linux/fs/fuse/inode.c
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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
  24MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
  25MODULE_DESCRIPTION("Filesystem in Userspace");
  26MODULE_LICENSE("GPL");
  27
  28static struct kmem_cache *fuse_inode_cachep;
  29struct list_head fuse_conn_list;
  30DEFINE_MUTEX(fuse_mutex);
  31
  32static int set_global_limit(const char *val, struct kernel_param *kp);
  33
  34unsigned max_user_bgreq;
  35module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
  36                  &max_user_bgreq, 0644);
  37__MODULE_PARM_TYPE(max_user_bgreq, "uint");
  38MODULE_PARM_DESC(max_user_bgreq,
  39 "Global limit for the maximum number of backgrounded requests an "
  40 "unprivileged user can set");
  41
  42unsigned max_user_congthresh;
  43module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
  44                  &max_user_congthresh, 0644);
  45__MODULE_PARM_TYPE(max_user_congthresh, "uint");
  46MODULE_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
  60struct fuse_mount_data {
  61        int fd;
  62        unsigned rootmode;
  63        kuid_t user_id;
  64        kgid_t group_id;
  65        unsigned fd_present:1;
  66        unsigned rootmode_present:1;
  67        unsigned user_id_present:1;
  68        unsigned group_id_present:1;
  69        unsigned flags;
  70        unsigned max_read;
  71        unsigned blksize;
  72};
  73
  74struct fuse_forget_link *fuse_alloc_forget(void)
  75{
  76        return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL);
  77}
  78
  79static struct inode *fuse_alloc_inode(struct super_block *sb)
  80{
  81        struct inode *inode;
  82        struct fuse_inode *fi;
  83
  84        inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
  85        if (!inode)
  86                return NULL;
  87
  88        fi = get_fuse_inode(inode);
  89        fi->i_time = 0;
  90        fi->nodeid = 0;
  91        fi->nlookup = 0;
  92        fi->attr_version = 0;
  93        fi->writectr = 0;
  94        fi->orig_ino = 0;
  95        fi->state = 0;
  96        INIT_LIST_HEAD(&fi->write_files);
  97        INIT_LIST_HEAD(&fi->queued_writes);
  98        INIT_LIST_HEAD(&fi->writepages);
  99        init_waitqueue_head(&fi->page_waitq);
 100        fi->forget = fuse_alloc_forget();
 101        if (!fi->forget) {
 102                kmem_cache_free(fuse_inode_cachep, inode);
 103                return NULL;
 104        }
 105
 106        return inode;
 107}
 108
 109static void fuse_i_callback(struct rcu_head *head)
 110{
 111        struct inode *inode = container_of(head, struct inode, i_rcu);
 112        kmem_cache_free(fuse_inode_cachep, inode);
 113}
 114
 115static void fuse_destroy_inode(struct inode *inode)
 116{
 117        struct fuse_inode *fi = get_fuse_inode(inode);
 118        BUG_ON(!list_empty(&fi->write_files));
 119        BUG_ON(!list_empty(&fi->queued_writes));
 120        kfree(fi->forget);
 121        call_rcu(&inode->i_rcu, fuse_i_callback);
 122}
 123
 124static void fuse_evict_inode(struct inode *inode)
 125{
 126        truncate_inode_pages_final(&inode->i_data);
 127        clear_inode(inode);
 128        if (inode->i_sb->s_flags & MS_ACTIVE) {
 129                struct fuse_conn *fc = get_fuse_conn(inode);
 130                struct fuse_inode *fi = get_fuse_inode(inode);
 131                fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
 132                fi->forget = NULL;
 133        }
 134}
 135
 136static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
 137{
 138        sync_filesystem(sb);
 139        if (*flags & MS_MANDLOCK)
 140                return -EINVAL;
 141
 142        return 0;
 143}
 144
 145/*
 146 * ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
 147 * so that it will fit.
 148 */
 149static ino_t fuse_squash_ino(u64 ino64)
 150{
 151        ino_t ino = (ino_t) ino64;
 152        if (sizeof(ino_t) < sizeof(u64))
 153                ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;
 154        return ino;
 155}
 156
 157void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 158                                   u64 attr_valid)
 159{
 160        struct fuse_conn *fc = get_fuse_conn(inode);
 161        struct fuse_inode *fi = get_fuse_inode(inode);
 162
 163        fi->attr_version = ++fc->attr_version;
 164        fi->i_time = attr_valid;
 165
 166        inode->i_ino     = fuse_squash_ino(attr->ino);
 167        inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
 168        set_nlink(inode, attr->nlink);
 169        inode->i_uid     = make_kuid(&init_user_ns, attr->uid);
 170        inode->i_gid     = make_kgid(&init_user_ns, attr->gid);
 171        inode->i_blocks  = attr->blocks;
 172        inode->i_atime.tv_sec   = attr->atime;
 173        inode->i_atime.tv_nsec  = attr->atimensec;
 174        /* mtime from server may be stale due to local buffered write */
 175        if (!fc->writeback_cache || !S_ISREG(inode->i_mode)) {
 176                inode->i_mtime.tv_sec   = attr->mtime;
 177                inode->i_mtime.tv_nsec  = attr->mtimensec;
 178                inode->i_ctime.tv_sec   = attr->ctime;
 179                inode->i_ctime.tv_nsec  = attr->ctimensec;
 180        }
 181
 182        if (attr->blksize != 0)
 183                inode->i_blkbits = ilog2(attr->blksize);
 184        else
 185                inode->i_blkbits = inode->i_sb->s_blocksize_bits;
 186
 187        /*
 188         * Don't set the sticky bit in i_mode, unless we want the VFS
 189         * to check permissions.  This prevents failures due to the
 190         * check in may_delete().
