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             test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
 206                 spin_unlock(&fc->lock);
 207                 return;
 208         }
 209
 210         old_mtime = inode->i_mtime;
 211         fuse_change_attributes_common(inode, attr, attr_valid);
 212
 213         oldsize = inode->i_size;
 214         i_size_write(inode, attr->size);
 215         spin_unlock(&fc->lock);
 216
 217         if (S_ISREG(inode->i_mode)) {
 218                 bool inval = false;
 219
 220                 if (oldsize != attr->size) {
 221                         truncate_pagecache(inode, oldsize, attr->size);
 222                         inval = true;
 223                 } else if (fc->auto_inval_data) {
 224                         struct timespec new_mtime = {
 225                                 .tv_sec = attr->mtime,
 226                                 .tv_nsec = attr->mtimensec,
 227                         };
 228
 229                         /*
 230                          * Auto inval mode also checks and invalidates if mtime
 231                          * has changed.
 232                          */
 233                         if (!timespec_equal(&old_mtime, &new_mtime))
 234                                 inval = true;
 235                 }
 236
 237                 if (inval)
 238                         invalidate_inode_pages2(inode->i_mapping);
 239         }
 240 }
 241
 242 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 243 {
 244         inode->i_mode = attr->mode & S_IFMT;
 245         inode->i_size = attr->size;
 246         if (S_ISREG(inode->i_mode)) {
 247                 fuse_init_common(inode);
 248                 fuse_init_file_inode(inode);
 249         } else if (S_ISDIR(inode->i_mode))
 250                 fuse_init_dir(inode);
 251         else if (S_ISLNK(inode->i_mode))
 252                 fuse_init_symlink(inode);
 253         else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 254                  S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 255                 fuse_init_common(inode);
 256                 init_special_inode(inode, inode->i_mode,
 257                                    new_decode_dev(attr->rdev));
 258         } else
 259                 BUG();
 260 }
 261
 262 int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 263 {
 264         u64 nodeid = *(u64 *) _nodeidp;
 265         if (get_node_id(inode) == nodeid)
 266                 return 1;
 267         else
 268                 return 0;
 269 }
 270
 271 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 272 {
 273         u64 nodeid = *(u64 *) _nodeidp;
 274         get_fuse_inode(inode)->nodeid = nodeid;
 275         return 0;
 276 }
 277
 278 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 279                         int generation, struct fuse_attr *attr,
 280                         u64 attr_valid, u64 attr_version)
 281 {
 282         struct inode *inode;
 283         struct fuse_inode *fi;
 284         struct fuse_conn *fc = get_fuse_conn_super(sb);
 285
 286  retry:
 287         inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 288         if (!inode)
 289                 return NULL;
 290
 291         if ((inode->i_state & I_NEW)) {
 292                 inode->i_flags |= S_NOATIME|S_NOCMTIME;
 293                 inode->i_generation = generation;
 294                 inode->i_data.backing_dev_info = &fc->bdi;
 295                 fuse_init_inode(inode, attr);
 296                 unlock_new_inode(inode);
 297         } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 298                 /* Inode has changed type, any I/O on the old should fail */
 299                 make_bad_inode(inode);
 300                 iput(inode);
 301                 goto retry;
 302         }
 303
 304         fi = get_fuse_inode(inode);
 305         spin_lock(&fc->lock);
 306         fi->nlookup++;
 307         spin_unlock(&fc->lock);
 308         fuse_change_attributes(inode, attr, attr_valid, attr_version);
 309
 310         return inode;
 311 }
 312
 313 int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
 314                              loff_t offset, loff_t len)
 315 {
 316         struct inode *inode;
 317         pgoff_t pg_start;
 318         pgoff_t pg_end;
 319
 320         inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
 321         if (!inode)
 322                 return -ENOENT;
 323
 324         fuse_invalidate_attr(inode);
 325         if (offset >= 0) {
 326                 pg_start = offset >> PAGE_CACHE_SHIFT;
 327                 if (len <= 0)
 328                         pg_end = -1;
 329                 else
 330                         pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
 331                 invalidate_inode_pages2_range(inode->i_mapping,
