seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id));
 550         if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
 551                 seq_puts(m, ",default_permissions");
 552         if (fc->flags & FUSE_ALLOW_OTHER)
 553                 seq_puts(m, ",allow_other");
 554         if (fc->max_read != ~0)
 555                 seq_printf(m, ",max_read=%u", fc->max_read);
 556         if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
 557                 seq_printf(m, ",blksize=%lu", sb->s_blocksize);
 558         return 0;
 559 }
 560
 561 void fuse_conn_init(struct fuse_conn *fc)
 562 {
 563         memset(fc, 0, sizeof(*fc));
 564         spin_lock_init(&fc->lock);
 565         mutex_init(&fc->inst_mutex);
 566         init_rwsem(&fc->killsb);
 567         atomic_set(&fc->count, 1);
 568         init_waitqueue_head(&fc->waitq);
 569         init_waitqueue_head(&fc->blocked_waitq);
 570         init_waitqueue_head(&fc->reserved_req_waitq);
 571         INIT_LIST_HEAD(&fc->pending);
 572         INIT_LIST_HEAD(&fc->processing);
 573         INIT_LIST_HEAD(&fc->io);
 574         INIT_LIST_HEAD(&fc->interrupts);
 575         INIT_LIST_HEAD(&fc->bg_queue);
 576         INIT_LIST_HEAD(&fc->entry);
 577         fc->forget_list_tail = &fc->forget_list_head;
 578         atomic_set(&fc->num_waiting, 0);
 579         fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
 580         fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
 581         fc->khctr = 0;
 582         fc->polled_files = RB_ROOT;
 583         fc->reqctr = 0;
 584         fc->blocked = 1;
 585         fc->attr_version = 1;
 586         get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 587 }
 588 EXPORT_SYMBOL_GPL(fuse_conn_init);
 589
 590 void fuse_conn_put(struct fuse_conn *fc)
 591 {
 592         if (atomic_dec_and_test(&fc->count)) {
 593                 if (fc->destroy_req)
 594                         fuse_request_free(fc->destroy_req);
 595                 mutex_destroy(&fc->inst_mutex);
 596                 fc->release(fc);
 597         }
 598 }
 599 EXPORT_SYMBOL_GPL(fuse_conn_put);
 600
 601 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
 602 {
 603         atomic_inc(&fc->count);
 604         return fc;
 605 }
 606 EXPORT_SYMBOL_GPL(fuse_conn_get);
 607
 608 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
 609 {
 610         struct fuse_attr attr;
 611         memset(&attr, 0, sizeof(attr));
 612
 613         attr.mode = mode;
 614         attr.ino = FUSE_ROOT_ID;
 615         attr.nlink = 1;
 616         return fuse_iget(sb, 1, 0, &attr, 0, 0);
 617 }
 618
 619 struct fuse_inode_handle {
 620         u64 nodeid;
 621         u32 generation;
 622 };
 623
 624 static struct dentry *fuse_get_dentry(struct super_block *sb,
 625                                       struct fuse_inode_handle *handle)
 626 {
 627         struct fuse_conn *fc = get_fuse_conn_super(sb);
 628         struct inode *inode;
 629         struct dentry *entry;
 630         int err = -ESTALE;
 631
 632         if (handle->nodeid == 0)
 633                 goto out_err;
 634
 635         inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
 636         if (!inode) {
 637                 struct fuse_entry_out outarg;
 638                 struct qstr name;
 639
 640                 if (!fc->export_support)
 641                         goto out_err;
 642
 643                 name.len = 1;
 644                 name.name = ".";
 645                 err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
 646                                        &inode);
 647                 if (err && err != -ENOENT)
 648                         goto out_err;
 649                 if (err || !inode) {
 650                         err = -ESTALE;
 651                         goto out_err;
 652                 }
 653                 err = -EIO;
 654                 if (get_node_id(inode) != handle->nodeid)
 655                         goto out_iput;
 656         }
 657         err = -ESTALE;
 658         if (inode->i_generation != handle->generation)
 659                 goto out_iput;
 660
 661         entry = d_obtain_alias(inode);
 662         if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
