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