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   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 static struct inode *fuse_alloc_inode(struct super_block *sb)
  75 {
  76         struct inode *inode;
  77         struct fuse_inode *fi;
  78
  79         inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
  80         if (!inode)
  81                 return NULL;
  82
  83         fi = get_fuse_inode(inode);
  84         fi->i_time = 0;
  85         fi->nodeid = 0;
  86         fi->nlookup = 0;
  87         fi->attr_version = 0;
  88         fi->writectr = 0;
  89         INIT_LIST_HEAD(&fi->write_files);
  90         INIT_LIST_HEAD(&fi->queued_writes);
  91         INIT_LIST_HEAD(&fi->writepages);
  92         init_waitqueue_head(&fi->page_waitq);
  93         fi->forget_req = fuse_request_alloc();
  94         if (!fi->forget_req) {
  95                 kmem_cache_free(fuse_inode_cachep, inode);
  96                 return NULL;
  97         }
  98
  99         return inode;
 100 }
 101
 102 static void fuse_destroy_inode(struct inode *inode)
 103 {
 104         struct fuse_inode *fi = get_fuse_inode(inode);
 105         BUG_ON(!list_empty(&fi->write_files));
 106         BUG_ON(!list_empty(&fi->queued_writes));
 107         if (fi->forget_req)
 108                 fuse_request_free(fi->forget_req);
 109         kmem_cache_free(fuse_inode_cachep, inode);
 110 }
 111
 112 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 113                       u64 nodeid, u64 nlookup)
 114 {
 115         struct fuse_forget_in *inarg = &req->misc.forget_in;
 116         inarg->nlookup = nlookup;
 117         req->in.h.opcode = FUSE_FORGET;
 118         req->in.h.nodeid = nodeid;
 119         req->in.numargs = 1;
 120         req->in.args[0].size = sizeof(struct fuse_forget_in);
 121         req->in.args[0].value = inarg;
 122         fuse_request_send_noreply(fc, req);
 123 }
 124
 125 static void fuse_clear_inode(struct inode *inode)
 126 {
 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_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
 131                 fi->forget_req = 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 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 144                                    u64 attr_valid)
 145 {
 146         struct fuse_conn *fc = get_fuse_conn(inode);
 147         struct fuse_inode *fi = get_fuse_inode(inode);
 148
 149         fi->attr_version = ++fc->attr_version;
 150         fi->i_time = attr_valid;
 151
 152         inode->i_ino     = attr->ino;
 153         inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
 154         inode->i_nlink   = attr->nlink;
 155         inode->i_uid     = attr->uid;
 156         inode->i_gid     = attr->gid;
 157         inode->i_blocks  = attr->blocks;
 158         inode->i_atime.tv_sec   = attr->atime;
 159         inode->i_atime.tv_nsec  = attr->atimensec;
 160         inode->i_mtime.tv_sec   = attr->mtime;
 161         inode->i_mtime.tv_nsec  = attr->mtimensec;
 162         inode->i_ctime.tv_sec   = attr->ctime;
 163         inode->i_ctime.tv_nsec  = attr->ctimensec;
 164
 165         if (attr->blksize != 0)
 166                 inode->i_blkbits = ilog2(attr->blksize);
 167         else
 168                 inode->i_blkbits = inode->i_sb->s_blocksize_bits;
 169
 170         /*
 171          * Don't set the sticky bit in i_mode, unless we want the VFS
 172          * to check permissions.  This prevents failures due to the
 173          * check in may_delete().
