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