linux/fs/namei.c
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   1/*
   2 *  linux/fs/namei.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7/*
   8 * Some corrections by tytso.
   9 */
  10
  11/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
  12 * lookup logic.
  13 */
  14/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
  15 */
  16
  17#include <linux/init.h>
  18#include <linux/module.h>
  19#include <linux/slab.h>
  20#include <linux/fs.h>
  21#include <linux/namei.h>
  22#include <linux/quotaops.h>
  23#include <linux/pagemap.h>
  24#include <linux/fsnotify.h>
  25#include <linux/personality.h>
  26#include <linux/security.h>
  27#include <linux/syscalls.h>
  28#include <linux/mount.h>
  29#include <linux/audit.h>
  30#include <linux/capability.h>
  31#include <linux/file.h>
  32#include <linux/fcntl.h>
  33#include <linux/device_cgroup.h>
  34#include <asm/uaccess.h>
  35
  36#define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
  37
  38/* [Feb-1997 T. Schoebel-Theuer]
  39 * Fundamental changes in the pathname lookup mechanisms (namei)
  40 * were necessary because of omirr.  The reason is that omirr needs
  41 * to know the _real_ pathname, not the user-supplied one, in case
  42 * of symlinks (and also when transname replacements occur).
  43 *
  44 * The new code replaces the old recursive symlink resolution with
  45 * an iterative one (in case of non-nested symlink chains).  It does
  46 * this with calls to <fs>_follow_link().
  47 * As a side effect, dir_namei(), _namei() and follow_link() are now 
  48 * replaced with a single function lookup_dentry() that can handle all 
  49 * the special cases of the former code.
  50 *
  51 * With the new dcache, the pathname is stored at each inode, at least as
  52 * long as the refcount of the inode is positive.  As a side effect, the
  53 * size of the dcache depends on the inode cache and thus is dynamic.
  54 *
  55 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
  56 * resolution to correspond with current state of the code.
  57 *
  58 * Note that the symlink resolution is not *completely* iterative.
  59 * There is still a significant amount of tail- and mid- recursion in
  60 * the algorithm.  Also, note that <fs>_readlink() is not used in
  61 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
  62 * may return different results than <fs>_follow_link().  Many virtual
  63 * filesystems (including /proc) exhibit this behavior.
  64 */
  65
  66/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
  67 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
  68 * and the name already exists in form of a symlink, try to create the new
  69 * name indicated by the symlink. The old code always complained that the
  70 * name already exists, due to not following the symlink even if its target
  71 * is nonexistent.  The new semantics affects also mknod() and link() when
  72 * the name is a symlink pointing to a non-existant name.
  73 *
  74 * I don't know which semantics is the right one, since I have no access
  75 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
  76 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
  77 * "old" one. Personally, I think the new semantics is much more logical.
  78 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
  79 * file does succeed in both HP-UX and SunOs, but not in Solaris
  80 * and in the old Linux semantics.
  81 */
  82
  83/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
  84 * semantics.  See the comments in "open_namei" and "do_link" below.
  85 *
  86 * [10-Sep-98 Alan Modra] Another symlink change.
  87 */
  88
  89/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
  90 *      inside the path - always follow.
  91 *      in the last component in creation/removal/renaming - never follow.
  92 *      if LOOKUP_FOLLOW passed - follow.
  93 *      if the pathname has trailing slashes - follow.
  94 *      otherwise - don't follow.
  95 * (applied in that order).
  96 *
  97 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
  98 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
  99 * During the 2.4 we need to fix the userland stuff depending on it -
 100 * hopefully we will be able to get rid of that wart in 2.5. So far only
 101 * XEmacs seems to be relying on it...
 102 */
 103/*
 104 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
 105 * implemented.  Let's see if raised priority of ->s_vfs_rename_mutex gives
 106 * any extra contention...
 107 */
 108
 109static int __link_path_walk(const char *name, struct nameidata *nd);
 110
 111/* In order to reduce some races, while at the same time doing additional
 112 * checking and hopefully speeding things up, we copy filenames to the
 113 * kernel data space before using them..
 114 *
 115 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
 116 * PATH_MAX includes the nul terminator --RR.
 117 */
 118static int do_getname(const char __user *filename, char *page)
 119{
 120        int retval;
 121        unsigned long len = PATH_MAX;
 122
 123        if (!segment_eq(get_fs(), KERNEL_DS)) {
 124                if ((unsigned long) filename >= TASK_SIZE)
 125                        return -EFAULT;
 126                if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
 127                        len = TASK_SIZE - (unsigned long) filename;
 128        }
 129
 130        retval = strncpy_from_user(page, filename, len);
 131        if (retval > 0) {
 132                if (retval < len)
 133                        return 0;
 134                return -ENAMETOOLONG;
 135        } else if (!retval)
 136                retval = -ENOENT;
 137        return retval;
 138}
 139
 140char * getname(const char __user * filename)
 141{
 142        char *tmp, *result;
 143
 144        result = ERR_PTR(-ENOMEM);
 145        tmp = __getname();
 146        if (tmp)  {
 147                int retval = do_getname(filename, tmp);
 148
 149                result = tmp;
 150                if (retval < 0) {
 151                        __putname(tmp);
 152                        result = ERR_PTR(retval);
 153                }
 154        }
 155        audit_getname(result);
 156        return result;
 157}
 158
 159#ifdef CONFIG_AUDITSYSCALL
 160void putname(const char *name)
 161{
 162        if (unlikely(!audit_dummy_context()))
 163                audit_putname(name);
 164        else
 165                __putname(name);
 166}
 167EXPORT_SYMBOL(putname);
 168#endif
 169
 170
 171/**
 172 * generic_permission  -  check for access rights on a Posix-like filesystem
 173 * @inode:      inode to check access rights for
 174 * @mask:       right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 175 * @check_acl:  optional callback to check for Posix ACLs
 176 *
 177 * Used to check for read/write/execute permissions on a file.
 178 * We use "fsuid" for this, letting us set arbitrary permissions
 179 * for filesystem access without changing the "normal" uids which
 180 * are used for other things..
 181 */
 182int generic_permission(struct inode *inode, int mask,
 183                int (*check_acl)(struct inode *inode, int mask))
 184{
 185        umode_t                 mode = inode->i_mode;
 186
 187        mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 188
 189        if (current->fsuid == inode->i_uid)
 190                mode >>= 6;
 191        else {
 192                if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
 193                        int error = check_acl(inode, mask);
 194                        if (error == -EACCES)
 195                                goto check_capabilities;
 196                        else if (error != -EAGAIN)
 197                                return error;
 198                }
 199
 200                if (in_group_p(inode->i_gid))
 201                        mode >>= 3;
 202        }
 203
 204        /*
 205         * If the DACs are ok we don't need any capability check.
 206         */
 207        if ((mask & ~mode) == 0)
 208                return 0;
 209
 210 check_capabilities:
 211        /*
 212         * Read/write DACs are always overridable.
 213         * Executable DACs are overridable if at least one exec bit is set.
 214         */
 215        if (!(mask & MAY_EXEC) ||
 216            (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
 217                if (capable(CAP_DAC_OVERRIDE))
 218                        return 0;
 219
 220        /*
 221         * Searching includes executable on directories, else just read.
 222         */
 223        if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
 224                if (capable(CAP_DAC_READ_SEARCH))
 225                        return 0;
 226
 227        return -EACCES;
 228}
 229
 230int inode_permission(struct inode *inode, int mask)
 231{
 232        int retval;
 233
 234        if (mask & MAY_WRITE) {
 235                umode_t mode = inode->i_mode;
 236
 237                /*
 238                 * Nobody gets write access to a read-only fs.
 239                 */
 240                if (IS_RDONLY(inode) &&
 241                    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
 242                        return -EROFS;
 243
 244                /*
 245                 * Nobody gets write access to an immutable file.
 246                 */
 247                if (IS_IMMUTABLE(inode))
 248                        return -EACCES;
 249        }
 250
 251        /* Ordinary permission routines do not understand MAY_APPEND. */
 252        if (inode->i_op && inode->i_op->permission) {
 253                retval = inode->i_op->permission(inode, mask);
 254                if (!retval) {
 255                        /*
 256                         * Exec permission on a regular file is denied if none
 257                         * of the execute bits are set.