 191         */
 192        fi->orig_i_mode = inode->i_mode;
 193        if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
 194                inode->i_mode &= ~S_ISVTX;
 195
 196        fi->orig_ino = attr->ino;
 197}
 198
 199void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 200                            u64 attr_valid, u64 attr_version)
 201{
 202        struct fuse_conn *fc = get_fuse_conn(inode);
 203        struct fuse_inode *fi = get_fuse_inode(inode);
 204        bool is_wb = fc->writeback_cache;
 205        loff_t oldsize;
 206        struct timespec old_mtime;
 207
 208        spin_lock(&fc->lock);
 209        if ((attr_version != 0 && fi->attr_version > attr_version) ||
 210            test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
 211                spin_unlock(&fc->lock);
 212                return;
 213        }
 214
 215        old_mtime = inode->i_mtime;
 216        fuse_change_attributes_common(inode, attr, attr_valid);
 217
 218        oldsize = inode->i_size;
 219        /*
 220         * In case of writeback_cache enabled, the cached writes beyond EOF
 221         * extend local i_size without keeping userspace server in sync. So,
 222         * attr->size coming from server can be stale. We cannot trust it.
 223         */
 224        if (!is_wb || !S_ISREG(inode->i_mode))
 225                i_size_write(inode, attr->size);
 226        spin_unlock(&fc->lock);
 227
 228        if (!is_wb && S_ISREG(inode->i_mode)) {
 229                bool inval = false;
 230
 231                if (oldsize != attr->size) {
 232                        truncate_pagecache(inode, attr->size);
 233                        inval = true;
 234                } else if (fc->auto_inval_data) {
 235                        struct timespec new_mtime = {
 236                                .tv_sec = attr->mtime,
 237                                .tv_nsec = attr->mtimensec,
 238                        };
 239
 240                        /*
 241                         * Auto inval mode also checks and invalidates if mtime
 242                         * has changed.
 243                         */
 244                        if (!timespec_equal(&old_mtime, &new_mtime))
 245                                inval = true;
 246                }
 247
 248                if (inval)
 249                        invalidate_inode_pages2(inode->i_mapping);
 250        }
 251}
 252
 253static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 254{
 255        inode->i_mode = attr->mode & S_IFMT;
 256        inode->i_size = attr->size;
 257        inode->i_mtime.tv_sec  = attr->mtime;
 258        inode->i_mtime.tv_nsec = attr->mtimensec;
 259        inode->i_ctime.tv_sec  = attr->ctime;
 260        inode->i_ctime.tv_nsec = attr->ctimensec;
 261        if (S_ISREG(inode->i_mode)) {
 262                fuse_init_common(inode);
 263                fuse_init_file_inode(inode);
 264        } else if (S_ISDIR(inode->i_mode))
 265                fuse_init_dir(inode);
 266        else if (S_ISLNK(inode->i_mode))
 267                fuse_init_symlink(inode);
 268        else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 269                 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 270                fuse_init_common(inode);
 271                init_special_inode(inode, inode->i_mode,
 272                                   new_decode_dev(attr->rdev));
 273        } else
 274                BUG();
 275}
 276
 277int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 278{
 279        u64 nodeid = *(u64 *) _nodeidp;
 280        if (get_node_id(inode) == nodeid)
 281                return 1;
 282        else
 283                return 0;
 284}
 285
 286static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 287{
 288        u64 nodeid = *(u64 *) _nodeidp;
 289        get_fuse_inode(inode)->nodeid = nodeid;
 290        return 0;
 291}
 292
 293struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 294                        int generation, struct fuse_attr *attr,
 295                        u64 attr_valid, u64 attr_version)
 296{
 297        struct inode *inode;
 298        struct fuse_inode *fi;
 299        struct fuse_conn *fc = get_fuse_conn_super(sb);
 300
 301 retry:
 302        inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 303        if (!inode)
 304                return NULL;
 305
 306        if ((inode->i_state & I_NEW)) {
 307                inode->i_flags |= S_NOATIME;
 308                if (!fc->writeback_cache || !S_ISREG(attr->mode))
 309                        inode->i_flags |= S_NOCMTIME;
 310                inode->i_generation = generation;
 311                inode->i_data.backing_dev_info = &fc->bdi;
 312                fuse_init_inode(inode, attr);
 313                unlock_new_inode(inode);
 314        } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 315                /* Inode has changed type, any I/O on the old should fail */
 316                make_bad_inode(inode);
 317                iput(inode);
 318                goto retry;
 319        }
 320
 321        fi = get_fuse_inode(inode);
 322        spin_lock(&fc->lock);
 323        fi->nlookup++;
 324        spin_unlock(&fc->lock);
 325        fuse_change_attributes(inode, attr, attr_valid, attr_version);
 326
 327        return inode;
 328}
 329
 330int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
 331                             loff_t offset, loff_t len)
 332{
 333        struct inode *inode;
 334        pgoff_t pg_start;
 335        pgoff_t pg_end;
 336
 337        inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
 338        if (!inode)
 339                return -ENOENT;
 340
 341        fuse_invalidate_attr(inode);
 342        if (offset >= 0) {
