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