 258                         *
 259                         * This check should be done by the ->permission()
 260                         * method.
 261                         */
 262                        if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) &&
 263                            !(inode->i_mode & S_IXUGO))
 264                                return -EACCES;
 265                }
 266        } else {
 267                retval = generic_permission(inode, mask, NULL);
 268        }
 269        if (retval)
 270                return retval;
 271
 272        retval = devcgroup_inode_permission(inode, mask);
 273        if (retval)
 274                return retval;
 275
 276        return security_inode_permission(inode,
 277                        mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND));
 278}
 279
 280/**
 281 * vfs_permission  -  check for access rights to a given path
 282 * @nd:         lookup result that describes the path
 283 * @mask:       right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 284 *
 285 * Used to check for read/write/execute permissions on a path.
 286 * We use "fsuid" for this, letting us set arbitrary permissions
 287 * for filesystem access without changing the "normal" uids which
 288 * are used for other things.
 289 */
 290int vfs_permission(struct nameidata *nd, int mask)
 291{
 292        return inode_permission(nd->path.dentry->d_inode, mask);
 293}
 294
 295/**
 296 * file_permission  -  check for additional access rights to a given file
 297 * @file:       file to check access rights for
 298 * @mask:       right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 299 *
 300 * Used to check for read/write/execute permissions on an already opened
 301 * file.
 302 *
 303 * Note:
 304 *      Do not use this function in new code.  All access checks should
 305 *      be done using vfs_permission().
 306 */
 307int file_permission(struct file *file, int mask)
 308{
 309        return inode_permission(file->f_path.dentry->d_inode, mask);
 310}
 311
 312/*
 313 * get_write_access() gets write permission for a file.
 314 * put_write_access() releases this write permission.
 315 * This is used for regular files.
 316 * We cannot support write (and maybe mmap read-write shared) accesses and
 317 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
 318 * can have the following values:
 319 * 0: no writers, no VM_DENYWRITE mappings
 320 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
 321 * > 0: (i_writecount) users are writing to the file.
 322 *
 323 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
 324 * except for the cases where we don't hold i_writecount yet. Then we need to
 325 * use {get,deny}_write_access() - these functions check the sign and refuse
 326 * to do the change if sign is wrong. Exclusion between them is provided by
 327 * the inode->i_lock spinlock.
 328 */
 329
 330int get_write_access(struct inode * inode)
 331{
 332        spin_lock(&inode->i_lock);
 333        if (atomic_read(&inode->i_writecount) < 0) {
 334                spin_unlock(&inode->i_lock);
 335                return -ETXTBSY;
 336        }
 337        atomic_inc(&inode->i_writecount);
 338        spin_unlock(&inode->i_lock);
 339
 340        return 0;
 341}
 342
 343int deny_write_access(struct file * file)
 344{
 345        struct inode *inode = file->f_path.dentry->d_inode;
 346
 347        spin_lock(&inode->i_lock);
 348        if (atomic_read(&inode->i_writecount) > 0) {
 349                spin_unlock(&inode->i_lock);
 350                return -ETXTBSY;
 351        }
 352        atomic_dec(&inode->i_writecount);
 353        spin_unlock(&inode->i_lock);
 354
 355        return 0;
 356}
 357
 358/**
 359 * path_get - get a reference to a path
 360 * @path: path to get the reference to
 361 *
 362 * Given a path increment the reference count to the dentry and the vfsmount.
 363 */
 364void path_get(struct path *path)
 365{
 366        mntget(path->mnt);
 367        dget(path->dentry);
 368}
 369EXPORT_SYMBOL(path_get);
 370
 371/**
 372 * path_put - put a reference to a path
 373 * @path: path to put the reference to
 374 *
 375 * Given a path decrement the reference count to the dentry and the vfsmount.
 376 */
 377void path_put(struct path *path)
 378{
 379        dput(path->dentry);
 380        mntput(path->mnt);
 381}
 382EXPORT_SYMBOL(path_put);
 383
 384/**
 385 * release_open_intent - free up open intent resources
 386 * @nd: pointer to nameidata
 387 */
 388void release_open_intent(struct nameidata *nd)
 389{
 390        if (nd->intent.open.file->f_path.dentry == NULL)
 391                put_filp(nd->intent.open.file);
 392        else
 393                fput(nd->intent.open.file);
 394}
 395
 396static inline struct dentry *
 397do_revalidate(struct dentry *dentry, struct nameidata *nd)
 398{
 399        int status = dentry->d_op->d_revalidate(dentry, nd);
 400        if (unlikely(status <= 0)) {
 401                /*
 402                 * The dentry failed validation.
 403                 * If d_revalidate returned 0 attempt to invalidate
 404                 * the dentry otherwise d_revalidate is asking us
 405                 * to return a fail status.
 406                 */
 407                if (!status) {
 408                        if (!d_invalidate(dentry)) {
 409                                dput(dentry);
 410                                dentry = NULL;
 411                        }
 412                } else {
 413                        dput(dentry);
 414                        dentry = ERR_PTR(status);
 415                }
 416        }
 417        return dentry;
 418}
 419
 420/*
 421 * Internal lookup() using the new generic dcache.
 422 * SMP-safe
 423 */
 424static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
 425{
 426        struct dentry * dentry = __d_lookup(parent, name);
 427
 428        /* lockess __d_lookup may fail due to concurrent d_move() 
 429         * in some unrelated directory, so try with d_lookup
 430         */
 431        if (!dentry)
 432                dentry = d_lookup(parent, name);
 433
 434        if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
 435                dentry = do_revalidate(dentry, nd);
 436
 437        return dentry;
 438}
 439
 440/*
 441 * Short-cut version of permission(), for calling by
 442 * path_walk(), when dcache lock is held.  Combines parts
 443 * of permission() and generic_permission(), and tests ONLY for
 444 * MAY_EXEC permission.
 445 *
 446 * If appropriate, check DAC only.  If not appropriate, or
 447 * short-cut DAC fails, then call permission() to do more
 448 * complete permission check.
 449 */
 450static int exec_permission_lite(struct inode *inode)
 451{
 452        umode_t mode = inode->i_mode;
 453
 454        if (inode->i_op && inode->i_op->permission)
 455                return -EAGAIN;
 456
 457        if (current->fsuid == inode->i_uid)
 458                mode >>= 6;
 459        else if (in_group_p(inode->i_gid))
 460                mode >>= 3;
 461
 462        if (mode & MAY_EXEC)
 463                goto ok;
 464
 465        if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
 466                goto ok;
 467
 468        if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
 469                goto ok;
 470
 471        if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
 472                goto ok;
 473
 474        return -EACCES;
 475ok:
 476        return security_inode_permission(inode, MAY_EXEC);
 477}
 478
 479/*
 480 * This is called when everything else fails, and we actually have
 481 * to go to the low-level filesystem to find out what we should do..
 482 *
 483 * We get the directory semaphore, and after getting that we also
 484 * make sure that nobody added the entry to the dcache in the meantime..
 485 * SMP-safe
 486 */
 487static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
 488{
 489        struct dentry * result;
 490        struct inode *dir = parent->d_inode;
 491
 492        mutex_lock(&dir->i_mutex);
 493        /*
 494         * First re-do the cached lookup just in case it was created
 495         * while we waited for the directory semaphore..
 496         *
 497         * FIXME! This could use version numbering or similar to
 498         * avoid unnecessary cache lookups.
 499         *
 500         * The "dcache_lock" is purely to protect the RCU list walker
 501         * from concurrent renames at this point (we mustn't get false
 502         * negatives from the RCU list walk here, unlike the optimistic
 503         * fast walk).