 174          */
 175         fi->orig_i_mode = inode->i_mode;
 176         if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
 177                 inode->i_mode &= ~S_ISVTX;
 178 }
 179
 180 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 181                             u64 attr_valid, u64 attr_version)
 182 {
 183         struct fuse_conn *fc = get_fuse_conn(inode);
 184         struct fuse_inode *fi = get_fuse_inode(inode);
 185         loff_t oldsize;
 186
 187         spin_lock(&fc->lock);
 188         if (attr_version != 0 && fi->attr_version > attr_version) {
 189                 spin_unlock(&fc->lock);
 190                 return;
 191         }
 192
 193         fuse_change_attributes_common(inode, attr, attr_valid);
 194
 195         oldsize = inode->i_size;
 196         i_size_write(inode, attr->size);
 197         spin_unlock(&fc->lock);
 198
 199         if (S_ISREG(inode->i_mode) && oldsize != attr->size) {
 200                 truncate_pagecache(inode, oldsize, attr->size);
 201                 invalidate_inode_pages2(inode->i_mapping);
 202         }
 203 }
 204
 205 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 206 {
 207         inode->i_mode = attr->mode & S_IFMT;
 208         inode->i_size = attr->size;
 209         if (S_ISREG(inode->i_mode)) {
 210                 fuse_init_common(inode);
 211                 fuse_init_file_inode(inode);
 212         } else if (S_ISDIR(inode->i_mode))
 213                 fuse_init_dir(inode);
 214         else if (S_ISLNK(inode->i_mode))
 215                 fuse_init_symlink(inode);
 216         else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 217                  S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 218                 fuse_init_common(inode);
 219                 init_special_inode(inode, inode->i_mode,
 220                                    new_decode_dev(attr->rdev));
 221         } else
 222                 BUG();
 223 }
 224
 225 int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 226 {
 227         u64 nodeid = *(u64 *) _nodeidp;
 228         if (get_node_id(inode) == nodeid)
 229                 return 1;
 230         else
 231                 return 0;
 232 }
 233
 234 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 235 {
 236         u64 nodeid = *(u64 *) _nodeidp;
 237         get_fuse_inode(inode)->nodeid = nodeid;
 238         return 0;
 239 }
 240
 241 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 242                         int generation, struct fuse_attr *attr,
 243                         u64 attr_valid, u64 attr_version)
 244 {
 245         struct inode *inode;
 246         struct fuse_inode *fi;
 247         struct fuse_conn *fc = get_fuse_conn_super(sb);
 248
 249  retry:
 250         inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 251         if (!inode)
 252                 return NULL;
 253
 254         if ((inode->i_state & I_NEW)) {
 255                 inode->i_flags |= S_NOATIME|S_NOCMTIME;
 256                 inode->i_generation = generation;
 257                 inode->i_data.backing_dev_info = &fc->bdi;
 258                 fuse_init_inode(inode, attr);
 259                 unlock_new_inode(inode);
 260         } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 261                 /* Inode has changed type, any I/O on the old should fail */
 262                 make_bad_inode(inode);
 263                 iput(inode);
 264                 goto retry;
 265         }
 266
 267         fi = get_fuse_inode(inode);
 268         spin_lock(&fc->lock);
 269         fi->nlookup++;
 270         spin_unlock(&fc->lock);
 271         fuse_change_attributes(inode, attr, attr_valid, attr_version);
 272
 273         return inode;
 274 }
 275
 276 int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
 277                              loff_t offset, loff_t len)
 278 {
 279         struct inode *inode;
 280         pgoff_t pg_start;
 281         pgoff_t pg_end;
 282
 283         inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
 284         if (!inode)
 285                 return -ENOENT;
 286
 287         fuse_invalidate_attr(inode);
 288         if (offset >= 0) {
 289                 pg_start = offset >> PAGE_CACHE_SHIFT;
 290                 if (len <= 0)
 291                         pg_end = -1;
 292                 else