 332                                               pg_start, pg_end);
 333         }
 334         iput(inode);
 335         return 0;
 336 }
 337
 338 static void fuse_umount_begin(struct super_block *sb)
 339 {
 340         fuse_abort_conn(get_fuse_conn_super(sb));
 341 }
 342
 343 static void fuse_send_destroy(struct fuse_conn *fc)
 344 {
 345         struct fuse_req *req = fc->destroy_req;
 346         if (req && fc->conn_init) {
 347                 fc->destroy_req = NULL;
 348                 req->in.h.opcode = FUSE_DESTROY;
 349                 req->force = 1;
 350                 req->background = 0;
 351                 fuse_request_send(fc, req);
 352                 fuse_put_request(fc, req);
 353         }
 354 }
 355
 356 static void fuse_bdi_destroy(struct fuse_conn *fc)
 357 {
 358         if (fc->bdi_initialized)
 359                 bdi_destroy(&fc->bdi);
 360 }
 361
 362 void fuse_conn_kill(struct fuse_conn *fc)
 363 {
 364         spin_lock(&fc->lock);
 365         fc->connected = 0;
 366         fc->blocked = 0;
 367         fc->initialized = 1;
 368         spin_unlock(&fc->lock);
 369         /* Flush all readers on this fs */
 370         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 371         wake_up_all(&fc->waitq);
 372         wake_up_all(&fc->blocked_waitq);
 373         wake_up_all(&fc->reserved_req_waitq);
 374 }
 375 EXPORT_SYMBOL_GPL(fuse_conn_kill);
 376
 377 static void fuse_put_super(struct super_block *sb)
 378 {
 379         struct fuse_conn *fc = get_fuse_conn_super(sb);
 380
 381         fuse_send_destroy(fc);
 382
 383         fuse_conn_kill(fc);
 384         mutex_lock(&fuse_mutex);
 385         list_del(&fc->entry);
 386         fuse_ctl_remove_conn(fc);
 387         mutex_unlock(&fuse_mutex);
 388         fuse_bdi_destroy(fc);
 389
 390         fuse_conn_put(fc);
 391 }
 392
 393 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
 394 {
 395         stbuf->f_type    = FUSE_SUPER_MAGIC;
 396         stbuf->f_bsize   = attr->bsize;
 397         stbuf->f_frsize  = attr->frsize;
 398         stbuf->f_blocks  = attr->blocks;
 399         stbuf->f_bfree   = attr->bfree;
 400         stbuf->f_bavail  = attr->bavail;
 401         stbuf->f_files   = attr->files;
 402         stbuf->f_ffree   = attr->ffree;
 403         stbuf->f_namelen = attr->namelen;
 404         /* fsid is left zero */
 405 }
 406
 407 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 408 {
 409         struct super_block *sb = dentry->d_sb;
 410         struct fuse_conn *fc = get_fuse_conn_super(sb);
 411         struct fuse_req *req;
 412         struct fuse_statfs_out outarg;
 413         int err;
 414
 415         if (!fuse_allow_current_process(fc)) {
 416                 buf->f_type = FUSE_SUPER_MAGIC;
 417                 return 0;
 418         }
 419
 420         req = fuse_get_req_nopages(fc);
 421         if (IS_ERR(req))
 422                 return PTR_ERR(req);
 423
 424         memset(&outarg, 0, sizeof(outarg));
 425         req->in.numargs = 0;
 426         req->in.h.opcode = FUSE_STATFS;
 427         req->in.h.nodeid = get_node_id(dentry->d_inode);
 428         req->out.numargs = 1;
 429         req->out.args[0].size =
 430                 fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
 431         req->out.args[0].value = &outarg;
 432         fuse_request_send(fc, req);
 433         err = req->out.h.error;
 434         if (!err)
 435                 convert_fuse_statfs(buf, &outarg.st);
 436         fuse_put_request(fc, req);
 437         return err;
 438 }
 439
 440 enum {
 441         OPT_FD,
 442         OPT_ROOTMODE,
 443         OPT_USER_ID,
 444         OPT_GROUP_ID,
 445         OPT_DEFAULT_PERMISSIONS,
 446         OPT_ALLOW_OTHER,
 447         OPT_MAX_READ,
 448         OPT_BLKSIZE,
 449         OPT_ERR
 450 };
 451
 452 static const match_table_t tokens = {
 453         {OPT_FD,                        "fd=%u"},
 454         {OPT_ROOTMODE,                  "rootmode=%o"},
 455         {OPT_USER_ID,                   "user_id=%u"},
 456         {OPT_GROUP_ID,                  "group_id=%u"},
 457         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
 458         {OPT_ALLOW_OTHER,               "allow_other"},
 459         {OPT_MAX_READ,                  "max_read=%u"},
 460         {OPT_BLKSIZE,                   "blksize=%u"},
 461         {OPT_ERR,                       NULL}
 462 };
 463
 464 static int fuse_match_uint(substring_t *s, unsigned int *res)
 465 {
 466         int err = -ENOMEM;
 467         char *buf = match_strdup(s);
 468         if (buf) {
 469                 err = kstrtouint(buf, 10, res);
 470                 kfree(buf);
 471         }
 472         return err;
 473 }
 474
 475 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
 476 {
 477         char *p;
 478         memset(d, 0, sizeof(struct fuse_mount_data));