 504         *
 505         * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
 506         */
 507        result = d_lookup(parent, name);
 508        if (!result) {
 509                struct dentry *dentry;
 510
 511                /* Don't create child dentry for a dead directory. */
 512                result = ERR_PTR(-ENOENT);
 513                if (IS_DEADDIR(dir))
 514                        goto out_unlock;
 515
 516                dentry = d_alloc(parent, name);
 517                result = ERR_PTR(-ENOMEM);
 518                if (dentry) {
 519                        result = dir->i_op->lookup(dir, dentry, nd);
 520                        if (result)
 521                                dput(dentry);
 522                        else
 523                                result = dentry;
 524                }
 525out_unlock:
 526                mutex_unlock(&dir->i_mutex);
 527                return result;
 528        }
 529
 530        /*
 531         * Uhhuh! Nasty case: the cache was re-populated while
 532         * we waited on the semaphore. Need to revalidate.
 533         */
 534        mutex_unlock(&dir->i_mutex);
 535        if (result->d_op && result->d_op->d_revalidate) {
 536                result = do_revalidate(result, nd);
 537                if (!result)
 538                        result = ERR_PTR(-ENOENT);
 539        }
 540        return result;
 541}
 542
 543/* SMP-safe */
 544static __always_inline void
 545walk_init_root(const char *name, struct nameidata *nd)
 546{
 547        struct fs_struct *fs = current->fs;
 548
 549        read_lock(&fs->lock);
 550        nd->path = fs->root;
 551        path_get(&fs->root);
 552        read_unlock(&fs->lock);
 553}
 554
 555/*
 556 * Wrapper to retry pathname resolution whenever the underlying
 557 * file system returns an ESTALE.
 558 *
 559 * Retry the whole path once, forcing real lookup requests
 560 * instead of relying on the dcache.
 561 */
 562static __always_inline int link_path_walk(const char *name, struct nameidata *nd)
 563{
 564        struct path save = nd->path;
 565        int result;
 566
 567        /* make sure the stuff we saved doesn't go away */
 568        path_get(&save);
 569
 570        result = __link_path_walk(name, nd);
 571        if (result == -ESTALE) {
 572                /* nd->path had been dropped */
 573                nd->path = save;
 574                path_get(&nd->path);
 575                nd->flags |= LOOKUP_REVAL;
 576                result = __link_path_walk(name, nd);
 577        }
 578
 579        path_put(&save);
 580
 581        return result;
 582}
 583
 584static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
 585{
 586        int res = 0;
 587        char *name;
 588        if (IS_ERR(link))
 589                goto fail;
 590
 591        if (*link == '/') {
 592                path_put(&nd->path);
 593                walk_init_root(link, nd);
 594        }
 595        res = link_path_walk(link, nd);
 596        if (nd->depth || res || nd->last_type!=LAST_NORM)
 597                return res;
 598        /*
 599         * If it is an iterative symlinks resolution in open_namei() we
 600         * have to copy the last component. And all that crap because of
 601         * bloody create() on broken symlinks. Furrfu...
 602         */
 603        name = __getname();
 604        if (unlikely(!name)) {
 605                path_put(&nd->path);
 606                return -ENOMEM;
 607        }
 608        strcpy(name, nd->last.name);
 609        nd->last.name = name;
 610        return 0;
 611fail:
 612        path_put(&nd->path);
 613        return PTR_ERR(link);
 614}
 615
 616static void path_put_conditional(struct path *path, struct nameidata *nd)
 617{
 618        dput(path->dentry);
 619        if (path->mnt != nd->path.mnt)
 620                mntput(path->mnt);
 621}
 622
 623static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
 624{
 625        dput(nd->path.dentry);
 626        if (nd->path.mnt != path->mnt)
 627                mntput(nd->path.mnt);
 628        nd->path.mnt = path->mnt;
 629        nd->path.dentry = path->dentry;
 630}
 631
 632static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
 633{
 634        int error;
 635        void *cookie;
 636        struct dentry *dentry = path->dentry;
 637
 638        touch_atime(path->mnt, dentry);
 639        nd_set_link(nd, NULL);
 640
 641        if (path->mnt != nd->path.mnt) {
 642                path_to_nameidata(path, nd);
 643                dget(dentry);
 644        }
 645        mntget(path->mnt);
 646        cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
 647        error = PTR_ERR(cookie);
 648        if (!IS_ERR(cookie)) {
 649                char *s = nd_get_link(nd);
 650                error = 0;
 651                if (s)
 652                        error = __vfs_follow_link(nd, s);
 653                if (dentry->d_inode->i_op->put_link)
 654                        dentry->d_inode->i_op->put_link(dentry, nd, cookie);
 655        }
 656        path_put(path);
 657
 658        return error;
 659}
 660
 661/*
 662 * This limits recursive symlink follows to 8, while
 663 * limiting consecutive symlinks to 40.
 664 *
 665 * Without that kind of total limit, nasty chains of consecutive
 666 * symlinks can cause almost arbitrarily long lookups. 
 667 */
 668static inline int do_follow_link(struct path *path, struct nameidata *nd)
 669{
 670        int err = -ELOOP;
 671        if (current->link_count >= MAX_NESTED_LINKS)
 672                goto loop;
 673        if (current->total_link_count >= 40)
 674                goto loop;
 675        BUG_ON(nd->depth >= MAX_NESTED_LINKS);
 676        cond_resched();
 677        err = security_inode_follow_link(path->dentry, nd);
 678        if (err)
 679                goto loop;
 680        current->link_count++;
 681        current->total_link_count++;
 682        nd->depth++;
 683        err = __do_follow_link(path, nd);
 684        current->link_count--;
 685        nd->depth--;
 686        return err;
 687loop:
 688        path_put_conditional(path, nd);
 689        path_put(&nd->path);
 690        return err;
 691}
 692
 693int follow_up(struct vfsmount **mnt, struct dentry **dentry)
 694{
 695        struct vfsmount *parent;
 696        struct dentry *mountpoint;
 697        spin_lock(&vfsmount_lock);
 698        parent=(*mnt)->mnt_parent;
 699        if (parent == *mnt) {
 700                spin_unlock(&vfsmount_lock);
 701                return 0;
 702        }
 703        mntget(parent);
 704        mountpoint=dget((*mnt)->mnt_mountpoint);
 705        spin_unlock(&vfsmount_lock);
 706        dput(*dentry);
 707        *dentry = mountpoint;
 708        mntput(*mnt);
 709        *mnt = parent;
 710        return 1;
 711}
 712
 713/* no need for dcache_lock, as serialization is taken care in
 714 * namespace.c
 715 */
 716static int __follow_mount(struct path *path)
 717{
 718        int res = 0;
 719        while (d_mountpoint(path->dentry)) {
 720                struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
 721                if (!mounted)
 722                        break;
 723                dput(path->dentry);
 724                if (res)
 725                        mntput(path->mnt);
 726                path->mnt = mounted;
 727                path->dentry = dget(mounted->mnt_root);
 728                res = 1;
 729        }
 730        return res;
 731}
 732
 733static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
 734{
 735        while (d_mountpoint(*dentry)) {
 736                struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
 737                if (!mounted)
 738                        break;
 739                dput(*dentry);
 740                mntput(*mnt);
 741                *mnt = mounted;
 742                *dentry = dget(mounted->mnt_root);
 743        }
 744}
 745
 746/* no need for dcache_lock, as serialization is taken care in
 747 * namespace.c
 748 */
 749int follow_down(struct vfsmount **mnt, struct dentry **dentry)
 750{
 751        struct vfsmount *mounted;
 752
 753        mounted = lookup_mnt(*mnt, *dentry);
 754        if (mounted) {
 755                dput(*dentry);
 756                mntput(*mnt);
 757                *mnt = mounted;
 758                *dentry = dget(mounted->mnt_root);
 759                return 1;
 760        }
 761        return 0;
 762}
 763
 764static __always_inline void follow_dotdot(struct nameidata *nd)
 765{
 766        struct fs_struct *fs = current->fs;
 767
 768        while(1) {
 769                struct vfsmount *parent;
 770                struct dentry *old = nd->path.dentry;
 771
 772                read_lock(&fs->lock);
 773                if (nd->path.dentry == fs->root.dentry &&
 774                    nd->path.mnt == fs->root.mnt) {
 775                        read_unlock(&fs->lock);
 776                        break;
 777                }
 778                read_unlock(&fs->lock);
 779                spin_lock(&dcache_lock);
 780                if (nd->path.dentry != nd->path.mnt->mnt_root) {
 781                        nd->path.dentry = dget(nd->path.dentry->d_parent);
 782                        spin_unlock(&dcache_lock);
 783                        dput(old);
 784                        break;
 785                }
 786                spin_unlock(&dcache_lock);
 787                spin_lock(&vfsmount_lock);
 788                parent = nd->path.mnt->mnt_parent;
 789                if (parent == nd->path.mnt) {
 790                        spin_unlock(&vfsmount_lock);
 791                        break;
 792                }
 793                mntget(parent);
 794                nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint);
 795                spin_unlock(&vfsmount_lock);
 796                dput(old);
 797                mntput(nd->path.mnt);
 798                nd->path.mnt = parent;
 799        }
 800        follow_mount(&nd->path.mnt, &nd->path.dentry);
 801}
 802
 803/*
 804 *  It's more convoluted than I'd like it to be, but... it's still fairly
 805 *  small and for now I'd prefer to have fast path as straight as possible.