 293                         pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
 294                 invalidate_inode_pages2_range(inode->i_mapping,
 295                                               pg_start, pg_end);
 296         }
 297         iput(inode);
 298         return 0;
 299 }
 300
 301 static void fuse_umount_begin(struct super_block *sb)
 302 {
 303         fuse_abort_conn(get_fuse_conn_super(sb));
 304 }
 305
 306 static void fuse_send_destroy(struct fuse_conn *fc)
 307 {
 308         struct fuse_req *req = fc->destroy_req;
 309         if (req && fc->conn_init) {
 310                 fc->destroy_req = NULL;
 311                 req->in.h.opcode = FUSE_DESTROY;
 312                 req->force = 1;
 313                 fuse_request_send(fc, req);
 314                 fuse_put_request(fc, req);
 315         }
 316 }
 317
 318 static void fuse_bdi_destroy(struct fuse_conn *fc)
 319 {
 320         if (fc->bdi_initialized)
 321                 bdi_destroy(&fc->bdi);
 322 }
 323
 324 void fuse_conn_kill(struct fuse_conn *fc)
 325 {
 326         spin_lock(&fc->lock);
 327         fc->connected = 0;
 328         fc->blocked = 0;
 329         spin_unlock(&fc->lock);
 330         /* Flush all readers on this fs */
 331         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 332         wake_up_all(&fc->waitq);
 333         wake_up_all(&fc->blocked_waitq);
 334         wake_up_all(&fc->reserved_req_waitq);
 335         mutex_lock(&fuse_mutex);
 336         list_del(&fc->entry);
 337         fuse_ctl_remove_conn(fc);
 338         mutex_unlock(&fuse_mutex);
 339         fuse_bdi_destroy(fc);
 340 }
 341 EXPORT_SYMBOL_GPL(fuse_conn_kill);
 342
 343 static void fuse_put_super(struct super_block *sb)
 344 {
 345         struct fuse_conn *fc = get_fuse_conn_super(sb);
 346
 347         fuse_send_destroy(fc);
 348         fuse_conn_kill(fc);
 349         fuse_conn_put(fc);
 350 }
 351
 352 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
 353 {
 354         stbuf->f_type    = FUSE_SUPER_MAGIC;
 355         stbuf->f_bsize   = attr->bsize;
 356         stbuf->f_frsize  = attr->frsize;
 357         stbuf->f_blocks  = attr->blocks;
 358         stbuf->f_bfree   = attr->bfree;
 359         stbuf->f_bavail  = attr->bavail;
 360         stbuf->f_files   = attr->files;
 361         stbuf->f_ffree   = attr->ffree;
 362         stbuf->f_namelen = attr->namelen;
 363         /* fsid is left zero */
 364 }
 365
 366 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 367 {
 368         struct super_block *sb = dentry->d_sb;
 369         struct fuse_conn *fc = get_fuse_conn_super(sb);
 370         struct fuse_req *req;
 371         struct fuse_statfs_out outarg;
 372         int err;
 373
 374         if (!fuse_allow_task(fc, current)) {
 375                 buf->f_type = FUSE_SUPER_MAGIC;
 376                 return 0;
 377         }
 378
 379         req = fuse_get_req(fc);
 380         if (IS_ERR(req))
 381                 return PTR_ERR(req);
 382
 383         memset(&outarg, 0, sizeof(outarg));
 384         req->in.numargs = 0;
 385         req->in.h.opcode = FUSE_STATFS;
 386         req->in.h.nodeid = get_node_id(dentry->d_inode);
 387         req->out.numargs = 1;
 388         req->out.args[0].size =
 389                 fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
 390         req->out.args[0].value = &outarg;
 391         fuse_request_send(fc, req);
 392         err = req->out.h.error;
 393         if (!err)
 394                 convert_fuse_statfs(buf, &outarg.st);
 395         fuse_put_request(fc, req);
 396         return err;
 397 }
 398
 399 enum {
 400         OPT_FD,
 401         OPT_ROOTMODE,
 402         OPT_USER_ID,
 403         OPT_GROUP_ID,
 404         OPT_DEFAULT_PERMISSIONS,
 405         OPT_ALLOW_OTHER,
 406         OPT_MAX_READ,
 407         OPT_BLKSIZE,
 408         OPT_ERR
 409 };
 410
 411 static const match_table_t tokens = {
 412         {OPT_FD,                        "fd=%u"},
 413         {OPT_ROOTMODE,                  "rootmode=%o"},
 414         {OPT_USER_ID,                   "user_id=%u"},
 415         {OPT_GROUP_ID,                  "group_id=%u"},
 416         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
 417         {OPT_ALLOW_OTHER,               "allow_other"},
 418         {OPT_MAX_READ,                  "max_read=%u"},
 419         {OPT_BLKSIZE,                   "blksize=%u"},