 663                 fuse_invalidate_entry_cache(entry);
 664
 665         return entry;
 666
 667  out_iput:
 668         iput(inode);
 669  out_err:
 670         return ERR_PTR(err);
 671 }
 672
 673 static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
 674                            struct inode *parent)
 675 {
 676         int len = parent ? 6 : 3;
 677         u64 nodeid;
 678         u32 generation;
 679
 680         if (*max_len < len) {
 681                 *max_len = len;
 682                 return  FILEID_INVALID;
 683         }
 684
 685         nodeid = get_fuse_inode(inode)->nodeid;
 686         generation = inode->i_generation;
 687
 688         fh[0] = (u32)(nodeid >> 32);
 689         fh[1] = (u32)(nodeid & 0xffffffff);
 690         fh[2] = generation;
 691
 692         if (parent) {
 693                 nodeid = get_fuse_inode(parent)->nodeid;
 694                 generation = parent->i_generation;
 695
 696                 fh[3] = (u32)(nodeid >> 32);
 697                 fh[4] = (u32)(nodeid & 0xffffffff);
 698                 fh[5] = generation;
 699         }
 700
 701         *max_len = len;
 702         return parent ? 0x82 : 0x81;
 703 }
 704
 705 static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
 706                 struct fid *fid, int fh_len, int fh_type)
 707 {
 708         struct fuse_inode_handle handle;
 709
 710         if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
 711                 return NULL;
 712
 713         handle.nodeid = (u64) fid->raw[0] << 32;
 714         handle.nodeid |= (u64) fid->raw[1];
 715         handle.generation = fid->raw[2];
 716         return fuse_get_dentry(sb, &handle);
 717 }
 718
 719 static struct dentry *fuse_fh_to_parent(struct super_block *sb,
 720                 struct fid *fid, int fh_len, int fh_type)
 721 {
 722         struct fuse_inode_handle parent;
 723
 724         if (fh_type != 0x82 || fh_len < 6)
 725                 return NULL;
 726
 727         parent.nodeid = (u64) fid->raw[3] << 32;
 728         parent.nodeid |= (u64) fid->raw[4];
 729         parent.generation = fid->raw[5];
 730         return fuse_get_dentry(sb, &parent);
 731 }
 732
 733 static struct dentry *fuse_get_parent(struct dentry *child)
 734 {
 735         struct inode *child_inode = child->d_inode;
 736         struct fuse_conn *fc = get_fuse_conn(child_inode);
 737         struct inode *inode;
 738         struct dentry *parent;
 739         struct fuse_entry_out outarg;
 740         struct qstr name;
 741         int err;
 742
 743         if (!fc->export_support)
 744                 return ERR_PTR(-ESTALE);
 745
 746         name.len = 2;
 747         name.name = "..";
 748         err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
 749                                &name, &outarg, &inode);
 750         if (err) {
 751                 if (err == -ENOENT)
 752                         return ERR_PTR(-ESTALE);
 753                 return ERR_PTR(err);
 754         }
 755
 756         parent = d_obtain_alias(inode);
 757         if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
 758                 fuse_invalidate_entry_cache(parent);
 759
 760         return parent;
 761 }
 762
 763 static const struct export_operations fuse_export_operations = {
 764         .fh_to_dentry   = fuse_fh_to_dentry,
 765         .fh_to_parent   = fuse_fh_to_parent,
 766         .encode_fh      = fuse_encode_fh,
 767         .get_parent     = fuse_get_parent,
 768 };
 769
 770 static const struct super_operations fuse_super_operations = {
 771         .alloc_inode    = fuse_alloc_inode,
 772         .destroy_inode  = fuse_destroy_inode,
 773         .evict_inode    = fuse_evict_inode,
 774         .drop_inode     = generic_delete_inode,
 775         .remount_fs     = fuse_remount_fs,
 776         .put_super      = fuse_put_super,
 777         .umount_begin   = fuse_umount_begin,
 778         .statfs         = fuse_statfs,
 779         .show_options   = fuse_show_options,
 780 };
 781
 782 static void sanitize_global_limit(unsigned *limit)
 783 {
 784         if (*limit == 0)
 785                 *limit = ((num_physpages << PAGE_SHIFT) >> 13) /
 786                          sizeof(struct fuse_req);
 787
 788         if (*limit >= 1 << 16)