 806 *  It _is_ time-critical.
 807 */
 808static int do_lookup(struct nameidata *nd, struct qstr *name,
 809                     struct path *path)
 810{
 811        struct vfsmount *mnt = nd->path.mnt;
 812        struct dentry *dentry = __d_lookup(nd->path.dentry, name);
 813
 814        if (!dentry)
 815                goto need_lookup;
 816        if (dentry->d_op && dentry->d_op->d_revalidate)
 817                goto need_revalidate;
 818done:
 819        path->mnt = mnt;
 820        path->dentry = dentry;
 821        __follow_mount(path);
 822        return 0;
 823
 824need_lookup:
 825        dentry = real_lookup(nd->path.dentry, name, nd);
 826        if (IS_ERR(dentry))
 827                goto fail;
 828        goto done;
 829
 830need_revalidate:
 831        dentry = do_revalidate(dentry, nd);
 832        if (!dentry)
 833                goto need_lookup;
 834        if (IS_ERR(dentry))
 835                goto fail;
 836        goto done;
 837
 838fail:
 839        return PTR_ERR(dentry);
 840}
 841
 842/*
 843 * Name resolution.
 844 * This is the basic name resolution function, turning a pathname into
 845 * the final dentry. We expect 'base' to be positive and a directory.
 846 *
 847 * Returns 0 and nd will have valid dentry and mnt on success.
 848 * Returns error and drops reference to input namei data on failure.
 849 */
 850static int __link_path_walk(const char *name, struct nameidata *nd)
 851{
 852        struct path next;
 853        struct inode *inode;
 854        int err;
 855        unsigned int lookup_flags = nd->flags;
 856        
 857        while (*name=='/')
 858                name++;
 859        if (!*name)
 860                goto return_reval;
 861
 862        inode = nd->path.dentry->d_inode;
 863        if (nd->depth)
 864                lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
 865
 866        /* At this point we know we have a real path component. */
 867        for(;;) {
 868                unsigned long hash;
 869                struct qstr this;
 870                unsigned int c;
 871
 872                nd->flags |= LOOKUP_CONTINUE;
 873                err = exec_permission_lite(inode);
 874                if (err == -EAGAIN)
 875                        err = vfs_permission(nd, MAY_EXEC);
 876                if (err)
 877                        break;
 878
 879                this.name = name;
 880                c = *(const unsigned char *)name;
 881
 882                hash = init_name_hash();
 883                do {
 884                        name++;
 885                        hash = partial_name_hash(c, hash);
 886                        c = *(const unsigned char *)name;
 887                } while (c && (c != '/'));
 888                this.len = name - (const char *) this.name;
 889                this.hash = end_name_hash(hash);
 890
 891                /* remove trailing slashes? */
 892                if (!c)
 893                        goto last_component;
 894                while (*++name == '/');
 895                if (!*name)
 896                        goto last_with_slashes;
 897
 898                /*
 899                 * "." and ".." are special - ".." especially so because it has
 900                 * to be able to know about the current root directory and
 901                 * parent relationships.
 902                 */
 903                if (this.name[0] == '.') switch (this.len) {
 904                        default:
 905                                break;
 906                        case 2: 
 907                                if (this.name[1] != '.')
 908                                        break;
 909                                follow_dotdot(nd);
 910                                inode = nd->path.dentry->d_inode;
 911                                /* fallthrough */
 912                        case 1:
 913                                continue;
 914                }
 915                /*
 916                 * See if the low-level filesystem might want
 917                 * to use its own hash..
 918                 */
 919                if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
 920                        err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
 921                                                            &this);
 922                        if (err < 0)
 923                                break;
 924                }
 925                /* This does the actual lookups.. */
 926                err = do_lookup(nd, &this, &next);
 927                if (err)
 928                        break;
 929
 930                err = -ENOENT;
 931                inode = next.dentry->d_inode;
 932                if (!inode)
 933                        goto out_dput;
 934                err = -ENOTDIR; 
 935                if (!inode->i_op)
 936                        goto out_dput;
 937
 938                if (inode->i_op->follow_link) {
 939                        err = do_follow_link(&next, nd);
 940                        if (err)
 941                                goto return_err;
 942                        err = -ENOENT;
 943                        inode = nd->path.dentry->d_inode;
 944                        if (!inode)
 945                                break;
 946                        err = -ENOTDIR; 
 947                        if (!inode->i_op)
 948                                break;
 949                } else
 950                        path_to_nameidata(&next, nd);
 951                err = -ENOTDIR; 
 952                if (!inode->i_op->lookup)
 953                        break;
 954                continue;
 955                /* here ends the main loop */
 956
 957last_with_slashes:
 958                lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 959last_component:
 960                /* Clear LOOKUP_CONTINUE iff it was previously unset */
 961                nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
 962                if (lookup_flags & LOOKUP_PARENT)
 963                        goto lookup_parent;
 964                if (this.name[0] == '.') switch (this.len) {
 965                        default:
 966                                break;
 967                        case 2: 
 968                                if (this.name[1] != '.')
 969                                        break;
 970                                follow_dotdot(nd);
 971                                inode = nd->path.dentry->d_inode;
 972                                /* fallthrough */
 973                        case 1:
 974                                goto return_reval;
 975                }
 976                if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
 977                        err = nd->path.dentry->d_op->d_hash(nd->path.dentry,
 978                                                            &this);
 979                        if (err < 0)
 980                                break;
 981                }
 982                err = do_lookup(nd, &this, &next);
 983                if (err)
 984                        break;
 985                inode = next.dentry->d_inode;
 986                if ((lookup_flags & LOOKUP_FOLLOW)
 987                    && inode && inode->i_op && inode->i_op->follow_link) {
 988                        err = do_follow_link(&next, nd);
 989                        if (err)
 990                                goto return_err;
 991                        inode = nd->path.dentry->d_inode;
 992                } else
 993                        path_to_nameidata(&next, nd);
 994                err = -ENOENT;
 995                if (!inode)
 996                        break;
 997                if (lookup_flags & LOOKUP_DIRECTORY) {
 998                        err = -ENOTDIR; 
 999                        if (!inode->i_op || !inode->i_op->lookup)
1000                                break;
1001                }
1002                goto return_base;
1003lookup_parent:
1004                nd->last = this;
1005                nd->last_type = LAST_NORM;
1006                if (this.name[0] != '.')
1007                        goto return_base;
1008                if (this.len == 1)
1009                        nd->last_type = LAST_DOT;
1010                else if (this.len == 2 && this.name[1] == '.')
1011                        nd->last_type = LAST_DOTDOT;
1012                else
1013                        goto return_base;
1014return_reval:
1015                /*
1016                 * We bypassed the ordinary revalidation routines.
1017                 * We may need to check the cached dentry for staleness.