 420         {OPT_ERR,                       NULL}
 421 };
 422
 423 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
 424 {
 425         char *p;
 426         memset(d, 0, sizeof(struct fuse_mount_data));
 427         d->max_read = ~0;
 428         d->blksize = FUSE_DEFAULT_BLKSIZE;
 429
 430         while ((p = strsep(&opt, ",")) != NULL) {
 431                 int token;
 432                 int value;
 433                 substring_t args[MAX_OPT_ARGS];
 434                 if (!*p)
 435                         continue;
 436
 437                 token = match_token(p, tokens, args);
 438                 switch (token) {
 439                 case OPT_FD:
 440                         if (match_int(&args[0], &value))
 441                                 return 0;
 442                         d->fd = value;
 443                         d->fd_present = 1;
 444                         break;
 445
 446                 case OPT_ROOTMODE:
 447                         if (match_octal(&args[0], &value))
 448                                 return 0;
 449                         if (!fuse_valid_type(value))
 450                                 return 0;
 451                         d->rootmode = value;
 452                         d->rootmode_present = 1;
 453                         break;
 454
 455                 case OPT_USER_ID:
 456                         if (match_int(&args[0], &value))
 457                                 return 0;
 458                         d->user_id = value;
 459                         d->user_id_present = 1;
 460                         break;
 461
 462                 case OPT_GROUP_ID:
 463                         if (match_int(&args[0], &value))
 464                                 return 0;
 465                         d->group_id = value;
 466                         d->group_id_present = 1;
 467                         break;
 468
 469                 case OPT_DEFAULT_PERMISSIONS:
 470                         d->flags |= FUSE_DEFAULT_PERMISSIONS;
 471                         break;
 472
 473                 case OPT_ALLOW_OTHER:
 474                         d->flags |= FUSE_ALLOW_OTHER;
 475                         break;
 476
 477                 case OPT_MAX_READ:
 478                         if (match_int(&args[0], &value))
 479                                 return 0;
 480                         d->max_read = value;
 481                         break;
 482
 483                 case OPT_BLKSIZE:
 484                         if (!is_bdev || match_int(&args[0], &value))
 485                                 return 0;
 486                         d->blksize = value;
 487                         break;
 488
 489                 default:
 490                         return 0;
 491                 }
 492         }
 493
 494         if (!d->fd_present || !d->rootmode_present ||
 495             !d->user_id_present || !d->group_id_present)
 496                 return 0;
 497
 498         return 1;
 499 }
 500
 501 static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
 502 {
 503         struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_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 (mnt->mnt_sb->s_bdev &&
 514             mnt->mnt_sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
 515                 seq_printf(m, ",blksize=%lu", mnt->mnt_sb->s_blocksize);
 516         return 0;
 517 }
 518
 519 void fuse_conn_init(struct fuse_conn *fc)
 520 {
 521         memset(fc, 0, sizeof(*fc));
 522         spin_lock_init(&fc->lock);
 523         mutex_init(&fc->inst_mutex);
 524         init_rwsem(&fc->killsb);
 525         atomic_set(&fc->count, 1);
 526         init_waitqueue_head(&fc->waitq);
 527         init_waitqueue_head(&fc->blocked_waitq);
 528         init_waitqueue_head(&fc->reserved_req_waitq);
 529         INIT_LIST_HEAD(&fc->pending);
 530         INIT_LIST_HEAD(&fc->processing);
 531         INIT_LIST_HEAD(&fc->io);
 532         INIT_LIST_HEAD(&fc->interrupts);
 533         INIT_LIST_HEAD(&fc->bg_queue);
 534         INIT_LIST_HEAD(&fc->entry);
 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                 entry->d_op = &fuse_dentry_operations;
 621                 fuse_invalidate_entry_cache(entry);
 622         }
 623
 624         return entry;
 625
 626  out_iput:
 627         iput(inode);
 628  out_err:
 629         return ERR_PTR(err);
 630 }