 343                pg_start = offset >> PAGE_CACHE_SHIFT;
 344                if (len <= 0)
 345                        pg_end = -1;
 346                else
 347                        pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
 348                invalidate_inode_pages2_range(inode->i_mapping,
 349                                              pg_start, pg_end);
 350        }
 351        iput(inode);
 352        return 0;
 353}
 354
 355static void fuse_umount_begin(struct super_block *sb)
 356{
 357        fuse_abort_conn(get_fuse_conn_super(sb));
 358}
 359
 360static void fuse_send_destroy(struct fuse_conn *fc)
 361{
 362        struct fuse_req *req = fc->destroy_req;
 363        if (req && fc->conn_init) {
 364                fc->destroy_req = NULL;
 365                req->in.h.opcode = FUSE_DESTROY;
 366                req->force = 1;
 367                req->background = 0;
 368                fuse_request_send(fc, req);
 369                fuse_put_request(fc, req);
 370        }
 371}
 372
 373static void fuse_bdi_destroy(struct fuse_conn *fc)
 374{
 375        if (fc->bdi_initialized)
 376                bdi_destroy(&fc->bdi);
 377}
 378
 379static void fuse_put_super(struct super_block *sb)
 380{
 381        struct fuse_conn *fc = get_fuse_conn_super(sb);
 382
 383        fuse_send_destroy(fc);
 384
 385        fuse_abort_conn(fc);
 386        mutex_lock(&fuse_mutex);
 387        list_del(&fc->entry);
 388        fuse_ctl_remove_conn(fc);
 389        mutex_unlock(&fuse_mutex);
 390        fuse_bdi_destroy(fc);
 391
 392        fuse_conn_put(fc);
 393}
 394
 395static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
 396{
 397        stbuf->f_type    = FUSE_SUPER_MAGIC;
 398        stbuf->f_bsize   = attr->bsize;
 399        stbuf->f_frsize  = attr->frsize;
 400        stbuf->f_blocks  = attr->blocks;
 401        stbuf->f_bfree   = attr->bfree;
 402        stbuf->f_bavail  = attr->bavail;
 403        stbuf->f_files   = attr->files;
 404        stbuf->f_ffree   = attr->ffree;
 405        stbuf->f_namelen = attr->namelen;
 406        /* fsid is left zero */
 407}
 408
 409static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 410{
 411        struct super_block *sb = dentry->d_sb;
 412        struct fuse_conn *fc = get_fuse_conn_super(sb);
 413        FUSE_ARGS(args);
 414        struct fuse_statfs_out outarg;
 415        int err;
 416
 417        if (!fuse_allow_current_process(fc)) {
 418                buf->f_type = FUSE_SUPER_MAGIC;
 419                return 0;
 420        }
 421
 422        memset(&outarg, 0, sizeof(outarg));
 423        args.in.numargs = 0;
 424        args.in.h.opcode = FUSE_STATFS;
 425        args.in.h.nodeid = get_node_id(dentry->d_inode);
 426        args.out.numargs = 1;
 427        args.out.args[0].size = sizeof(outarg);
 428        args.out.args[0].value = &outarg;
 429        err = fuse_simple_request(fc, &args);
 430        if (!err)
 431                convert_fuse_statfs(buf, &outarg.st);
 432        return err;
 433}
 434
 435enum {
 436        OPT_FD,
 437        OPT_ROOTMODE,
 438        OPT_USER_ID,
 439        OPT_GROUP_ID,
 440        OPT_DEFAULT_PERMISSIONS,
 441        OPT_ALLOW_OTHER,
 442        OPT_MAX_READ,
 443        OPT_BLKSIZE,
 444        OPT_ERR
 445};
 446
 447static const match_table_t tokens = {
 448        {OPT_FD,                        "fd=%u"},
 449        {OPT_ROOTMODE,                  "rootmode=%o"},
 450        {OPT_USER_ID,                   "user_id=%u"},
 451        {OPT_GROUP_ID,                  "group_id=%u"},
 452        {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
 453        {OPT_ALLOW_OTHER,               "allow_other"},
 454        {OPT_MAX_READ,                  "max_read=%u"},
 455        {OPT_BLKSIZE,                   "blksize=%u"},
 456        {OPT_ERR,                       NULL}
 457};
 458
 459static int fuse_match_uint(substring_t *s, unsigned int *res)
 460{
 461        int err = -ENOMEM;
 462        char *buf = match_strdup(s);
 463        if (buf) {
 464                err = kstrtouint(buf, 10, res);
 465                kfree(buf);
 466        }
 467        return err;
 468}
 469
 470static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
 471{
 472        char *p;
 473        memset(d, 0, sizeof(struct fuse_mount_data));
 474        d->max_read = ~0;
 475        d->blksize = FUSE_DEFAULT_BLKSIZE;
 476
 477        while ((p = strsep(&opt, ",")) != NULL) {
 478                int token;
 479                int value;
 480                unsigned uv;
 481                substring_t args[MAX_OPT_ARGS];
 482                if (!*p)
 483                        continue;
 484
 485                token = match_token(p, tokens, args);
 486                switch (token) {
 487                case OPT_FD:
 488                        if (match_int(&args[0], &value))
 489                                return 0;
 490                        d->fd = value;
 491                        d->fd_present = 1;
 492                        break;
 493
 494                case OPT_ROOTMODE:
 495                        if (match_octal(&args[0], &value))
 496                                return 0;
 497                        if (!fuse_valid_type(value))
 498                                return 0;
 499                        d->rootmode = value;
 500                        d->rootmode_present = 1;
 501                        break;
 502
 503                case OPT_USER_ID:
 504                        if (fuse_match_uint(&args[0], &uv))
 505                                return 0;
 506                        d->user_id = make_kuid(current_user_ns(), uv);
 507                        if (!uid_valid(d->user_id))
 508                                return 0;