 789                 *limit = (1 << 16) - 1;
 790 }
 791
 792 static int set_global_limit(const char *val, struct kernel_param *kp)
 793 {
 794         int rv;
 795
 796         rv = param_set_uint(val, kp);
 797         if (rv)
 798                 return rv;
 799
 800         sanitize_global_limit((unsigned *)kp->arg);
 801
 802         return 0;
 803 }
 804
 805 static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 806 {
 807         int cap_sys_admin = capable(CAP_SYS_ADMIN);
 808
 809         if (arg->minor < 13)
 810                 return;
 811
 812         sanitize_global_limit(&max_user_bgreq);
 813         sanitize_global_limit(&max_user_congthresh);
 814
 815         if (arg->max_background) {
 816                 fc->max_background = arg->max_background;
 817
 818                 if (!cap_sys_admin && fc->max_background > max_user_bgreq)
 819                         fc->max_background = max_user_bgreq;
 820         }
 821         if (arg->congestion_threshold) {
 822                 fc->congestion_threshold = arg->congestion_threshold;
 823
 824                 if (!cap_sys_admin &&
 825                     fc->congestion_threshold > max_user_congthresh)
 826                         fc->congestion_threshold = max_user_congthresh;
 827         }
 828 }
 829
 830 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 831 {
 832         struct fuse_init_out *arg = &req->misc.init_out;
 833
 834         if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
 835                 fc->conn_error = 1;
 836         else {
 837                 unsigned long ra_pages;
 838
 839                 process_init_limits(fc, arg);
 840
 841                 if (arg->minor >= 6) {
 842                         ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
 843                         if (arg->flags & FUSE_ASYNC_READ)
 844                                 fc->async_read = 1;
 845                         if (!(arg->flags & FUSE_POSIX_LOCKS))
 846                                 fc->no_lock = 1;
 847                         if (arg->minor >= 17) {
 848                                 if (!(arg->flags & FUSE_FLOCK_LOCKS))
 849                                         fc->no_flock = 1;
 850                         } else {
 851                                 if (!(arg->flags & FUSE_POSIX_LOCKS))
 852                                         fc->no_flock = 1;
 853                         }
 854                         if (arg->flags & FUSE_ATOMIC_O_TRUNC)
 855                                 fc->atomic_o_trunc = 1;
 856                         if (arg->minor >= 9) {
 857                                 /* LOOKUP has dependency on proto version */
 858                                 if (arg->flags & FUSE_EXPORT_SUPPORT)
 859                                         fc->export_support = 1;
 860                         }
 861                         if (arg->flags & FUSE_BIG_WRITES)
 862                                 fc->big_writes = 1;
 863                         if (arg->flags & FUSE_DONT_MASK)
 864                                 fc->dont_mask = 1;
 865                         if (arg->flags & FUSE_AUTO_INVAL_DATA)
 866                                 fc->auto_inval_data = 1;
 867                         if (arg->flags & FUSE_DO_READDIRPLUS)
 868                                 fc->do_readdirplus = 1;
 869                         if (arg->flags & FUSE_READDIRPLUS_AUTO)
 870                                 fc->readdirplus_auto = 1;
 871                 } else {
 872                         ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 873                         fc->no_lock = 1;
 874                         fc->no_flock = 1;
 875                 }
 876
 877                 fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
 878                 fc->minor = arg->minor;
 879                 fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
 880                 fc->max_write = max_t(unsigned, 4096, fc->max_write);
 881                 fc->conn_init = 1;
 882         }
 883         fc->blocked = 0;
 884         wake_up_all(&fc->blocked_waitq);
 885 }
 886
 887 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
 888 {
 889         struct fuse_init_in *arg = &req->misc.init_in;
 890