1018                 */
1019                if (nd->path.dentry && nd->path.dentry->d_sb &&
1020                    (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
1021                        err = -ESTALE;
1022                        /* Note: we do not d_invalidate() */
1023                        if (!nd->path.dentry->d_op->d_revalidate(
1024                                        nd->path.dentry, nd))
1025                                break;
1026                }
1027return_base:
1028                return 0;
1029out_dput:
1030                path_put_conditional(&next, nd);
1031                break;
1032        }
1033        path_put(&nd->path);
1034return_err:
1035        return err;
1036}
1037
1038static int path_walk(const char *name, struct nameidata *nd)
1039{
1040        current->total_link_count = 0;
1041        return link_path_walk(name, nd);
1042}
1043
1044/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1045static int do_path_lookup(int dfd, const char *name,
1046                                unsigned int flags, struct nameidata *nd)
1047{
1048        int retval = 0;
1049        int fput_needed;
1050        struct file *file;
1051        struct fs_struct *fs = current->fs;
1052
1053        nd->last_type = LAST_ROOT; /* if there are only slashes... */
1054        nd->flags = flags;
1055        nd->depth = 0;
1056
1057        if (*name=='/') {
1058                read_lock(&fs->lock);
1059                nd->path = fs->root;
1060                path_get(&fs->root);
1061                read_unlock(&fs->lock);
1062        } else if (dfd == AT_FDCWD) {
1063                read_lock(&fs->lock);
1064                nd->path = fs->pwd;
1065                path_get(&fs->pwd);
1066                read_unlock(&fs->lock);
1067        } else {
1068                struct dentry *dentry;
1069
1070                file = fget_light(dfd, &fput_needed);
1071                retval = -EBADF;
1072                if (!file)
1073                        goto out_fail;
1074
1075                dentry = file->f_path.dentry;
1076
1077                retval = -ENOTDIR;
1078                if (!S_ISDIR(dentry->d_inode->i_mode))
1079                        goto fput_fail;
1080
1081                retval = file_permission(file, MAY_EXEC);
1082                if (retval)
1083                        goto fput_fail;
1084
1085                nd->path = file->f_path;
1086                path_get(&file->f_path);
1087
1088                fput_light(file, fput_needed);
1089        }
1090
1091        retval = path_walk(name, nd);
1092        if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
1093                                nd->path.dentry->d_inode))
1094                audit_inode(name, nd->path.dentry);
1095out_fail:
1096        return retval;
1097
1098fput_fail:
1099        fput_light(file, fput_needed);
1100        goto out_fail;
1101}
1102
1103int path_lookup(const char *name, unsigned int flags,
1104                        struct nameidata *nd)
1105{
1106        return do_path_lookup(AT_FDCWD, name, flags, nd);
1107}
1108
1109/**
1110 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1111 * @dentry:  pointer to dentry of the base directory
1112 * @mnt: pointer to vfs mount of the base directory
1113 * @name: pointer to file name
1114 * @flags: lookup flags
1115 * @nd: pointer to nameidata
1116 */
1117int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1118                    const char *name, unsigned int flags,
1119                    struct nameidata *nd)
1120{
1121        int retval;
1122
1123        /* same as do_path_lookup */
1124        nd->last_type = LAST_ROOT;
1125        nd->flags = flags;
1126        nd->depth = 0;
1127
1128        nd->path.dentry = dentry;
1129        nd->path.mnt = mnt;
1130        path_get(&nd->path);
1131
1132        retval = path_walk(name, nd);
1133        if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
1134                                nd->path.dentry->d_inode))
1135                audit_inode(name, nd->path.dentry);
1136
1137        return retval;
1138
1139}
1140
1141static int __path_lookup_intent_open(int dfd, const char *name,
1142                unsigned int lookup_flags, struct nameidata *nd,
1143                int open_flags, int create_mode)
1144{
1145        struct file *filp = get_empty_filp();
1146        int err;
1147
1148        if (filp == NULL)
1149                return -ENFILE;
1150        nd->intent.open.file = filp;
1151        nd->intent.open.flags = open_flags;
1152        nd->intent.open.create_mode = create_mode;
1153        err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd);
1154        if (IS_ERR(nd->intent.open.file)) {
1155                if (err == 0) {
1156                        err = PTR_ERR(nd->intent.open.file);
1157                        path_put(&nd->path);
1158                }
1159        } else if (err != 0)
1160                release_open_intent(nd);
1161        return err;
1162}
1163
1164/**
1165 * path_lookup_open - lookup a file path with open intent
1166 * @dfd: the directory to use as base, or AT_FDCWD
1167 * @name: pointer to file name
1168 * @lookup_flags: lookup intent flags
1169 * @nd: pointer to nameidata
1170 * @open_flags: open intent flags
1171 */
1172int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags,
1173                struct nameidata *nd, int open_flags)
1174{
1175        return __path_lookup_intent_open(dfd, name, lookup_flags, nd,
1176                        open_flags, 0);
1177}
1178
1179/**
1180 * path_lookup_create - lookup a file path with open + create intent
1181 * @dfd: the directory to use as base, or AT_FDCWD
1182 * @name: pointer to file name
1183 * @lookup_flags: lookup intent flags
1184 * @nd: pointer to nameidata
1185 * @open_flags: open intent flags
1186 * @create_mode: create intent flags
1187 */
1188static int path_lookup_create(int dfd, const char *name,
1189                              unsigned int lookup_flags, struct nameidata *nd,
1190                              int open_flags, int create_mode)
1191{
1192        return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE,
1193                        nd, open_flags, create_mode);
1194}
1195
1196static struct dentry *__lookup_hash(struct qstr *name,
1197                struct dentry *base, struct nameidata *nd)
1198{
1199        struct dentry *dentry;
1200        struct inode *inode;
1201        int err;
1202
1203        inode = base->d_inode;
1204
1205        /*
1206         * See if the low-level filesystem might want
1207         * to use its own hash..
1208         */
1209        if (base->d_op && base->d_op->d_hash) {
1210                err = base->d_op->d_hash(base, name);
1211                dentry = ERR_PTR(err);
1212                if (err < 0)
1213                        goto out;
1214        }
1215
1216        dentry = cached_lookup(base, name, nd);
1217        if (!dentry) {
1218                struct dentry *new;
1219
1220                /* Don't create child dentry for a dead directory. */
1221                dentry = ERR_PTR(-ENOENT);
1222                if (IS_DEADDIR(inode))
1223                        goto out;
1224
1225                new = d_alloc(base, name);
1226                dentry = ERR_PTR(-ENOMEM);
1227                if (!new)
1228                        goto out;
1229                dentry = inode->i_op->lookup(inode, new, nd);
1230                if (!dentry)
1231                        dentry = new;
1232                else
1233                        dput(new);
1234        }
1235out:
1236        return dentry;
1237}
1238
1239/*
1240 * Restricted form of lookup. Doesn't follow links, single-component only,
1241 * needs parent already locked. Doesn't follow mounts.
1242 * SMP-safe.
1243 */
1244static struct dentry *lookup_hash(struct nameidata *nd)
1245{
1246        int err;
1247
1248        err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC);
1249        if (err)
1250                return ERR_PTR(err);
1251        return __lookup_hash(&nd->last, nd->path.dentry, nd);
1252}
1253
1254static int __lookup_one_len(const char *name, struct qstr *this,
1255                struct dentry *base, int len)
1256{
1257        unsigned long hash;
1258        unsigned int c;
1259
1260        this->name = name;
1261        this->len = len;
1262        if (!len)
1263                return -EACCES;
1264
1265        hash = init_name_hash();
1266        while (len--) {
1267                c = *(const unsigned char *)name++;
1268                if (c == '/' || c == '\0')
1269                        return -EACCES;
1270                hash = partial_name_hash(c, hash);
1271        }
1272        this->hash = end_name_hash(hash);
1273        return 0;
1274}
1275
1276/**
1277 * lookup_one_len - filesystem helper to lookup single pathname component
1278 * @name:       pathname component to lookup
1279 * @base:       base directory to lookup from
1280 * @len:        maximum length @len should be interpreted to
1281 *
1282 * Note that this routine is purely a helper for filesystem usage and should
1283 * not be called by generic code.  Also note that by using this function the
1284 * nameidata argument is passed to the filesystem methods and a filesystem
1285 * using this helper needs to be prepared for that.