 631
 632 static int fuse_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
 633                            int connectable)
 634 {
 635         struct inode *inode = dentry->d_inode;
 636         bool encode_parent = connectable && !S_ISDIR(inode->i_mode);
 637         int len = encode_parent ? 6 : 3;
 638         u64 nodeid;
 639         u32 generation;
 640
 641         if (*max_len < len)
 642                 return  255;
 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                 parent->d_op = &fuse_dentry_operations;
 723                 fuse_invalidate_entry_cache(parent);
 724         }
 725
 726         return parent;
 727 }
 728
 729 static const struct export_operations fuse_export_operations = {
 730         .fh_to_dentry   = fuse_fh_to_dentry,
 731         .fh_to_parent   = fuse_fh_to_parent,
 732         .encode_fh      = fuse_encode_fh,
 733         .get_parent     = fuse_get_parent,
 734 };
 735
 736 static const struct super_operations fuse_super_operations = {
 737         .alloc_inode    = fuse_alloc_inode,
 738         .destroy_inode  = fuse_destroy_inode,
 739         .clear_inode    = fuse_clear_inode,
 740         .drop_inode     = generic_delete_inode,
 741         .remount_fs     = fuse_remount_fs,
 742         .put_super      = fuse_put_super,
 743         .umount_begin   = fuse_umount_begin,
 744         .statfs         = fuse_statfs,
 745         .show_options   = fuse_show_options,
 746 };
 747
 748 static void sanitize_global_limit(unsigned *limit)
 749 {
 750         if (*limit == 0)
 751                 *limit = ((num_physpages << PAGE_SHIFT) >> 13) /
 752                          sizeof(struct fuse_req);
 753
 754         if (*limit >= 1 << 16)
 755                 *limit = (1 << 16) - 1;
 756 }
 757
 758 static int set_global_limit(const char *val, struct kernel_param *kp)
 759 {
 760         int rv;
 761
 762         rv = param_set_uint(val, kp);
 763         if (rv)
 764                 return rv;
 765
 766         sanitize_global_limit((unsigned *)kp->arg);
 767
 768         return 0;
 769 }
 770
 771 static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 772 {
 773         int cap_sys_admin = capable(CAP_SYS_ADMIN);
 774
 775         if (arg->minor < 13)
 776                 return;
 777
 778         sanitize_global_limit(&max_user_bgreq);
 779         sanitize_global_limit(&max_user_congthresh);
 780
 781         if (arg->max_background) {
 782                 fc->max_background = arg->max_background;
 783
 784                 if (!cap_sys_admin && fc->max_background > max_user_bgreq)
 785                         fc->max_background = max_user_bgreq;
 786         }
 787         if (arg->congestion_threshold) {
 788                 fc->congestion_threshold = arg->congestion_threshold;
 789
 790                 if (!cap_sys_admin &&
 791                     fc->congestion_threshold > max_user_congthresh)
 792                         fc->congestion_threshold = max_user_congthresh;
 793         }
 794 }
 795
 796 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 797 {
 798         struct fuse_init_out *arg = &req->misc.init_out;
 799
 800         if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
 801                 fc->conn_error = 1;
 802         else {
 803                 unsigned long ra_pages;
 804
 805                 process_init_limits(fc, arg);
 806
 807                 if (arg->minor >= 6) {
 808                         ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
 809                         if (arg->flags & FUSE_ASYNC_READ)
 810                                 fc->async_read = 1;
 811                         if (!(arg->flags & FUSE_POSIX_LOCKS))
 812                                 fc->no_lock = 1;
 813                         if (arg->flags & FUSE_ATOMIC_O_TRUNC)
 814                                 fc->atomic_o_trunc = 1;
 815                         if (arg->minor >= 9) {
 816                                 /* LOOKUP has dependency on proto version */
 817                                 if (arg->flags & FUSE_EXPORT_SUPPORT)
 818                                         fc->export_support = 1;
 819                         }
 820                         if (arg->flags & FUSE_BIG_WRITES)
 821                                 fc->big_writes = 1;
 822                         if (arg->flags & FUSE_DONT_MASK)