 479         d->max_read = ~0;
 480         d->blksize = FUSE_DEFAULT_BLKSIZE;
 481
 482         while ((p = strsep(&opt, ",")) != NULL) {
 483                 int token;
 484                 int value;
 485                 unsigned uv;
 486                 substring_t args[MAX_OPT_ARGS];
 487                 if (!*p)
 488                         continue;
 489
 490                 token = match_token(p, tokens, args);
 491                 switch (token) {
 492                 case OPT_FD:
 493                         if (match_int(&args[0], &value))
 494                                 return 0;
 495                         d->fd = value;
 496                         d->fd_present = 1;
 497                         break;
 498
 499                 case OPT_ROOTMODE:
 500                         if (match_octal(&args[0], &value))
 501                                 return 0;
 502                         if (!fuse_valid_type(value))
 503                                 return 0;
 504                         d->rootmode = value;
 505                         d->rootmode_present = 1;
 506                         break;
 507
 508                 case OPT_USER_ID:
 509                         if (fuse_match_uint(&args[0], &uv))
 510                                 return 0;
 511                         d->user_id = make_kuid(current_user_ns(), uv);
 512                         if (!uid_valid(d->user_id))
 513                                 return 0;
 514                         d->user_id_present = 1;
 515                         break;
 516
 517                 case OPT_GROUP_ID:
 518                         if (fuse_match_uint(&args[0], &uv))
 519                                 return 0;
 520                         d->group_id = make_kgid(current_user_ns(), uv);
 521                         if (!gid_valid(d->group_id))
 522                                 return 0;
 523                         d->group_id_present = 1;
 524                         break;
 525
 526                 case OPT_DEFAULT_PERMISSIONS:
 527                         d->flags |= FUSE_DEFAULT_PERMISSIONS;
 528                         break;
 529
 530                 case OPT_ALLOW_OTHER:
 531                         d->flags |= FUSE_ALLOW_OTHER;
 532                         break;
 533
 534                 case OPT_MAX_READ:
 535                         if (match_int(&args[0], &value))
 536                                 return 0;
 537                         d->max_read = value;
 538                         break;
 539
 540                 case OPT_BLKSIZE:
 541                         if (!is_bdev || match_int(&args[0], &value))
 542                                 return 0;
 543                         d->blksize = value;
 544                         break;
 545
 546                 default:
 547                         return 0;
 548                 }
 549         }
 550
 551         if (!d->fd_present || !d->rootmode_present ||
 552             !d->user_id_present || !d->group_id_present)
 553                 return 0;
 554
 555         return 1;
 556 }
 557
 558 static int fuse_show_options(struct seq_file *m, struct dentry *root)
 559 {
 560         struct super_block *sb = root->d_sb;
 561         struct fuse_conn *fc = get_fuse_conn_super(sb);
 562
 563         seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id));
 564         seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id));
 565         if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
 566                 seq_puts(m, ",default_permissions");
 567         if (fc->flags & FUSE_ALLOW_OTHER)
 568                 seq_puts(m, ",allow_other");
 569         if (fc->max_read != ~0)
 570                 seq_printf(m, ",max_read=%u", fc->max_read);
 571         if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
 572                 seq_printf(m, ",blksize=%lu", sb->s_blocksize);
 573         return 0;
 574 }
 575
 576 void fuse_conn_init(struct fuse_conn *fc)
 577 {
 578         memset(fc, 0, sizeof(*fc));
 579         spin_lock_init(&fc->lock);
 580         mutex_init(&fc->inst_mutex);
 581         init_rwsem(&fc->killsb);
 582         atomic_set(&fc->count, 1);
 583         init_waitqueue_head(&fc->waitq);
 584         init_waitqueue_head(&fc->blocked_waitq);
 585         init_waitqueue_head(&fc->reserved_req_waitq);
 586         INIT_LIST_HEAD(&fc->pending);
 587         INIT_LIST_HEAD(&fc->processing);
 588         INIT_LIST_HEAD(&fc->io);
 589         INIT_LIST_HEAD(&fc->interrupts);
 590         INIT_LIST_HEAD(&fc->bg_queue);
 591         INIT_LIST_HEAD(&fc->entry);
 592         fc->forget_list_tail = &fc->forget_list_head;
 593         atomic_set(&fc->num_waiting, 0);
 594         fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
 595         fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
 596         fc->khctr = 0;