1286 */
1287struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1288{
1289        int err;
1290        struct qstr this;
1291
1292        err = __lookup_one_len(name, &this, base, len);
1293        if (err)
1294                return ERR_PTR(err);
1295
1296        err = inode_permission(base->d_inode, MAY_EXEC);
1297        if (err)
1298                return ERR_PTR(err);
1299        return __lookup_hash(&this, base, NULL);
1300}
1301
1302/**
1303 * lookup_one_noperm - bad hack for sysfs
1304 * @name:       pathname component to lookup
1305 * @base:       base directory to lookup from
1306 *
1307 * This is a variant of lookup_one_len that doesn't perform any permission
1308 * checks.   It's a horrible hack to work around the braindead sysfs
1309 * architecture and should not be used anywhere else.
1310 *
1311 * DON'T USE THIS FUNCTION EVER, thanks.
1312 */
1313struct dentry *lookup_one_noperm(const char *name, struct dentry *base)
1314{
1315        int err;
1316        struct qstr this;
1317
1318        err = __lookup_one_len(name, &this, base, strlen(name));
1319        if (err)
1320                return ERR_PTR(err);
1321        return __lookup_hash(&this, base, NULL);
1322}
1323
1324int user_path_at(int dfd, const char __user *name, unsigned flags,
1325                 struct path *path)
1326{
1327        struct nameidata nd;
1328        char *tmp = getname(name);
1329        int err = PTR_ERR(tmp);
1330        if (!IS_ERR(tmp)) {
1331
1332                BUG_ON(flags & LOOKUP_PARENT);
1333
1334                err = do_path_lookup(dfd, tmp, flags, &nd);
1335                putname(tmp);
1336                if (!err)
1337                        *path = nd.path;
1338        }
1339        return err;
1340}
1341
1342static int user_path_parent(int dfd, const char __user *path,
1343                        struct nameidata *nd, char **name)
1344{
1345        char *s = getname(path);
1346        int error;
1347
1348        if (IS_ERR(s))
1349                return PTR_ERR(s);
1350
1351        error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1352        if (error)
1353                putname(s);
1354        else
1355                *name = s;
1356
1357        return error;
1358}
1359
1360/*
1361 * It's inline, so penalty for filesystems that don't use sticky bit is
1362 * minimal.
1363 */
1364static inline int check_sticky(struct inode *dir, struct inode *inode)
1365{
1366        if (!(dir->i_mode & S_ISVTX))
1367                return 0;
1368        if (inode->i_uid == current->fsuid)
1369                return 0;
1370        if (dir->i_uid == current->fsuid)
1371                return 0;
1372        return !capable(CAP_FOWNER);
1373}
1374
1375/*
1376 *      Check whether we can remove a link victim from directory dir, check
1377 *  whether the type of victim is right.
1378 *  1. We can't do it if dir is read-only (done in permission())
1379 *  2. We should have write and exec permissions on dir
1380 *  3. We can't remove anything from append-only dir
1381 *  4. We can't do anything with immutable dir (done in permission())
1382 *  5. If the sticky bit on dir is set we should either
1383 *      a. be owner of dir, or
1384 *      b. be owner of victim, or
1385 *      c. have CAP_FOWNER capability
1386 *  6. If the victim is append-only or immutable we can't do antyhing with
1387 *     links pointing to it.
1388 *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1389 *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1390 *  9. We can't remove a root or mountpoint.
1391 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1392 *     nfs_async_unlink().
1393 */
1394static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1395{
1396        int error;
1397
1398        if (!victim->d_inode)
1399                return -ENOENT;
1400
1401        BUG_ON(victim->d_parent->d_inode != dir);
1402        audit_inode_child(victim->d_name.name, victim, dir);
1403
1404        error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1405        if (error)
1406                return error;
1407        if (IS_APPEND(dir))
1408                return -EPERM;
1409        if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1410            IS_IMMUTABLE(victim->d_inode))
1411                return -EPERM;
1412        if (isdir) {
1413                if (!S_ISDIR(victim->d_inode->i_mode))
1414                        return -ENOTDIR;
1415                if (IS_ROOT(victim))
1416                        return -EBUSY;
1417        } else if (S_ISDIR(victim->d_inode->i_mode))
1418                return -EISDIR;
1419        if (IS_DEADDIR(dir))
1420                return -ENOENT;
1421        if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1422                return -EBUSY;
1423        return 0;
1424}
1425
1426/*      Check whether we can create an object with dentry child in directory
1427 *  dir.
1428 *  1. We can't do it if child already exists (open has special treatment for
1429 *     this case, but since we are inlined it's OK)
1430 *  2. We can't do it if dir is read-only (done in permission())
1431 *  3. We should have write and exec permissions on dir
1432 *  4. We can't do it if dir is immutable (done in permission())
1433 */
1434static inline int may_create(struct inode *dir, struct dentry *child)
1435{
1436        if (child->d_inode)
1437                return -EEXIST;
1438        if (IS_DEADDIR(dir))
1439                return -ENOENT;
1440        return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1441}
1442
1443/* 
1444 * O_DIRECTORY translates into forcing a directory lookup.
1445 */
1446static inline int lookup_flags(unsigned int f)
1447{
1448        unsigned long retval = LOOKUP_FOLLOW;
1449
1450        if (f & O_NOFOLLOW)
1451                retval &= ~LOOKUP_FOLLOW;
1452        
1453        if (f & O_DIRECTORY)
1454                retval |= LOOKUP_DIRECTORY;
1455
1456        return retval;
1457}
1458
1459/*
1460 * p1 and p2 should be directories on the same fs.
1461 */
1462struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1463{
1464        struct dentry *p;
1465
1466        if (p1 == p2) {
1467                mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1468                return NULL;
1469        }
1470
1471        mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1472
1473        for (p = p1; p->d_parent != p; p = p->d_parent) {
1474                if (p->d_parent == p2) {
1475                        mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1476                        mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1477                        return p;
1478                }
1479        }
1480
1481        for (p = p2; p->d_parent != p; p = p->d_parent) {
1482                if (p->d_parent == p1) {
1483                        mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1484                        mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1485                        return p;
1486                }
1487        }
1488
1489        mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1490        mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1491        return NULL;
1492}
1493
1494void unlock_rename(struct dentry *p1, struct dentry *p2)
1495{
1496        mutex_unlock(&p1->d_inode->i_mutex);
1497        if (p1 != p2) {
1498                mutex_unlock(&p2->d_inode->i_mutex);
1499                mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1500        }
1501}
1502
1503int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1504                struct nameidata *nd)
1505{
1506        int error = may_create(dir, dentry);
1507
1508        if (error)
1509                return error;
1510
1511        if (!dir->i_op || !dir->i_op->create)
1512                return -EACCES; /* shouldn't it be ENOSYS? */
1513        mode &= S_IALLUGO;
1514        mode |= S_IFREG;
1515        error = security_inode_create(dir, dentry, mode);
1516        if (error)
1517                return error;
1518        DQUOT_INIT(dir);
1519        error = dir->i_op->create(dir, dentry, mode, nd);
1520        if (!error)
1521                fsnotify_create(dir, dentry);
1522        return error;
1523}
1524
1525int may_open(struct nameidata *nd, int acc_mode, int flag)
1526{
1527        struct dentry *dentry = nd->path.dentry;
1528        struct inode *inode = dentry->d_inode;
1529        int error;
1530
1531        if (!inode)
1532                return -ENOENT;
1533
1534        if (S_ISLNK(inode->i_mode))
1535                return -ELOOP;
1536        
1537        if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE))
1538                return -EISDIR;
1539
1540        /*
1541         * FIFO's, sockets and device files are special: they don't
1542         * actually live on the filesystem itself, and as such you
1543         * can write to them even if the filesystem is read-only.
1544         */
1545        if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
1546                flag &= ~O_TRUNC;
1547        } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
1548                if (nd->path.mnt->mnt_flags & MNT_NODEV)
1549                        return -EACCES;
1550
1551                flag &= ~O_TRUNC;
1552        }
1553
1554        error = vfs_permission(nd, acc_mode);
1555        if (error)
1556                return error;
1557        /*
1558         * An append-only file must be opened in append mode for writing.