 823                                 fc->dont_mask = 1;
 824                 } else {
 825                         ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 826                         fc->no_lock = 1;
 827                 }
 828
 829                 fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
 830                 fc->minor = arg->minor;
 831                 fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
 832                 fc->max_write = max_t(unsigned, 4096, fc->max_write);
 833                 fc->conn_init = 1;
 834         }
 835         fc->blocked = 0;
 836         wake_up_all(&fc->blocked_waitq);
 837 }
 838
 839 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
 840 {
 841         struct fuse_init_in *arg = &req->misc.init_in;
 842
 843         arg->major = FUSE_KERNEL_VERSION;
 844         arg->minor = FUSE_KERNEL_MINOR_VERSION;
 845         arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
 846         arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
 847                 FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK;
 848         req->in.h.opcode = FUSE_INIT;
 849         req->in.numargs = 1;
 850         req->in.args[0].size = sizeof(*arg);
 851         req->in.args[0].value = arg;
 852         req->out.numargs = 1;
 853         /* Variable length arguement used for backward compatibility
 854            with interface version < 7.5.  Rest of init_out is zeroed
 855            by do_get_request(), so a short reply is not a problem */
 856         req->out.argvar = 1;
 857         req->out.args[0].size = sizeof(struct fuse_init_out);
 858         req->out.args[0].value = &req->misc.init_out;
 859         req->end = process_init_reply;
 860         fuse_request_send_background(fc, req);
 861 }
 862
 863 static void fuse_free_conn(struct fuse_conn *fc)
 864 {
 865         kfree(fc);
 866 }
 867
 868 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
 869 {
 870         int err;
 871
 872         fc->bdi.name = "fuse";
 873         fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 874         fc->bdi.unplug_io_fn = default_unplug_io_fn;
 875         /* fuse does it's own writeback accounting */
 876         fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB;
 877
 878         err = bdi_init(&fc->bdi);
 879         if (err)
 880                 return err;
 881
 882         fc->bdi_initialized = 1;
 883
 884         if (sb->s_bdev) {
 885                 err =  bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",
 886                                     MAJOR(fc->dev), MINOR(fc->dev));
 887         } else {
 888                 err = bdi_register_dev(&fc->bdi, fc->dev);
 889         }
 890
 891         if (err)
 892                 return err;
 893
 894         /*
 895          * For a single fuse filesystem use max 1% of dirty +
 896          * writeback threshold.
 897          *
 898          * This gives about 1M of write buffer for memory maps on a
 899          * machine with 1G and 10% dirty_ratio, which should be more
 900          * than enough.
 901          *
 902          * Privileged users can raise it by writing to
 903          *
 904          *    /sys/class/bdi/<bdi>/max_ratio
 905          */
 906         bdi_set_max_ratio(&fc->bdi, 1);
 907
 908         return 0;
 909 }
 910
 911 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 912 {
 913         struct fuse_conn *fc;
 914         struct inode *root;
 915         struct fuse_mount_data d;
 916         struct file *file;
 917         struct dentry *root_dentry;
 918         struct fuse_req *init_req;
 919         int err;
 920         int is_bdev = sb->s_bdev != NULL;
 921
 922         err = -EINVAL;
 923         if (sb->s_flags & MS_MANDLOCK)
 924                 goto err;
 925
 926         if (!parse_fuse_opt((char *) data, &d, is_bdev))
 927                 goto err;
 928
 929         if (is_bdev) {
 930 #ifdef CONFIG_BLOCK
 931                 err = -EINVAL;
 932                 if (!sb_set_blocksize(sb, d.blksize))
 933                         goto err;
 934 #endif
 935         } else {
 936                 sb->s_blocksize = PAGE_CACHE_SIZE;
 937                 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 938         }
 939         sb->s_magic = FUSE_SUPER_MAGIC;
 940         sb->s_op = &fuse_super_operations;
 941         sb->s_maxbytes = MAX_LFS_FILESIZE;