 597         fc->polled_files = RB_ROOT;
 598         fc->reqctr = 0;
 599         fc->blocked = 0;
 600         fc->initialized = 0;
 601         fc->attr_version = 1;
 602         get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 603 }
 604 EXPORT_SYMBOL_GPL(fuse_conn_init);
 605
 606 void fuse_conn_put(struct fuse_conn *fc)
 607 {
 608         if (atomic_dec_and_test(&fc->count)) {
 609                 if (fc->destroy_req)
 610                         fuse_request_free(fc->destroy_req);
 611                 mutex_destroy(&fc->inst_mutex);
 612                 fc->release(fc);
 613         }
 614 }
 615 EXPORT_SYMBOL_GPL(fuse_conn_put);
 616
 617 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
 618 {
 619         atomic_inc(&fc->count);
 620         return fc;
 621 }
 622 EXPORT_SYMBOL_GPL(fuse_conn_get);
 623
 624 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
 625 {
 626         struct fuse_attr attr;
 627         memset(&attr, 0, sizeof(attr));
 628
 629         attr.mode = mode;
 630         attr.ino = FUSE_ROOT_ID;
 631         attr.nlink = 1;
 632         return fuse_iget(sb, 1, 0, &attr, 0, 0);
 633 }
 634
 635 struct fuse_inode_handle {
 636         u64 nodeid;
 637         u32 generation;
 638 };
 639
 640 static struct dentry *fuse_get_dentry(struct super_block *sb,
 641                                       struct fuse_inode_handle *handle)
 642 {
 643         struct fuse_conn *fc = get_fuse_conn_super(sb);
 644         struct inode *inode;
 645         struct dentry *entry;
 646         int err = -ESTALE;
 647
 648         if (handle->nodeid == 0)
 649                 goto out_err;
 650
 651         inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
 652         if (!inode) {
 653                 struct fuse_entry_out outarg;
 654                 struct qstr name;
 655
 656                 if (!fc->export_support)
 657                         goto out_err;
 658
 659                 name.len = 1;
 660                 name.name = ".";
 661                 err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
 662                                        &inode);
 663                 if (err && err != -ENOENT)
 664                         goto out_err;
 665                 if (err || !inode) {
 666                         err = -ESTALE;
 667                         goto out_err;
 668                 }
 669                 err = -EIO;
 670                 if (get_node_id(inode) != handle->nodeid)
 671                         goto out_iput;
 672         }
 673         err = -ESTALE;
 674         if (inode->i_generation != handle->generation)
 675                 goto out_iput;
 676
 677         entry = d_obtain_alias(inode);
 678         if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
 679                 fuse_invalidate_entry_cache(entry);
 680
 681         return entry;
 682
 683  out_iput:
 684         iput(inode);
 685  out_err:
 686         return ERR_PTR(err);
 687 }
 688
 689 static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
 690                            struct inode *parent)
 691 {
 692         int len = parent ? 6 : 3;
 693         u64 nodeid;
 694         u32 generation;
 695
 696         if (*max_len < len) {
 697                 *max_len = len;
 698                 return  FILEID_INVALID;
 699         }
 700
 701         nodeid = get_fuse_inode(inode)->nodeid;
 702         generation = inode->i_generation;
 703
 704         fh[0] = (u32)(nodeid >> 32);
 705         fh[1] = (u32)(nodeid & 0xffffffff);
 706         fh[2] = generation;
 707
 708         if (parent) {
 709                 nodeid = get_fuse_inode(parent)->nodeid;
 710                 generation = parent->i_generation;
 711
 712                 fh[3] = (u32)(nodeid >> 32);
 713                 fh[4] = (u32)(nodeid & 0xffffffff);
 714                 fh[5] = generation;
 715         }
 716
 717         *max_len = len;
 718         return parent ? 0x82 : 0x81;
 719 }
 720
 721 static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
 722                 struct fid *fid, int fh_len, int fh_type)
 723 {
 724         struct fuse_inode_handle handle;
 725
 726         if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
 727                 return NULL;
 728
 729         handle.nodeid = (u64) fid->raw[0] << 32;
 730         handle.nodeid |= (u64) fid->raw[1];
 731         handle.generation = fid->raw[2];
 732         return fuse_get_dentry(sb, &handle);
 733 }
 734
 735 static struct dentry *fuse_fh_to_parent(struct super_block *sb,
 736                 struct fid *fid, int fh_len, int fh_type)
 737 {
 738         struct fuse_inode_handle parent;
 739
 740         if (fh_type != 0x82 || fh_len < 6)
 741                 return NULL;
 742
 743         parent.nodeid = (u64) fid->raw[3] << 32;
 744         parent.nodeid |= (u64) fid->raw[4];
 745         parent.generation = fid->raw[5];