 509                        d->user_id_present = 1;
 510                        break;
 511
 512                case OPT_GROUP_ID:
 513                        if (fuse_match_uint(&args[0], &uv))
 514                                return 0;
 515                        d->group_id = make_kgid(current_user_ns(), uv);
 516                        if (!gid_valid(d->group_id))
 517                                return 0;
 518                        d->group_id_present = 1;
 519                        break;
 520
 521                case OPT_DEFAULT_PERMISSIONS:
 522                        d->flags |= FUSE_DEFAULT_PERMISSIONS;
 523                        break;
 524
 525                case OPT_ALLOW_OTHER:
 526                        d->flags |= FUSE_ALLOW_OTHER;
 527                        break;
 528
 529                case OPT_MAX_READ:
 530                        if (match_int(&args[0], &value))
 531                                return 0;
 532                        d->max_read = value;
 533                        break;
 534
 535                case OPT_BLKSIZE:
 536                        if (!is_bdev || match_int(&args[0], &value))
 537                                return 0;
 538                        d->blksize = value;
 539                        break;
 540
 541                default:
 542                        return 0;
 543                }
 544        }
 545
 546        if (!d->fd_present || !d->rootmode_present ||
 547            !d->user_id_present || !d->group_id_present)
 548                return 0;
 549
 550        return 1;
 551}
 552
 553static int fuse_show_options(struct seq_file *m, struct dentry *root)
 554{
 555        struct super_block *sb = root->d_sb;
 556        struct fuse_conn *fc = get_fuse_conn_super(sb);
 557
 558        seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id));
 559        seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id));
 560        if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
 561                seq_puts(m, ",default_permissions");
 562        if (fc->flags & FUSE_ALLOW_OTHER)
 563                seq_puts(m, ",allow_other");
 564        if (fc->max_read != ~0)
 565                seq_printf(m, ",max_read=%u", fc->max_read);
 566        if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
 567                seq_printf(m, ",blksize=%lu", sb->s_blocksize);
 568        return 0;
 569}
 570
 571void fuse_conn_init(struct fuse_conn *fc)
 572{
 573        memset(fc, 0, sizeof(*fc));
 574        spin_lock_init(&fc->lock);
 575        init_rwsem(&fc->killsb);
 576        atomic_set(&fc->count, 1);
 577        init_waitqueue_head(&fc->waitq);
 578        init_waitqueue_head(&fc->blocked_waitq);
 579        init_waitqueue_head(&fc->reserved_req_waitq);
 580        INIT_LIST_HEAD(&fc->pending);
 581        INIT_LIST_HEAD(&fc->processing);
 582        INIT_LIST_HEAD(&fc->io);
 583        INIT_LIST_HEAD(&fc->interrupts);
 584        INIT_LIST_HEAD(&fc->bg_queue);
 585        INIT_LIST_HEAD(&fc->entry);
 586        fc->forget_list_tail = &fc->forget_list_head;
 587        atomic_set(&fc->num_waiting, 0);
 588        fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
 589        fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
 590        fc->khctr = 0;
 591        fc->polled_files = RB_ROOT;
 592        fc->reqctr = 0;
 593        fc->blocked = 0;
 594        fc->initialized = 0;
 595        fc->attr_version = 1;
 596        get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 597}
 598EXPORT_SYMBOL_GPL(fuse_conn_init);
 599
 600void fuse_conn_put(struct fuse_conn *fc)
 601{
 602        if (atomic_dec_and_test(&fc->count)) {
 603                if (fc->destroy_req)
 604                        fuse_request_free(fc->destroy_req);
 605                fc->release(fc);
 606        }
 607}
 608EXPORT_SYMBOL_GPL(fuse_conn_put);
 609
 610struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
 611{
 612        atomic_inc(&fc->count);
 613        return fc;
 614}
 615EXPORT_SYMBOL_GPL(fuse_conn_get);
 616
 617static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
 618{
 619        struct fuse_attr attr;
 620        memset(&attr, 0, sizeof(attr));
 621
 622        attr.mode = mode;
 623        attr.ino = FUSE_ROOT_ID;
 624        attr.nlink = 1;
 625        return fuse_iget(sb, 1, 0, &attr, 0, 0);
 626}
 627
 628struct fuse_inode_handle {
 629        u64 nodeid;
 630        u32 generation;
 631};
 632
 633static struct dentry *fuse_get_dentry(struct super_block *sb,
 634                                      struct fuse_inode_handle *handle)
 635{
 636        struct fuse_conn *fc = get_fuse_conn_super(sb);
 637        struct inode *inode;
 638        struct dentry *entry;
 639        int err = -ESTALE;
 640
 641        if (handle->nodeid == 0)
 642                goto out_err;
 643
 644        inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
 645        if (!inode) {
 646                struct fuse_entry_out outarg;
 647                struct qstr name;
 648
 649                if (!fc->export_support)
 650                        goto out_err;
 651
 652                name.len = 1;
 653                name.name = ".";
 654                err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
 655                                       &inode);
 656                if (err && err != -ENOENT)
 657                        goto out_err;
 658                if (err || !inode) {
 659                        err = -ESTALE;
 660                        goto out_err;
 661                }
 662                err = -EIO;
 663                if (get_node_id(inode) != handle->nodeid)
 664                        goto out_iput;
 665        }
 666        err = -ESTALE;
 667        if (inode->i_generation != handle->generation)