 942         sb->s_export_op = &fuse_export_operations;
 943
 944         file = fget(d.fd);
 945         err = -EINVAL;
 946         if (!file)
 947                 goto err;
 948
 949         if (file->f_op != &fuse_dev_operations)
 950                 goto err_fput;
 951
 952         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
 953         err = -ENOMEM;
 954         if (!fc)
 955                 goto err_fput;
 956
 957         fuse_conn_init(fc);
 958
 959         fc->dev = sb->s_dev;
 960         fc->sb = sb;
 961         err = fuse_bdi_init(fc, sb);
 962         if (err)
 963                 goto err_put_conn;
 964
 965         sb->s_bdi = &fc->bdi;
 966
 967         /* Handle umasking inside the fuse code */
 968         if (sb->s_flags & MS_POSIXACL)
 969                 fc->dont_mask = 1;
 970         sb->s_flags |= MS_POSIXACL;
 971
 972         fc->release = fuse_free_conn;
 973         fc->flags = d.flags;
 974         fc->user_id = d.user_id;
 975         fc->group_id = d.group_id;
 976         fc->max_read = max_t(unsigned, 4096, d.max_read);
 977
 978         /* Used by get_root_inode() */
 979         sb->s_fs_info = fc;
 980
 981         err = -ENOMEM;
 982         root = fuse_get_root_inode(sb, d.rootmode);
 983         if (!root)
 984                 goto err_put_conn;
 985
 986         root_dentry = d_alloc_root(root);
 987         if (!root_dentry) {
 988                 iput(root);
 989                 goto err_put_conn;
 990         }
 991
 992         init_req = fuse_request_alloc();
 993         if (!init_req)
 994                 goto err_put_root;
 995
 996         if (is_bdev) {
 997                 fc->destroy_req = fuse_request_alloc();
 998                 if (!fc->destroy_req)
 999                         goto err_free_init_req;
1000         }
1001
1002         mutex_lock(&fuse_mutex);
1003         err = -EINVAL;
1004         if (file->private_data)
1005                 goto err_unlock;
1006
1007         err = fuse_ctl_add_conn(fc);
1008         if (err)
1009                 goto err_unlock;
1010
1011         list_add_tail(&fc->entry, &fuse_conn_list);
1012         sb->s_root = root_dentry;
1013         fc->connected = 1;
1014         file->private_data = fuse_conn_get(fc);
1015         mutex_unlock(&fuse_mutex);
1016         /*
1017          * atomic_dec_and_test() in fput() provides the necessary
1018          * memory barrier for file->private_data to be visible on all
1019          * CPUs after this
1020          */
1021         fput(file);
1022
1023         fuse_send_init(fc, init_req);
1024
1025         return 0;
1026
1027  err_unlock:
1028         mutex_unlock(&fuse_mutex);
1029  err_free_init_req:
1030         fuse_request_free(init_req);
1031  err_put_root:
1032         dput(root_dentry);
1033  err_put_conn:
1034         fuse_bdi_destroy(fc);
1035         fuse_conn_put(fc);
1036  err_fput:
1037         fput(file);
1038  err:
1039         return err;
1040 }
1041
1042 static int fuse_get_sb(struct file_system_type *fs_type,
1043                        int flags, const char *dev_name,
1044                        void *raw_data, struct vfsmount *mnt)
1045 {
1046         return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super, mnt);
1047 }
1048
1049 static void fuse_kill_sb_anon(struct super_block *sb)
1050 {
1051         struct fuse_conn *fc = get_fuse_conn_super(sb);
1052
1053         if (fc) {
1054                 down_write(&fc->killsb);
1055                 fc->sb = NULL;
1056                 up_write(&fc->killsb);
1057         }
1058
1059         kill_anon_super(sb);
1060 }
1061
1062 static struct file_system_type fuse_fs_type = {
1063         .owner          = THIS_MODULE,
1064         .name           = "fuse",
1065         .fs_flags       = FS_HAS_SUBTYPE,
1066         .get_sb         = fuse_get_sb,
1067         .kill_sb        = fuse_kill_sb_anon,
1068 };
1069
1070 #ifdef CONFIG_BLOCK
1071 static int fuse_get_sb_blk(struct file_system_type *fs_type,
1072                            int flags, const char *dev_name,
1073                            void *raw_data, struct vfsmount *mnt)
1074 {
1075         return get_sb_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super,
1076                            mnt);
1077 }
1078
1079 static void fuse_kill_sb_blk(struct super_block *sb)
1080 {
1081         struct fuse_conn *fc = get_fuse_conn_super(sb);
1082