 746         return fuse_get_dentry(sb, &parent);
 747 }
 748
 749 static struct dentry *fuse_get_parent(struct dentry *child)
 750 {
 751         struct inode *child_inode = child->d_inode;
 752         struct fuse_conn *fc = get_fuse_conn(child_inode);
 753         struct inode *inode;
 754         struct dentry *parent;
 755         struct fuse_entry_out outarg;
 756         struct qstr name;
 757         int err;
 758
 759         if (!fc->export_support)
 760                 return ERR_PTR(-ESTALE);
 761
 762         name.len = 2;
 763         name.name = "..";
 764         err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
 765                                &name, &outarg, &inode);
 766         if (err) {
 767                 if (err == -ENOENT)
 768                         return ERR_PTR(-ESTALE);
 769                 return ERR_PTR(err);
 770         }
 771
 772         parent = d_obtain_alias(inode);
 773         if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
 774                 fuse_invalidate_entry_cache(parent);
 775
 776         return parent;
 777 }
 778
 779 static const struct export_operations fuse_export_operations = {
 780         .fh_to_dentry   = fuse_fh_to_dentry,
 781         .fh_to_parent   = fuse_fh_to_parent,
 782         .encode_fh      = fuse_encode_fh,
 783         .get_parent     = fuse_get_parent,
 784 };
 785
 786 static const struct super_operations fuse_super_operations = {
 787         .alloc_inode    = fuse_alloc_inode,
 788         .destroy_inode  = fuse_destroy_inode,
 789         .evict_inode    = fuse_evict_inode,
 790         .drop_inode     = generic_delete_inode,
 791         .remount_fs     = fuse_remount_fs,
 792         .put_super      = fuse_put_super,
 793         .umount_begin   = fuse_umount_begin,
 794         .statfs         = fuse_statfs,
 795         .show_options   = fuse_show_options,
 796 };
 797
 798 static void sanitize_global_limit(unsigned *limit)
 799 {
 800         if (*limit == 0)
 801                 *limit = ((num_physpages << PAGE_SHIFT) >> 13) /
 802                          sizeof(struct fuse_req);
 803
 804         if (*limit >= 1 << 16)
 805                 *limit = (1 << 16) - 1;
 806 }
 807
 808 static int set_global_limit(const char *val, struct kernel_param *kp)
 809 {
 810         int rv;
 811
 812         rv = param_set_uint(val, kp);
 813         if (rv)
 814                 return rv;
 815
 816         sanitize_global_limit((unsigned *)kp->arg);
 817
 818         return 0;
 819 }
 820
 821 static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 822 {
 823         int cap_sys_admin = capable(CAP_SYS_ADMIN);
 824
 825         if (arg->minor < 13)
 826                 return;
 827
 828         sanitize_global_limit(&max_user_bgreq);
 829         sanitize_global_limit(&max_user_congthresh);
 830
 831         if (arg->max_background) {
 832                 fc->max_background = arg->max_background;
 833
 834                 if (!cap_sys_admin && fc->max_background > max_user_bgreq)
 835                         fc->max_background = max_user_bgreq;
 836         }
 837         if (arg->congestion_threshold) {
 838                 fc->congestion_threshold = arg->congestion_threshold;
 839
 840                 if (!cap_sys_admin &&
 841                     fc->congestion_threshold > max_user_congthresh)
 842                         fc->congestion_threshold = max_user_congthresh;
 843         }
 844 }
 845
 846 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 847 {
 848         struct fuse_init_out *arg = &req->misc.init_out;
 849
 850         if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
 851                 fc->conn_error = 1;
 852         else {
 853                 unsigned long ra_pages;
 854
 855                 process_init_limits(fc, arg);
 856
 857                 if (arg->minor >= 6) {
 858                         ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
 859                         if (arg->flags & FUSE_ASYNC_READ)
 860                                 fc->async_read = 1;
 861                         if (!(arg->flags & FUSE_POSIX_LOCKS))
 862                                 fc->no_lock = 1;
 863                         if (arg->minor >= 17) {
 864                                 if (!(arg->flags & FUSE_FLOCK_LOCKS))
 865                                         fc->no_flock = 1;
 866                         } else {
 867                                 if (!(arg->flags & FUSE_POSIX_LOCKS))
 868                                         fc->no_flock = 1;
 869                         }
 870                         if (arg->flags & FUSE_ATOMIC_O_TRUNC)
 871                                 fc->atomic_o_trunc = 1;
 872                         if (arg->minor >= 9) {
 873                                 /* LOOKUP has dependency on proto version */