 668                goto out_iput;
 669
 670        entry = d_obtain_alias(inode);
 671        if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
 672                fuse_invalidate_entry_cache(entry);
 673
 674        return entry;
 675
 676 out_iput:
 677        iput(inode);
 678 out_err:
 679        return ERR_PTR(err);
 680}
 681
 682static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
 683                           struct inode *parent)
 684{
 685        int len = parent ? 6 : 3;
 686        u64 nodeid;
 687        u32 generation;
 688
 689        if (*max_len < len) {
 690                *max_len = len;
 691                return  FILEID_INVALID;
 692        }
 693
 694        nodeid = get_fuse_inode(inode)->nodeid;
 695        generation = inode->i_generation;
 696
 697        fh[0] = (u32)(nodeid >> 32);
 698        fh[1] = (u32)(nodeid & 0xffffffff);
 699        fh[2] = generation;
 700
 701        if (parent) {
 702                nodeid = get_fuse_inode(parent)->nodeid;
 703                generation = parent->i_generation;
 704
 705                fh[3] = (u32)(nodeid >> 32);
 706                fh[4] = (u32)(nodeid & 0xffffffff);
 707                fh[5] = generation;
 708        }
 709
 710        *max_len = len;
 711        return parent ? 0x82 : 0x81;
 712}
 713
 714static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
 715                struct fid *fid, int fh_len, int fh_type)
 716{
 717        struct fuse_inode_handle handle;
 718
 719        if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
 720                return NULL;
 721
 722        handle.nodeid = (u64) fid->raw[0] << 32;
 723        handle.nodeid |= (u64) fid->raw[1];
 724        handle.generation = fid->raw[2];
 725        return fuse_get_dentry(sb, &handle);
 726}
 727
 728static struct dentry *fuse_fh_to_parent(struct super_block *sb,
 729                struct fid *fid, int fh_len, int fh_type)
 730{
 731        struct fuse_inode_handle parent;
 732
 733        if (fh_type != 0x82 || fh_len < 6)
 734                return NULL;
 735
 736        parent.nodeid = (u64) fid->raw[3] << 32;
 737        parent.nodeid |= (u64) fid->raw[4];
 738        parent.generation = fid->raw[5];
 739        return fuse_get_dentry(sb, &parent);
 740}
 741
 742static struct dentry *fuse_get_parent(struct dentry *child)
 743{
 744        struct inode *child_inode = child->d_inode;
 745        struct fuse_conn *fc = get_fuse_conn(child_inode);
 746        struct inode *inode;
 747        struct dentry *parent;
 748        struct fuse_entry_out outarg;
 749        struct qstr name;
 750        int err;
 751
 752        if (!fc->export_support)
 753                return ERR_PTR(-ESTALE);
 754
 755        name.len = 2;
 756        name.name = "..";
 757        err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
 758                               &name, &outarg, &inode);
 759        if (err) {
 760                if (err == -ENOENT)
 761                        return ERR_PTR(-ESTALE);
 762                return ERR_PTR(err);
 763        }
 764
 765        parent = d_obtain_alias(inode);
 766        if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
 767                fuse_invalidate_entry_cache(parent);
 768
 769        return parent;
 770}
 771
 772static const struct export_operations fuse_export_operations = {
 773        .fh_to_dentry   = fuse_fh_to_dentry,
 774        .fh_to_parent   = fuse_fh_to_parent,
 775        .encode_fh      = fuse_encode_fh,
 776        .get_parent     = fuse_get_parent,
 777};
 778
 779static const struct super_operations fuse_super_operations = {
 780        .alloc_inode    = fuse_alloc_inode,
 781        .destroy_inode  = fuse_destroy_inode,
 782        .evict_inode    = fuse_evict_inode,
 783        .write_inode    = fuse_write_inode,
 784        .drop_inode     = generic_delete_inode,
 785        .remount_fs     = fuse_remount_fs,
 786        .put_super      = fuse_put_super,
 787        .umount_begin   = fuse_umount_begin,
 788        .statfs         = fuse_statfs,
 789        .show_options   = fuse_show_options,
 790};
 791
 792static void sanitize_global_limit(unsigned *limit)
 793{
 794        if (*limit == 0)
 795                *limit = ((totalram_pages << PAGE_SHIFT) >> 13) /
 796                         sizeof(struct fuse_req);
 797
 798        if (*limit >= 1 << 16)
 799                *limit = (1 << 16) - 1;
 800}
 801
 802static int set_global_limit(const char *val, struct kernel_param *kp)
 803{
 804        int rv;
 805
 806        rv = param_set_uint(val, kp);
 807        if (rv)
 808                return rv;
 809
 810        sanitize_global_limit((unsigned *)kp->arg);
 811
 812        return 0;
 813}
 814
 815static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 816{
 817        int cap_sys_admin = capable(CAP_SYS_ADMIN);
 818
 819        if (arg->minor < 13)
 820                return;
 821
 822        sanitize_global_limit(&max_user_bgreq);
 823        sanitize_global_limit(&max_user_congthresh);
 824
 825        if (arg->max_background) {
 826                fc->max_background = arg->max_background;
 827
 828                if (!cap_sys_admin && fc->max_background > max_user_bgreq)
 829                        fc->max_background = max_user_bgreq;
 830        }
 831        if (arg->congestion_threshold) {
 832                fc->congestion_threshold = arg->congestion_threshold;
 833
 834                if (!cap_sys_admin &&
 835                    fc->congestion_threshold > max_user_congthresh)
 836                        fc->congestion_threshold = max_user_congthresh;
 837        }
 838}
 839
 840static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 841{
 842        struct fuse_init_out *arg = &req->misc.init_out;
 843