 891         arg->major = FUSE_KERNEL_VERSION;
 892         arg->minor = FUSE_KERNEL_MINOR_VERSION;
 893         arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
 894         arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
 895                 FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
 896                 FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
 897                 FUSE_FLOCK_LOCKS | FUSE_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
 898                 FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO;
 899         req->in.h.opcode = FUSE_INIT;
 900         req->in.numargs = 1;
 901         req->in.args[0].size = sizeof(*arg);
 902         req->in.args[0].value = arg;
 903         req->out.numargs = 1;
 904         /* Variable length argument used for backward compatibility
 905            with interface version < 7.5.  Rest of init_out is zeroed
 906            by do_get_request(), so a short reply is not a problem */
 907         req->out.argvar = 1;
 908         req->out.args[0].size = sizeof(struct fuse_init_out);
 909         req->out.args[0].value = &req->misc.init_out;
 910         req->end = process_init_reply;
 911         fuse_request_send_background(fc, req);
 912 }
 913
 914 static void fuse_free_conn(struct fuse_conn *fc)
 915 {
 916         kfree(fc);
 917 }
 918
 919 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
 920 {
 921         int err;
 922
 923         fc->bdi.name = "fuse";
 924         fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 925         /* fuse does it's own writeback accounting */
 926         fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB;
 927
 928         err = bdi_init(&fc->bdi);
 929         if (err)
 930                 return err;
 931
 932         fc->bdi_initialized = 1;
 933
 934         if (sb->s_bdev) {
 935                 err =  bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",
 936                                     MAJOR(fc->dev), MINOR(fc->dev));
 937         } else {
 938                 err = bdi_register_dev(&fc->bdi, fc->dev);
 939         }
 940
 941         if (err)
 942                 return err;
 943
 944         /*
 945          * For a single fuse filesystem use max 1% of dirty +
 946          * writeback threshold.
 947          *
 948          * This gives about 1M of write buffer for memory maps on a
 949          * machine with 1G and 10% dirty_ratio, which should be more
 950          * than enough.
 951          *
 952          * Privileged users can raise it by writing to
 953          *
 954          *    /sys/class/bdi/<bdi>/max_ratio
 955          */
 956         bdi_set_max_ratio(&fc->bdi, 1);
 957
 958         return 0;
 959 }
 960
 961 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 962 {
 963         struct fuse_conn *fc;
 964         struct inode *root;
 965         struct fuse_mount_data d;
 966         struct file *file;
 967         struct dentry *root_dentry;
 968         struct fuse_req *init_req;
 969         int err;
 970         int is_bdev = sb->s_bdev != NULL;
 971
 972         err = -EINVAL;
 973         if (sb->s_flags & MS_MANDLOCK)
 974                 goto err;
 975
 976         sb->s_flags &= ~MS_NOSEC;
 977
 978         if (!parse_fuse_opt((char *) data, &d, is_bdev))
 979                 goto err;
 980
 981         if (is_bdev) {
 982 #ifdef CONFIG_BLOCK
 983                 err = -EINVAL;
 984                 if (!sb_set_blocksize(sb, d.blksize))
 985                         goto err;
 986 #endif
 987         } else {
 988                 sb->s_blocksize = PAGE_CACHE_SIZE;
 989                 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 990         }
 991         sb->s_magic = FUSE_SUPER_MAGIC;
 992         sb->s_op = &fuse_super_operations;
 993         sb->s_maxbytes = MAX_LFS_FILESIZE;
 994         sb->s_time_gran = 1;
 995         sb->s_export_op = &fuse_export_operations;
 996
 997         file = fget(d.fd);
 998         err = -EINVAL;
 999         if (!file)
1000                 goto err;
1001
1002         if ((file->f_op != &fuse_dev_operations) ||
1003             (file->f_cred->user_ns != &init_user_ns))
1004                 goto err_fput;
1005
1006         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1007         err = -ENOMEM;