 874                                 if (arg->flags & FUSE_EXPORT_SUPPORT)
 875                                         fc->export_support = 1;
 876                         }
 877                         if (arg->flags & FUSE_BIG_WRITES)
 878                                 fc->big_writes = 1;
 879                         if (arg->flags & FUSE_DONT_MASK)
 880                                 fc->dont_mask = 1;
 881                         if (arg->flags & FUSE_AUTO_INVAL_DATA)
 882                                 fc->auto_inval_data = 1;
 883                         if (arg->flags & FUSE_DO_READDIRPLUS) {
 884                                 fc->do_readdirplus = 1;
 885                                 if (arg->flags & FUSE_READDIRPLUS_AUTO)
 886                                         fc->readdirplus_auto = 1;
 887                         }
 888                         if (arg->flags & FUSE_ASYNC_DIO)
 889                                 fc->async_dio = 1;
 890                 } else {
 891                         ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 892                         fc->no_lock = 1;
 893                         fc->no_flock = 1;
 894                 }
 895
 896                 fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
 897                 fc->minor = arg->minor;
 898                 fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
 899                 fc->max_write = max_t(unsigned, 4096, fc->max_write);
 900                 fc->conn_init = 1;
 901         }
 902         fc->initialized = 1;
 903         wake_up_all(&fc->blocked_waitq);
 904 }
 905
 906 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
 907 {
 908         struct fuse_init_in *arg = &req->misc.init_in;
 909
 910         arg->major = FUSE_KERNEL_VERSION;
 911         arg->minor = FUSE_KERNEL_MINOR_VERSION;
 912         arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
 913         arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
 914                 FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
 915                 FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
 916                 FUSE_FLOCK_LOCKS | FUSE_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
 917                 FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO;
 918         req->in.h.opcode = FUSE_INIT;
 919         req->in.numargs = 1;
 920         req->in.args[0].size = sizeof(*arg);
 921         req->in.args[0].value = arg;
 922         req->out.numargs = 1;
 923         /* Variable length argument used for backward compatibility
 924            with interface version < 7.5.  Rest of init_out is zeroed
 925            by do_get_request(), so a short reply is not a problem */
 926         req->out.argvar = 1;
 927         req->out.args[0].size = sizeof(struct fuse_init_out);
 928         req->out.args[0].value = &req->misc.init_out;
 929         req->end = process_init_reply;
 930         fuse_request_send_background(fc, req);
 931 }
 932
 933 static void fuse_free_conn(struct fuse_conn *fc)
 934 {
 935         kfree(fc);
 936 }
 937
 938 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
 939 {
 940         int err;
 941
 942         fc->bdi.name = "fuse";
 943         fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 944         /* fuse does it's own writeback accounting */
 945         fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB;
 946
 947         err = bdi_init(&fc->bdi);
 948         if (err)
 949                 return err;
 950
 951         fc->bdi_initialized = 1;
 952
 953         if (sb->s_bdev) {
 954                 err =  bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",
 955                                     MAJOR(fc->dev), MINOR(fc->dev));
 956         } else {
 957                 err = bdi_register_dev(&fc->bdi, fc->dev);
 958         }
 959
 960         if (err)
 961                 return err;
 962
 963         /*
 964          * For a single fuse filesystem use max 1% of dirty +
 965          * writeback threshold.
 966          *
 967          * This gives about 1M of write buffer for memory maps on a
 968          * machine with 1G and 10% dirty_ratio, which should be more
 969          * than enough.
 970          *
 971          * Privileged users can raise it by writing to
 972          *
 973          *    /sys/class/bdi/<bdi>/max_ratio
 974          */
 975         bdi_set_max_ratio(&fc->bdi, 1);
 976
 977         return 0;
 978 }
 979
 980 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 981 {
 982         struct fuse_conn *fc;
 983         struct inode *root;
 984         struct fuse_mount_data d;
 985         struct file *file;
 986         struct dentry *root_dentry;
 987         struct fuse_req *init_req;
 988         int err;
 989         int is_bdev = sb->s_bdev != NULL;
 990
 991         err = -EINVAL;
 992         if (sb->s_flags & MS_MANDLOCK)