 844        if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
 845                fc->conn_error = 1;
 846        else {
 847                unsigned long ra_pages;
 848
 849                process_init_limits(fc, arg);
 850
 851                if (arg->minor >= 6) {
 852                        ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
 853                        if (arg->flags & FUSE_ASYNC_READ)
 854                                fc->async_read = 1;
 855                        if (!(arg->flags & FUSE_POSIX_LOCKS))
 856                                fc->no_lock = 1;
 857                        if (arg->minor >= 17) {
 858                                if (!(arg->flags & FUSE_FLOCK_LOCKS))
 859                                        fc->no_flock = 1;
 860                        } else {
 861                                if (!(arg->flags & FUSE_POSIX_LOCKS))
 862                                        fc->no_flock = 1;
 863                        }
 864                        if (arg->flags & FUSE_ATOMIC_O_TRUNC)
 865                                fc->atomic_o_trunc = 1;
 866                        if (arg->minor >= 9) {
 867                                /* LOOKUP has dependency on proto version */
 868                                if (arg->flags & FUSE_EXPORT_SUPPORT)
 869                                        fc->export_support = 1;
 870                        }
 871                        if (arg->flags & FUSE_BIG_WRITES)
 872                                fc->big_writes = 1;
 873                        if (arg->flags & FUSE_DONT_MASK)
 874                                fc->dont_mask = 1;
 875                        if (arg->flags & FUSE_AUTO_INVAL_DATA)
 876                                fc->auto_inval_data = 1;
 877                        if (arg->flags & FUSE_DO_READDIRPLUS) {
 878                                fc->do_readdirplus = 1;
 879                                if (arg->flags & FUSE_READDIRPLUS_AUTO)
 880                                        fc->readdirplus_auto = 1;
 881                        }
 882                        if (arg->flags & FUSE_ASYNC_DIO)
 883                                fc->async_dio = 1;
 884                        if (arg->flags & FUSE_WRITEBACK_CACHE)
 885                                fc->writeback_cache = 1;
 886                        if (arg->time_gran && arg->time_gran <= 1000000000)
 887                                fc->sb->s_time_gran = arg->time_gran;
 888                } else {
 889                        ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 890                        fc->no_lock = 1;
 891                        fc->no_flock = 1;
 892                }
 893
 894                fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
 895                fc->minor = arg->minor;
 896                fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
 897                fc->max_write = max_t(unsigned, 4096, fc->max_write);
 898                fc->conn_init = 1;
 899        }
 900        fuse_set_initialized(fc);
 901        wake_up_all(&fc->blocked_waitq);
 902}
 903
 904static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
 905{
 906        struct fuse_init_in *arg = &req->misc.init_in;
 907
 908        arg->major = FUSE_KERNEL_VERSION;
 909        arg->minor = FUSE_KERNEL_MINOR_VERSION;
 910        arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
 911        arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
 912                FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
 913                FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
 914                FUSE_FLOCK_LOCKS | FUSE_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
 915                FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
 916                FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT;
 917        req->in.h.opcode = FUSE_INIT;
 918        req->in.numargs = 1;
 919        req->in.args[0].size = sizeof(*arg);
 920        req->in.args[0].value = arg;
 921        req->out.numargs = 1;
 922        /* Variable length argument used for backward compatibility
 923           with interface version < 7.5.  Rest of init_out is zeroed
 924           by do_get_request(), so a short reply is not a problem */
 925        req->out.argvar = 1;
 926        req->out.args[0].size = sizeof(struct fuse_init_out);
 927        req->out.args[0].value = &req->misc.init_out;
 928        req->end = process_init_reply;
 929        fuse_request_send_background(fc, req);
 930}
 931
 932static void fuse_free_conn(struct fuse_conn *fc)
 933{
 934        kfree_rcu(fc, rcu);
 935}
 936
 937static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
 938{
 939        int err;
 940
 941        fc->bdi.name = "fuse";
 942        fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 943        /* fuse does it's own writeback accounting */
 944        fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;
 945
 946        err = bdi_init(&fc->bdi);
 947        if (err)
 948                return err;
 949
 950        fc->bdi_initialized = 1;
 951
 952        if (sb->s_bdev) {
 953                err =  bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",
 954                                    MAJOR(fc->dev), MINOR(fc->dev));
 955        } else {
 956                err = bdi_register_dev(&fc->bdi, fc->dev);
 957        }
 958
 959        if (err)
 960                return err;
 961
 962        /*
 963         * For a single fuse filesystem use max 1% of dirty +
 964         * writeback threshold.
 965         *
 966         * This gives about 1M of write buffer for memory maps on a
 967         * machine with 1G and 10% dirty_ratio, which should be more
 968         * than enough.