1008         if (!fc)
1009                 goto err_fput;
1010
1011         fuse_conn_init(fc);
1012
1013         fc->dev = sb->s_dev;
1014         fc->sb = sb;
1015         err = fuse_bdi_init(fc, sb);
1016         if (err)
1017                 goto err_put_conn;
1018
1019         sb->s_bdi = &fc->bdi;
1020
1021         /* Handle umasking inside the fuse code */
1022         if (sb->s_flags & MS_POSIXACL)
1023                 fc->dont_mask = 1;
1024         sb->s_flags |= MS_POSIXACL;
1025
1026         fc->release = fuse_free_conn;
1027         fc->flags = d.flags;
1028         fc->user_id = d.user_id;
1029         fc->group_id = d.group_id;
1030         fc->max_read = max_t(unsigned, 4096, d.max_read);
1031
1032         /* Used by get_root_inode() */
1033         sb->s_fs_info = fc;
1034
1035         err = -ENOMEM;
1036         root = fuse_get_root_inode(sb, d.rootmode);
1037         root_dentry = d_make_root(root);
1038         if (!root_dentry)
1039                 goto err_put_conn;
1040         /* only now - we want root dentry with NULL ->d_op */
1041         sb->s_d_op = &fuse_dentry_operations;
1042
1043         init_req = fuse_request_alloc(0);
1044         if (!init_req)
1045                 goto err_put_root;
1046
1047         if (is_bdev) {
1048                 fc->destroy_req = fuse_request_alloc(0);
1049                 if (!fc->destroy_req)
1050                         goto err_free_init_req;
1051         }
1052
1053         mutex_lock(&fuse_mutex);
1054         err = -EINVAL;
1055         if (file->private_data)
1056                 goto err_unlock;
1057
1058         err = fuse_ctl_add_conn(fc);
1059         if (err)
1060                 goto err_unlock;
1061
1062         list_add_tail(&fc->entry, &fuse_conn_list);
1063         sb->s_root = root_dentry;
1064         fc->connected = 1;
1065         file->private_data = fuse_conn_get(fc);
1066         mutex_unlock(&fuse_mutex);
1067         /*
1068          * atomic_dec_and_test() in fput() provides the necessary
1069          * memory barrier for file->private_data to be visible on all
1070          * CPUs after this
1071          */
1072         fput(file);
1073
1074         fuse_send_init(fc, init_req);
1075
1076         return 0;
1077
1078  err_unlock:
1079         mutex_unlock(&fuse_mutex);
1080  err_free_init_req:
1081         fuse_request_free(init_req);
1082  err_put_root:
1083         dput(root_dentry);
1084  err_put_conn:
1085         fuse_bdi_destroy(fc);
1086         fuse_conn_put(fc);
1087  err_fput:
1088         fput(file);
1089  err:
1090         return err;
1091 }
1092
1093 static struct dentry *fuse_mount(struct file_system_type *fs_type,
1094                        int flags, const char *dev_name,
1095                        void *raw_data)
1096 {
1097         return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
1098 }
1099
1100 static void fuse_kill_sb_anon(struct super_block *sb)
1101 {
1102         struct fuse_conn *fc = get_fuse_conn_super(sb);
1103
1104         if (fc) {
1105                 down_write(&fc->killsb);
1106                 fc->sb = NULL;
1107                 up_write(&fc->killsb);
1108         }
1109
1110         kill_anon_super(sb);
1111 }
1112
1113 static struct file_system_type fuse_fs_type = {
1114         .owner          = THIS_MODULE,
1115         .name           = "fuse",
1116         .fs_flags       = FS_HAS_SUBTYPE,
1117         .mount          = fuse_mount,
1118         .kill_sb        = fuse_kill_sb_anon,
1119 };
1120
1121 #ifdef CONFIG_BLOCK
1122 static struct dentry *fuse_mount_blk(struct file_system_type *fs_type,
1123                            int flags, const char *dev_name,
1124                            void *raw_data)
1125 {
1126         return mount_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super);
1127 }
1128
1129 static void fuse_kill_sb_blk(struct super_block *sb)
1130 {
1131         struct fuse_conn *fc = get_fuse_conn_super(sb);
1132
1133         if (fc) {
1134                 down_write(&fc->killsb);
1135                 fc->sb = NULL;
1136                 up_write(&fc->killsb);
1137         }
1138
1139         kill_block_super(sb);
1140 }
1141
1142 static struct file_system_type fuseblk_fs_type = {