1559         */
1560        if (IS_APPEND(inode)) {
1561                if  ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1562                        return -EPERM;
1563                if (flag & O_TRUNC)
1564                        return -EPERM;
1565        }
1566
1567        /* O_NOATIME can only be set by the owner or superuser */
1568        if (flag & O_NOATIME)
1569                if (!is_owner_or_cap(inode))
1570                        return -EPERM;
1571
1572        /*
1573         * Ensure there are no outstanding leases on the file.
1574         */
1575        error = break_lease(inode, flag);
1576        if (error)
1577                return error;
1578
1579        if (flag & O_TRUNC) {
1580                error = get_write_access(inode);
1581                if (error)
1582                        return error;
1583
1584                /*
1585                 * Refuse to truncate files with mandatory locks held on them.
1586                 */
1587                error = locks_verify_locked(inode);
1588                if (!error) {
1589                        DQUOT_INIT(inode);
1590
1591                        error = do_truncate(dentry, 0,
1592                                            ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
1593                                            NULL);
1594                }
1595                put_write_access(inode);
1596                if (error)
1597                        return error;
1598        } else
1599                if (flag & FMODE_WRITE)
1600                        DQUOT_INIT(inode);
1601
1602        return 0;
1603}
1604
1605/*
1606 * Be careful about ever adding any more callers of this
1607 * function.  Its flags must be in the namei format, not
1608 * what get passed to sys_open().
1609 */
1610static int __open_namei_create(struct nameidata *nd, struct path *path,
1611                                int flag, int mode)
1612{
1613        int error;
1614        struct dentry *dir = nd->path.dentry;
1615
1616        if (!IS_POSIXACL(dir->d_inode))
1617                mode &= ~current->fs->umask;
1618        error = vfs_create(dir->d_inode, path->dentry, mode, nd);
1619        mutex_unlock(&dir->d_inode->i_mutex);
1620        dput(nd->path.dentry);
1621        nd->path.dentry = path->dentry;
1622        if (error)
1623                return error;
1624        /* Don't check for write permission, don't truncate */
1625        return may_open(nd, 0, flag & ~O_TRUNC);
1626}
1627
1628/*
1629 * Note that while the flag value (low two bits) for sys_open means:
1630 *      00 - read-only
1631 *      01 - write-only
1632 *      10 - read-write
1633 *      11 - special
1634 * it is changed into
1635 *      00 - no permissions needed
1636 *      01 - read-permission
1637 *      10 - write-permission
1638 *      11 - read-write
1639 * for the internal routines (ie open_namei()/follow_link() etc)
1640 * This is more logical, and also allows the 00 "no perm needed"
1641 * to be used for symlinks (where the permissions are checked
1642 * later).
1643 *
1644*/
1645static inline int open_to_namei_flags(int flag)
1646{
1647        if ((flag+1) & O_ACCMODE)
1648                flag++;
1649        return flag;
1650}
1651
1652static int open_will_write_to_fs(int flag, struct inode *inode)
1653{
1654        /*
1655         * We'll never write to the fs underlying
1656         * a device file.
1657         */
1658        if (special_file(inode->i_mode))
1659                return 0;
1660        return (flag & O_TRUNC);
1661}
1662
1663/*
1664 * Note that the low bits of the passed in "open_flag"
1665 * are not the same as in the local variable "flag". See
1666 * open_to_namei_flags() for more details.
1667 */
1668struct file *do_filp_open(int dfd, const char *pathname,
1669                int open_flag, int mode)
1670{
1671        struct file *filp;
1672        struct nameidata nd;
1673        int acc_mode, error;
1674        struct path path;
1675        struct dentry *dir;
1676        int count = 0;
1677        int will_write;
1678        int flag = open_to_namei_flags(open_flag);
1679
1680        acc_mode = MAY_OPEN | ACC_MODE(flag);
1681
1682        /* O_TRUNC implies we need access checks for write permissions */
1683        if (flag & O_TRUNC)
1684                acc_mode |= MAY_WRITE;
1685
1686        /* Allow the LSM permission hook to distinguish append 
1687           access from general write access. */
1688        if (flag & O_APPEND)
1689                acc_mode |= MAY_APPEND;
1690
1691        /*
1692         * The simplest case - just a plain lookup.
1693         */
1694        if (!(flag & O_CREAT)) {
1695                error = path_lookup_open(dfd, pathname, lookup_flags(flag),
1696                                         &nd, flag);
1697                if (error)
1698                        return ERR_PTR(error);
1699                goto ok;
1700        }
1701
1702        /*
1703         * Create - we need to know the parent.
1704         */
1705        error = path_lookup_create(dfd, pathname, LOOKUP_PARENT,
1706                                   &nd, flag, mode);
1707        if (error)
1708                return ERR_PTR(error);
1709
1710        /*
1711         * We have the parent and last component. First of all, check
1712         * that we are not asked to creat(2) an obvious directory - that
1713         * will not do.
1714         */
1715        error = -EISDIR;
1716        if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len])
1717                goto exit;
1718
1719        dir = nd.path.dentry;
1720        nd.flags &= ~LOOKUP_PARENT;
1721        mutex_lock(&dir->d_inode->i_mutex);
1722        path.dentry = lookup_hash(&nd);
1723        path.mnt = nd.path.mnt;
1724
1725do_last:
1726        error = PTR_ERR(path.dentry);
1727        if (IS_ERR(path.dentry)) {
1728                mutex_unlock(&dir->d_inode->i_mutex);
1729                goto exit;
1730        }
1731
1732        if (IS_ERR(nd.intent.open.file)) {
1733                error = PTR_ERR(nd.intent.open.file);
1734                goto exit_mutex_unlock;
1735        }
1736
1737        /* Negative dentry, just create the file */
1738        if (!path.dentry->d_inode) {
1739                /*
1740                 * This write is needed to ensure that a
1741                 * ro->rw transition does not occur between
1742                 * the time when the file is created and when
1743                 * a permanent write count is taken through
1744                 * the 'struct file' in nameidata_to_filp().
1745                 */
1746                error = mnt_want_write(nd.path.mnt);
1747                if (error)
1748                        goto exit_mutex_unlock;
1749                error = __open_namei_create(&nd, &path, flag, mode);
1750                if (error) {
1751                        mnt_drop_write(nd.path.mnt);
1752                        goto exit;
1753                }
1754                filp = nameidata_to_filp(&nd, open_flag);
1755                mnt_drop_write(nd.path.mnt);
1756                return filp;
1757        }
1758
1759        /*
1760         * It already exists.
1761         */
1762        mutex_unlock(&dir->d_inode->i_mutex);
1763        audit_inode(pathname, path.dentry);
1764
1765        error = -EEXIST;
1766        if (flag & O_EXCL)
1767                goto exit_dput;
1768
1769        if (__follow_mount(&path)) {
1770                error = -ELOOP;
1771                if (flag & O_NOFOLLOW)
1772                        goto exit_dput;
1773        }
1774
1775        error = -ENOENT;
1776        if (!path.dentry->d_inode)
1777                goto exit_dput;
1778        if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
1779                goto do_link;
1780
1781        path_to_nameidata(&path, &nd);
1782        error = -EISDIR;
1783        if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
1784                goto exit;
1785ok:
1786        /*
1787         * Consider:
1788         * 1. may_open() truncates a file
1789         * 2. a rw->ro mount transition occurs
1790         * 3. nameidata_to_filp() fails due to
1791         *    the ro mount.
1792         * That would be inconsistent, and should
1793         * be avoided. Taking this mnt write here
1794         * ensures that (2) can not occur.
1795         */
1796        will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode);
1797        if (will_write) {
1798                error = mnt_want_write(nd.path.mnt);
1799                if (error)
1800                        goto exit;
1801        }
1802        error = may_open(&nd, acc_mode, flag);
1803        if (error) {
1804                if (will_write)
1805                        mnt_drop_write(nd.path.mnt);
1806                goto exit;
1807        }
1808        filp = nameidata_to_filp(&nd, open_flag);
1809        /*
1810         * It is now safe to drop the mnt write
1811         * because the filp has had a write taken
1812         * on its behalf.