 969         *
 970         * Privileged users can raise it by writing to
 971         *
 972         *    /sys/class/bdi/<bdi>/max_ratio
 973         */
 974        bdi_set_max_ratio(&fc->bdi, 1);
 975
 976        return 0;
 977}
 978
 979static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 980{
 981        struct fuse_conn *fc;
 982        struct inode *root;
 983        struct fuse_mount_data d;
 984        struct file *file;
 985        struct dentry *root_dentry;
 986        struct fuse_req *init_req;
 987        int err;
 988        int is_bdev = sb->s_bdev != NULL;
 989
 990        err = -EINVAL;
 991        if (sb->s_flags & MS_MANDLOCK)
 992                goto err;
 993
 994        sb->s_flags &= ~(MS_NOSEC | MS_I_VERSION);
 995
 996        if (!parse_fuse_opt(data, &d, is_bdev))
 997                goto err;
 998
 999        if (is_bdev) {
1000#ifdef CONFIG_BLOCK
1001                err = -EINVAL;
1002                if (!sb_set_blocksize(sb, d.blksize))
1003                        goto err;
1004#endif
1005        } else {
1006                sb->s_blocksize = PAGE_CACHE_SIZE;
1007                sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
1008        }
1009        sb->s_magic = FUSE_SUPER_MAGIC;
1010        sb->s_op = &fuse_super_operations;
1011        sb->s_maxbytes = MAX_LFS_FILESIZE;
1012        sb->s_time_gran = 1;
1013        sb->s_export_op = &fuse_export_operations;
1014
1015        file = fget(d.fd);
1016        err = -EINVAL;
1017        if (!file)
1018                goto err;
1019
1020        if ((file->f_op != &fuse_dev_operations) ||
1021            (file->f_cred->user_ns != &init_user_ns))
1022                goto err_fput;
1023
1024        fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1025        err = -ENOMEM;
1026        if (!fc)
1027                goto err_fput;
1028
1029        fuse_conn_init(fc);
1030
1031        fc->dev = sb->s_dev;
1032        fc->sb = sb;
1033        err = fuse_bdi_init(fc, sb);
1034        if (err)
1035                goto err_put_conn;
1036
1037        sb->s_bdi = &fc->bdi;
1038
1039        /* Handle umasking inside the fuse code */
1040        if (sb->s_flags & MS_POSIXACL)
1041                fc->dont_mask = 1;
1042        sb->s_flags |= MS_POSIXACL;
1043
1044        fc->release = fuse_free_conn;
1045        fc->flags = d.flags;
1046        fc->user_id = d.user_id;
1047        fc->group_id = d.group_id;
1048        fc->max_read = max_t(unsigned, 4096, d.max_read);
1049
1050        /* Used by get_root_inode() */
1051        sb->s_fs_info = fc;
1052
1053        err = -ENOMEM;
1054        root = fuse_get_root_inode(sb, d.rootmode);
1055        root_dentry = d_make_root(root);
1056        if (!root_dentry)
1057                goto err_put_conn;
1058        /* only now - we want root dentry with NULL ->d_op */
1059        sb->s_d_op = &fuse_dentry_operations;
1060
1061        init_req = fuse_request_alloc(0);
1062        if (!init_req)
1063                goto err_put_root;
1064        init_req->background = 1;
1065
1066        if (is_bdev) {
1067                fc->destroy_req = fuse_request_alloc(0);
1068                if (!fc->destroy_req)
1069                        goto err_free_init_req;
1070        }
1071
1072        mutex_lock(&fuse_mutex);
1073        err = -EINVAL;
1074        if (file->private_data)
1075                goto err_unlock;
1076
1077        err = fuse_ctl_add_conn(fc);
1078        if (err)
1079                goto err_unlock;
1080
1081        list_add_tail(&fc->entry, &fuse_conn_list);
1082        sb->s_root = root_dentry;
1083        fc->connected = 1;
1084        file->private_data = fuse_conn_get(fc);
1085        mutex_unlock(&fuse_mutex);
1086        /*
1087         * atomic_dec_and_test() in fput() provides the necessary
1088         * memory barrier for file->private_data to be visible on all
1089         * CPUs after this
1090         */
1091        fput(file);
1092
1093        fuse_send_init(fc, init_req);
1094
1095        return 0;
1096
1097 err_unlock:
1098        mutex_unlock(&fuse_mutex);
1099 err_free_init_req:
1100        fuse_request_free(init_req);
1101 err_put_root:
1102        dput(root_dentry);
1103 err_put_conn:
1104        fuse_bdi_destroy(fc);
1105        fuse_conn_put(fc);
1106 err_fput:
1107        fput(file);
1108 err:
1109        return err;
1110}
1111
1112static struct dentry *fuse_mount(struct file_system_type *fs_type,
1113                       int flags, const char *dev_name,
1114                       void *raw_data)
1115{
1116        return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
1117}
1118
1119static void fuse_kill_sb_anon(struct super_block *sb)
1120{
1121        struct fuse_conn *fc = get_fuse_conn_super(sb);
1122
1123        if (fc) {
1124                down_write(&fc->killsb);
1125                fc->sb = NULL;
1126                up_write(&fc->killsb);
1127        }
1128
1129        kill_anon_super(sb);
1130}
1131
1132static struct file_system_type fuse_fs_type = {
1133        .owner          = THIS_MODULE,
1134        .name           = "fuse",