 993                 goto err;
 994
 995         sb->s_flags &= ~MS_NOSEC;
 996
 997         if (!parse_fuse_opt((char *) data, &d, is_bdev))
 998                 goto err;
 999
1000         if (is_bdev) {
1001 #ifdef CONFIG_BLOCK
1002                 err = -EINVAL;
1003                 if (!sb_set_blocksize(sb, d.blksize))
1004                         goto err;
1005 #endif
1006         } else {
1007                 sb->s_blocksize = PAGE_CACHE_SIZE;
1008                 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
1009         }
1010         sb->s_magic = FUSE_SUPER_MAGIC;
1011         sb->s_op = &fuse_super_operations;
1012         sb->s_maxbytes = MAX_LFS_FILESIZE;
1013         sb->s_time_gran = 1;
1014         sb->s_export_op = &fuse_export_operations;
1015
1016         file = fget(d.fd);
1017         err = -EINVAL;
1018         if (!file)
1019                 goto err;
1020
1021         if ((file->f_op != &fuse_dev_operations) ||
1022             (file->f_cred->user_ns != &init_user_ns))
1023                 goto err_fput;
1024
1025         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1026         err = -ENOMEM;
1027         if (!fc)
1028                 goto err_fput;
1029
1030         fuse_conn_init(fc);
1031
1032         fc->dev = sb->s_dev;
1033         fc->sb = sb;
1034         err = fuse_bdi_init(fc, sb);
1035         if (err)
1036                 goto err_put_conn;
1037
1038         sb->s_bdi = &fc->bdi;
1039
1040         /* Handle umasking inside the fuse code */
1041         if (sb->s_flags & MS_POSIXACL)
1042                 fc->dont_mask = 1;
1043         sb->s_flags |= MS_POSIXACL;
1044
1045         fc->release = fuse_free_conn;
1046         fc->flags = d.flags;
1047         fc->user_id = d.user_id;
1048         fc->group_id = d.group_id;
1049         fc->max_read = max_t(unsigned, 4096, d.max_read);
1050
1051         /* Used by get_root_inode() */
1052         sb->s_fs_info = fc;
1053
1054         err = -ENOMEM;
1055         root = fuse_get_root_inode(sb, d.rootmode);
1056         root_dentry = d_make_root(root);
1057         if (!root_dentry)
1058                 goto err_put_conn;
1059         /* only now - we want root dentry with NULL ->d_op */
1060         sb->s_d_op = &fuse_dentry_operations;
1061
1062         init_req = fuse_request_alloc(0);
1063         if (!init_req)
1064                 goto err_put_root;
1065         init_req->background = 1;
1066
1067         if (is_bdev) {
1068                 fc->destroy_req = fuse_request_alloc(0);
1069                 if (!fc->destroy_req)
1070                         goto err_free_init_req;
1071         }
1072
1073         mutex_lock(&fuse_mutex);
1074         err = -EINVAL;
1075         if (file->private_data)
1076                 goto err_unlock;
1077
1078         err = fuse_ctl_add_conn(fc);
1079         if (err)
1080                 goto err_unlock;
1081
1082         list_add_tail(&fc->entry, &fuse_conn_list);
1083         sb->s_root = root_dentry;
1084         fc->connected = 1;
1085         file->private_data = fuse_conn_get(fc);
1086         mutex_unlock(&fuse_mutex);
1087         /*
1088          * atomic_dec_and_test() in fput() provides the necessary
1089          * memory barrier for file->private_data to be visible on all
1090          * CPUs after this
1091          */
1092         fput(file);
1093
1094         fuse_send_init(fc, init_req);
1095
1096         return 0;
1097
1098  err_unlock:
1099         mutex_unlock(&fuse_mutex);
1100  err_free_init_req:
1101         fuse_request_free(init_req);
1102  err_put_root:
1103         dput(root_dentry);
1104  err_put_conn:
1105         fuse_bdi_destroy(fc);
1106         fuse_conn_put(fc);
1107  err_fput:
1108         fput(file);
1109  err:
1110         return err;
1111 }
1112
1113 static struct dentry *fuse_mount(struct file_system_type *fs_type,
1114                        int flags, const char *dev_name,
1115                        void *raw_data)
1116 {
1117         return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
1118 }
1119
1120 static void fuse_kill_sb_anon(struct super_block *sb)
1121 {
1122         struct fuse_conn *fc = get_fuse_conn_super(sb);
1123
1124         if (fc) {
1125                 down_write(&fc->killsb);
1126                 fc->sb = NULL;
1127                 up_write(&fc->killsb);
1128         }
1129
1130         kill_anon_super(sb);
1131 }
1132
1133 static struct file_system_type fuse_fs_type = {
1134         .owner          = THIS_MODULE,
1135         .name           = "fuse",
1136         .fs_flags       = FS_HAS_SUBTYPE,
1137         .mount          = fuse_mount,
1138         .kill_sb        = fuse_kill_sb_anon,
1139 };
1140 MODULE_ALIAS_FS("fuse");
1141
1142 #ifdef CONFIG_BLOCK
1143 static struct dentry *fuse_mount_blk(struct file_system_type *fs_type,
1144                            int flags, const char *dev_name,