1143         .owner          = THIS_MODULE,
1144         .name           = "fuseblk",
1145         .mount          = fuse_mount_blk,
1146         .kill_sb        = fuse_kill_sb_blk,
1147         .fs_flags       = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1148 };
1149
1150 static inline int register_fuseblk(void)
1151 {
1152         return register_filesystem(&fuseblk_fs_type);
1153 }
1154
1155 static inline void unregister_fuseblk(void)
1156 {
1157         unregister_filesystem(&fuseblk_fs_type);
1158 }
1159 #else
1160 static inline int register_fuseblk(void)
1161 {
1162         return 0;
1163 }
1164
1165 static inline void unregister_fuseblk(void)
1166 {
1167 }
1168 #endif
1169
1170 static void fuse_inode_init_once(void *foo)
1171 {
1172         struct inode *inode = foo;
1173
1174         inode_init_once(inode);
1175 }
1176
1177 static int __init fuse_fs_init(void)
1178 {
1179         int err;
1180
1181         fuse_inode_cachep = kmem_cache_create("fuse_inode",
1182                                               sizeof(struct fuse_inode),
1183                                               0, SLAB_HWCACHE_ALIGN,
1184                                               fuse_inode_init_once);
1185         err = -ENOMEM;
1186         if (!fuse_inode_cachep)
1187                 goto out;
1188
1189         err = register_fuseblk();
1190         if (err)
1191                 goto out2;
1192
1193         err = register_filesystem(&fuse_fs_type);
1194         if (err)
1195                 goto out3;
1196
1197         return 0;
1198
1199  out3:
1200         unregister_fuseblk();
1201  out2:
1202         kmem_cache_destroy(fuse_inode_cachep);
1203  out:
1204         return err;
1205 }
1206
1207 static void fuse_fs_cleanup(void)
1208 {
1209         unregister_filesystem(&fuse_fs_type);
1210         unregister_fuseblk();
1211
1212         /*
1213          * Make sure all delayed rcu free inodes are flushed before we
1214          * destroy cache.
1215          */
1216         rcu_barrier();
1217         kmem_cache_destroy(fuse_inode_cachep);
1218 }
1219
1220 static struct kobject *fuse_kobj;
1221 static struct kobject *connections_kobj;
1222
1223 static int fuse_sysfs_init(void)
1224 {
1225         int err;
1226
1227         fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1228         if (!fuse_kobj) {
1229                 err = -ENOMEM;
1230                 goto out_err;
1231         }
1232
1233         connections_kobj = kobject_create_and_add("connections", fuse_kobj);
1234         if (!connections_kobj) {
1235                 err = -ENOMEM;
1236                 goto out_fuse_unregister;
1237         }
1238
1239         return 0;
1240
1241  out_fuse_unregister:
1242         kobject_put(fuse_kobj);
1243  out_err:
1244         return err;
1245 }
1246
1247 static void fuse_sysfs_cleanup(void)
1248 {
1249         kobject_put(connections_kobj);
1250         kobject_put(fuse_kobj);
1251 }
1252
1253 static int __init fuse_init(void)
1254 {
1255         int res;
1256
1257         printk(KERN_INFO "fuse init (API version %i.%i)\n",
1258                FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1259
1260         INIT_LIST_HEAD(&fuse_conn_list);
1261         res = fuse_fs_init();
1262         if (res)
1263                 goto err;
1264
1265         res = fuse_dev_init();
1266         if (res)
1267                 goto err_fs_cleanup;
1268
1269         res = fuse_sysfs_init();
1270         if (res)
1271                 goto err_dev_cleanup;
1272
1273         res = fuse_ctl_init();
1274         if (res)
1275                 goto err_sysfs_cleanup;
1276
1277         sanitize_global_limit(&max_user_bgreq);
1278         sanitize_global_limit(&max_user_congthresh);
1279
1280         return 0;
1281
1282  err_sysfs_cleanup:
1283         fuse_sysfs_cleanup();
1284  err_dev_cleanup:
1285         fuse_dev_cleanup();
1286  err_fs_cleanup:
1287         fuse_fs_cleanup();
1288  err:
1289         return res;
1290 }
1291
1292 static void __exit fuse_exit(void)
1293 {
1294         printk(KERN_DEBUG "fuse exit\n");
1295
1296         fuse_ctl_cleanup();
1297         fuse_sysfs_cleanup();
1298         fuse_fs_cleanup();
1299         fuse_dev_cleanup();
1300 }
1301
1302 module_init(fuse_init);
1303 module_exit(fuse_exit);