1135        .fs_flags       = FS_HAS_SUBTYPE,
1136        .mount          = fuse_mount,
1137        .kill_sb        = fuse_kill_sb_anon,
1138};
1139MODULE_ALIAS_FS("fuse");
1140
1141#ifdef CONFIG_BLOCK
1142static struct dentry *fuse_mount_blk(struct file_system_type *fs_type,
1143                           int flags, const char *dev_name,
1144                           void *raw_data)
1145{
1146        return mount_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super);
1147}
1148
1149static void fuse_kill_sb_blk(struct super_block *sb)
1150{
1151        struct fuse_conn *fc = get_fuse_conn_super(sb);
1152
1153        if (fc) {
1154                down_write(&fc->killsb);
1155                fc->sb = NULL;
1156                up_write(&fc->killsb);
1157        }
1158
1159        kill_block_super(sb);
1160}
1161
1162static struct file_system_type fuseblk_fs_type = {
1163        .owner          = THIS_MODULE,
1164        .name           = "fuseblk",
1165        .mount          = fuse_mount_blk,
1166        .kill_sb        = fuse_kill_sb_blk,
1167        .fs_flags       = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1168};
1169MODULE_ALIAS_FS("fuseblk");
1170
1171static inline int register_fuseblk(void)
1172{
1173        return register_filesystem(&fuseblk_fs_type);
1174}
1175
1176static inline void unregister_fuseblk(void)
1177{
1178        unregister_filesystem(&fuseblk_fs_type);
1179}
1180#else
1181static inline int register_fuseblk(void)
1182{
1183        return 0;
1184}
1185
1186static inline void unregister_fuseblk(void)
1187{
1188}
1189#endif
1190
1191static void fuse_inode_init_once(void *foo)
1192{
1193        struct inode *inode = foo;
1194
1195        inode_init_once(inode);
1196}
1197
1198static int __init fuse_fs_init(void)
1199{
1200        int err;
1201
1202        fuse_inode_cachep = kmem_cache_create("fuse_inode",
1203                                              sizeof(struct fuse_inode),
1204                                              0, SLAB_HWCACHE_ALIGN,
1205                                              fuse_inode_init_once);
1206        err = -ENOMEM;
1207        if (!fuse_inode_cachep)
1208                goto out;
1209
1210        err = register_fuseblk();
1211        if (err)
1212                goto out2;
1213
1214        err = register_filesystem(&fuse_fs_type);
1215        if (err)
1216                goto out3;
1217
1218        return 0;
1219
1220 out3:
1221        unregister_fuseblk();
1222 out2:
1223        kmem_cache_destroy(fuse_inode_cachep);
1224 out:
1225        return err;
1226}
1227
1228static void fuse_fs_cleanup(void)
1229{
1230        unregister_filesystem(&fuse_fs_type);
1231        unregister_fuseblk();
1232
1233        /*
1234         * Make sure all delayed rcu free inodes are flushed before we
1235         * destroy cache.
1236         */
1237        rcu_barrier();
1238        kmem_cache_destroy(fuse_inode_cachep);
1239}
1240
1241static struct kobject *fuse_kobj;
1242static struct kobject *connections_kobj;
1243
1244static int fuse_sysfs_init(void)
1245{
1246        int err;
1247
1248        fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1249        if (!fuse_kobj) {
1250                err = -ENOMEM;
1251                goto out_err;
1252        }
1253
1254        connections_kobj = kobject_create_and_add("connections", fuse_kobj);
1255        if (!connections_kobj) {
1256                err = -ENOMEM;
1257                goto out_fuse_unregister;
1258        }
1259
1260        return 0;
1261
1262 out_fuse_unregister:
1263        kobject_put(fuse_kobj);
1264 out_err:
1265        return err;
1266}
1267
1268static void fuse_sysfs_cleanup(void)
1269{
1270        kobject_put(connections_kobj);
1271        kobject_put(fuse_kobj);
1272}
1273
1274static int __init fuse_init(void)
1275{
1276        int res;
1277
1278        printk(KERN_INFO "fuse init (API version %i.%i)\n",
1279               FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1280
1281        INIT_LIST_HEAD(&fuse_conn_list);
1282        res = fuse_fs_init();
1283        if (res)
1284                goto err;
1285
1286        res = fuse_dev_init();
1287        if (res)
1288                goto err_fs_cleanup;
1289
1290        res = fuse_sysfs_init();
1291        if (res)
1292                goto err_dev_cleanup;
1293
1294        res = fuse_ctl_init();
1295        if (res)
1296                goto err_sysfs_cleanup;
1297
1298        sanitize_global_limit(&max_user_bgreq);
1299        sanitize_global_limit(&max_user_congthresh);
1300
1301        return 0;
1302
1303 err_sysfs_cleanup:
1304        fuse_sysfs_cleanup();
1305 err_dev_cleanup:
1306        fuse_dev_cleanup();
1307 err_fs_cleanup:
1308        fuse_fs_cleanup();
1309 err:
1310        return res;
1311}
1312
1313static void __exit fuse_exit(void)
1314{
1315        printk(KERN_DEBUG "fuse exit\n");
1316
1317        fuse_ctl_cleanup();
1318        fuse_sysfs_cleanup();
1319        fuse_fs_cleanup();
1320        fuse_dev_cleanup();
1321}
1322
1323module_init(fuse_init);
1324module_exit(fuse_exit);
1325
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