1145                            void *raw_data)
1146 {
1147         return mount_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super);
1148 }
1149
1150 static void fuse_kill_sb_blk(struct super_block *sb)
1151 {
1152         struct fuse_conn *fc = get_fuse_conn_super(sb);
1153
1154         if (fc) {
1155                 down_write(&fc->killsb);
1156                 fc->sb = NULL;
1157                 up_write(&fc->killsb);
1158         }
1159
1160         kill_block_super(sb);
1161 }
1162
1163 static struct file_system_type fuseblk_fs_type = {
1164         .owner          = THIS_MODULE,
1165         .name           = "fuseblk",
1166         .mount          = fuse_mount_blk,
1167         .kill_sb        = fuse_kill_sb_blk,
1168         .fs_flags       = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1169 };
1170 MODULE_ALIAS_FS("fuseblk");
1171
1172 static inline int register_fuseblk(void)
1173 {
1174         return register_filesystem(&fuseblk_fs_type);
1175 }
1176
1177 static inline void unregister_fuseblk(void)
1178 {
1179         unregister_filesystem(&fuseblk_fs_type);
1180 }
1181 #else
1182 static inline int register_fuseblk(void)
1183 {
1184         return 0;
1185 }
1186
1187 static inline void unregister_fuseblk(void)
1188 {
1189 }
1190 #endif
1191
1192 static void fuse_inode_init_once(void *foo)
1193 {
1194         struct inode *inode = foo;
1195
1196         inode_init_once(inode);
1197 }
1198
1199 static int __init fuse_fs_init(void)
1200 {
1201         int err;
1202
1203         fuse_inode_cachep = kmem_cache_create("fuse_inode",
1204                                               sizeof(struct fuse_inode),
1205                                               0, SLAB_HWCACHE_ALIGN,
1206                                               fuse_inode_init_once);
1207         err = -ENOMEM;
1208         if (!fuse_inode_cachep)
1209                 goto out;
1210
1211         err = register_fuseblk();
1212         if (err)
1213                 goto out2;
1214
1215         err = register_filesystem(&fuse_fs_type);
1216         if (err)
1217                 goto out3;
1218
1219         return 0;
1220
1221  out3:
1222         unregister_fuseblk();
1223  out2:
1224         kmem_cache_destroy(fuse_inode_cachep);
1225  out:
1226         return err;
1227 }
1228
1229 static void fuse_fs_cleanup(void)
1230 {
1231         unregister_filesystem(&fuse_fs_type);
1232         unregister_fuseblk();
1233
1234         /*
1235          * Make sure all delayed rcu free inodes are flushed before we
1236          * destroy cache.
1237          */
1238         rcu_barrier();
1239         kmem_cache_destroy(fuse_inode_cachep);
1240 }
1241
1242 static struct kobject *fuse_kobj;
1243 static struct kobject *connections_kobj;
1244
1245 static int fuse_sysfs_init(void)
1246 {
1247         int err;
1248
1249         fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1250         if (!fuse_kobj) {
1251                 err = -ENOMEM;
1252                 goto out_err;
1253         }
1254
1255         connections_kobj = kobject_create_and_add("connections", fuse_kobj);
1256         if (!connections_kobj) {
1257                 err = -ENOMEM;
1258                 goto out_fuse_unregister;
1259         }
1260
1261         return 0;
1262
1263  out_fuse_unregister:
1264         kobject_put(fuse_kobj);
1265  out_err:
1266         return err;
1267 }
1268
1269 static void fuse_sysfs_cleanup(void)
1270 {
1271         kobject_put(connections_kobj);
1272         kobject_put(fuse_kobj);
1273 }
1274
1275 static int __init fuse_init(void)
1276 {
1277         int res;
1278
1279         printk(KERN_INFO "fuse init (API version %i.%i)\n",
1280                FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1281
1282         INIT_LIST_HEAD(&fuse_conn_list);
1283         res = fuse_fs_init();
1284         if (res)
1285                 goto err;
1286
1287         res = fuse_dev_init();
1288         if (res)
1289                 goto err_fs_cleanup;
1290
1291         res = fuse_sysfs_init();
1292         if (res)
1293                 goto err_dev_cleanup;
1294
1295         res = fuse_ctl_init();
1296         if (res)
1297                 goto err_sysfs_cleanup;
1298
1299         sanitize_global_limit(&max_user_bgreq);
1300         sanitize_global_limit(&max_user_congthresh);
1301
1302         return 0;
1303
1304  err_sysfs_cleanup:
1305         fuse_sysfs_cleanup();
1306  err_dev_cleanup:
1307         fuse_dev_cleanup();
1308  err_fs_cleanup:
1309         fuse_fs_cleanup();
1310  err:
1311         return res;
1312 }
1313
1314 static void __exit fuse_exit(void)
1315 {
1316         printk(KERN_DEBUG "fuse exit\n");
1317
1318         fuse_ctl_cleanup();
1319         fuse_sysfs_cleanup();
1320         fuse_fs_cleanup();
1321         fuse_dev_cleanup();
1322 }
1323
1324 module_init(fuse_init);
1325 module_exit(fuse_exit);