1083         if (fc) {
1084                 down_write(&fc->killsb);
1085                 fc->sb = NULL;
1086                 up_write(&fc->killsb);
1087         }
1088
1089         kill_block_super(sb);
1090 }
1091
1092 static struct file_system_type fuseblk_fs_type = {
1093         .owner          = THIS_MODULE,
1094         .name           = "fuseblk",
1095         .get_sb         = fuse_get_sb_blk,
1096         .kill_sb        = fuse_kill_sb_blk,
1097         .fs_flags       = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1098 };
1099
1100 static inline int register_fuseblk(void)
1101 {
1102         return register_filesystem(&fuseblk_fs_type);
1103 }
1104
1105 static inline void unregister_fuseblk(void)
1106 {
1107         unregister_filesystem(&fuseblk_fs_type);
1108 }
1109 #else
1110 static inline int register_fuseblk(void)
1111 {
1112         return 0;
1113 }
1114
1115 static inline void unregister_fuseblk(void)
1116 {
1117 }
1118 #endif
1119
1120 static void fuse_inode_init_once(void *foo)
1121 {
1122         struct inode *inode = foo;
1123
1124         inode_init_once(inode);
1125 }
1126
1127 static int __init fuse_fs_init(void)
1128 {
1129         int err;
1130
1131         err = register_filesystem(&fuse_fs_type);
1132         if (err)
1133                 goto out;
1134
1135         err = register_fuseblk();
1136         if (err)
1137                 goto out_unreg;
1138
1139         fuse_inode_cachep = kmem_cache_create("fuse_inode",
1140                                               sizeof(struct fuse_inode),
1141                                               0, SLAB_HWCACHE_ALIGN,
1142                                               fuse_inode_init_once);
1143         err = -ENOMEM;
1144         if (!fuse_inode_cachep)
1145                 goto out_unreg2;
1146
1147         return 0;
1148
1149  out_unreg2:
1150         unregister_fuseblk();
1151  out_unreg:
1152         unregister_filesystem(&fuse_fs_type);
1153  out:
1154         return err;
1155 }
1156
1157 static void fuse_fs_cleanup(void)
1158 {
1159         unregister_filesystem(&fuse_fs_type);
1160         unregister_fuseblk();
1161         kmem_cache_destroy(fuse_inode_cachep);
1162 }
1163
1164 static struct kobject *fuse_kobj;
1165 static struct kobject *connections_kobj;
1166
1167 static int fuse_sysfs_init(void)
1168 {
1169         int err;
1170
1171         fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1172         if (!fuse_kobj) {
1173                 err = -ENOMEM;
1174                 goto out_err;
1175         }
1176
1177         connections_kobj = kobject_create_and_add("connections", fuse_kobj);
1178         if (!connections_kobj) {
1179                 err = -ENOMEM;
1180                 goto out_fuse_unregister;
1181         }
1182
1183         return 0;
1184
1185  out_fuse_unregister:
1186         kobject_put(fuse_kobj);
1187  out_err:
1188         return err;
1189 }
1190
1191 static void fuse_sysfs_cleanup(void)
1192 {
1193         kobject_put(connections_kobj);
1194         kobject_put(fuse_kobj);
1195 }
1196
1197 static int __init fuse_init(void)
1198 {
1199         int res;
1200
1201         printk(KERN_INFO "fuse init (API version %i.%i)\n",
1202                FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1203
1204         INIT_LIST_HEAD(&fuse_conn_list);
1205         res = fuse_fs_init();
1206         if (res)
1207                 goto err;
1208
1209         res = fuse_dev_init();
1210         if (res)
1211                 goto err_fs_cleanup;
1212
1213         res = fuse_sysfs_init();
1214         if (res)
1215                 goto err_dev_cleanup;
1216
1217         res = fuse_ctl_init();
1218         if (res)
1219                 goto err_sysfs_cleanup;
1220
1221         sanitize_global_limit(&max_user_bgreq);
1222         sanitize_global_limit(&max_user_congthresh);
1223
1224         return 0;
1225
1226  err_sysfs_cleanup:
1227         fuse_sysfs_cleanup();
1228  err_dev_cleanup:
1229         fuse_dev_cleanup();
1230  err_fs_cleanup:
1231         fuse_fs_cleanup();
1232  err:
1233         return res;
1234 }
1235
1236 static void __exit fuse_exit(void)
1237 {
1238         printk(KERN_DEBUG "fuse exit\n");
1239
1240         fuse_ctl_cleanup();
1241         fuse_sysfs_cleanup();
1242         fuse_fs_cleanup();
1243         fuse_dev_cleanup();
1244 }
1245
1246 module_init(fuse_init);
1247 module_exit(fuse_exit);