1813         */
1814        if (will_write)
1815                mnt_drop_write(nd.path.mnt);
1816        return filp;
1817
1818exit_mutex_unlock:
1819        mutex_unlock(&dir->d_inode->i_mutex);
1820exit_dput:
1821        path_put_conditional(&path, &nd);
1822exit:
1823        if (!IS_ERR(nd.intent.open.file))
1824                release_open_intent(&nd);
1825        path_put(&nd.path);
1826        return ERR_PTR(error);
1827
1828do_link:
1829        error = -ELOOP;
1830        if (flag & O_NOFOLLOW)
1831                goto exit_dput;
1832        /*
1833         * This is subtle. Instead of calling do_follow_link() we do the
1834         * thing by hands. The reason is that this way we have zero link_count
1835         * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1836         * After that we have the parent and last component, i.e.
1837         * we are in the same situation as after the first path_walk().
1838         * Well, almost - if the last component is normal we get its copy
1839         * stored in nd->last.name and we will have to putname() it when we
1840         * are done. Procfs-like symlinks just set LAST_BIND.
1841         */
1842        nd.flags |= LOOKUP_PARENT;
1843        error = security_inode_follow_link(path.dentry, &nd);
1844        if (error)
1845                goto exit_dput;
1846        error = __do_follow_link(&path, &nd);
1847        if (error) {
1848                /* Does someone understand code flow here? Or it is only
1849                 * me so stupid? Anathema to whoever designed this non-sense
1850                 * with "intent.open".
1851                 */
1852                release_open_intent(&nd);
1853                return ERR_PTR(error);
1854        }
1855        nd.flags &= ~LOOKUP_PARENT;
1856        if (nd.last_type == LAST_BIND)
1857                goto ok;
1858        error = -EISDIR;
1859        if (nd.last_type != LAST_NORM)
1860                goto exit;
1861        if (nd.last.name[nd.last.len]) {
1862                __putname(nd.last.name);
1863                goto exit;
1864        }
1865        error = -ELOOP;
1866        if (count++==32) {
1867                __putname(nd.last.name);
1868                goto exit;
1869        }
1870        dir = nd.path.dentry;
1871        mutex_lock(&dir->d_inode->i_mutex);
1872        path.dentry = lookup_hash(&nd);
1873        path.mnt = nd.path.mnt;
1874        __putname(nd.last.name);
1875        goto do_last;
1876}
1877
1878/**
1879 * filp_open - open file and return file pointer
1880 *
1881 * @filename:   path to open
1882 * @flags:      open flags as per the open(2) second argument
1883 * @mode:       mode for the new file if O_CREAT is set, else ignored
1884 *
1885 * This is the helper to open a file from kernelspace if you really
1886 * have to.  But in generally you should not do this, so please move
1887 * along, nothing to see here..
1888 */
1889struct file *filp_open(const char *filename, int flags, int mode)
1890{
1891        return do_filp_open(AT_FDCWD, filename, flags, mode);
1892}
1893EXPORT_SYMBOL(filp_open);
1894
1895/**
1896 * lookup_create - lookup a dentry, creating it if it doesn't exist
1897 * @nd: nameidata info
1898 * @is_dir: directory flag
1899 *
1900 * Simple function to lookup and return a dentry and create it
1901 * if it doesn't exist.  Is SMP-safe.
1902 *
1903 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1904 */
1905struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1906{
1907        struct dentry *dentry = ERR_PTR(-EEXIST);
1908
1909        mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
1910        /*
1911         * Yucky last component or no last component at all?
1912         * (foo/., foo/.., /////)
1913         */
1914        if (nd->last_type != LAST_NORM)
1915                goto fail;
1916        nd->flags &= ~LOOKUP_PARENT;
1917        nd->flags |= LOOKUP_CREATE;
1918        nd->intent.open.flags = O_EXCL;
1919
1920        /*
1921         * Do the final lookup.
1922         */
1923        dentry = lookup_hash(nd);
1924        if (IS_ERR(dentry))
1925                goto fail;
1926
1927        if (dentry->d_inode)
1928                goto eexist;
1929        /*
1930         * Special case - lookup gave negative, but... we had foo/bar/
1931         * From the vfs_mknod() POV we just have a negative dentry -
1932         * all is fine. Let's be bastards - you had / on the end, you've
1933         * been asking for (non-existent) directory. -ENOENT for you.
1934         */
1935        if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
1936                dput(dentry);
1937                dentry = ERR_PTR(-ENOENT);
1938        }
1939        return dentry;
1940eexist:
1941        dput(dentry);
1942        dentry = ERR_PTR(-EEXIST);
1943fail:
1944        return dentry;
1945}
1946EXPORT_SYMBOL_GPL(lookup_create);
1947
1948int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1949{
1950        int error = may_create(dir, dentry);
1951
1952        if (error)
1953                return error;
1954
1955        if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1956                return -EPERM;
1957
1958        if (!dir->i_op || !dir->i_op->mknod)
1959                return -EPERM;
1960
1961        error = devcgroup_inode_mknod(mode, dev);
1962        if (error)
1963                return error;
1964
1965        error = security_inode_mknod(dir, dentry, mode, dev);
1966        if (error)
1967                return error;
1968
1969        DQUOT_INIT(dir);
1970        error = dir->i_op->mknod(dir, dentry, mode, dev);
1971        if (!error)
1972                fsnotify_create(dir, dentry);
1973        return error;
1974}
1975
1976static int may_mknod(mode_t mode)
1977{
1978        switch (mode & S_IFMT) {
1979        case S_IFREG:
1980        case S_IFCHR:
1981        case S_IFBLK:
1982        case S_IFIFO:
1983        case S_IFSOCK:
1984        case 0: /* zero mode translates to S_IFREG */
1985                return 0;
1986        case S_IFDIR:
1987                return -EPERM;
1988        default:
1989                return -EINVAL;
1990        }
1991}
1992
1993asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
1994                                unsigned dev)
1995{
1996        int error;
1997        char *tmp;
1998        struct dentry *dentry;
1999        struct nameidata nd;
2000
2001        if (S_ISDIR(mode))
2002                return -EPERM;
2003
2004        error = user_path_parent(dfd, filename, &nd, &tmp);
2005        if (error)
2006                return error;
2007
2008        dentry = lookup_create(&nd, 0);
2009        if (IS_ERR(dentry)) {
2010                error = PTR_ERR(dentry);
2011                goto out_unlock;
2012        }
2013        if (!IS_POSIXACL(nd.path.dentry->d_inode))
2014                mode &= ~current->fs->umask;
2015        error = may_mknod(mode);
2016        if (error)
2017                goto out_dput;
2018        error = mnt_want_write(nd.path.mnt);
2019        if (error)
2020                goto out_dput;
2021        switch (mode & S_IFMT) {
2022                case 0: case S_IFREG:
2023                        error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
2024                        break;
2025                case S_IFCHR: case S_IFBLK:
2026                        error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
2027                                        new_decode_dev(dev));
2028                        break;
2029                case S_IFIFO: case S_IFSOCK:
2030                        error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
2031                        break;
2032        }
2033        mnt_drop_write(nd.path.mnt);
2034out_dput:
2035        dput(dentry);
2036out_unlock:
2037        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2038        path_put(&nd.path);
2039        putname(tmp);
2040
2041        return error;
2042}
2043
2044asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev)
2045{
2046        return sys_mknodat(AT_FDCWD, filename, mode, dev);
2047}
2048
2049int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2050{
2051        int error = may_create(dir, dentry);
2052
2053        if (error)
2054                return error;
2055
2056        if (!dir->i_op || !dir->i_op->mkdir)
2057                return -EPERM;
2058
2059        mode &= (S_IRWXUGO|S_ISVTX);
2060        error = security_inode_mkdir(dir, dentry, mode);
2061        if (error)
2062                return error;
2063
2064        DQUOT_INIT(dir);
2065        error = dir->i_op->mkdir(dir, dentry, mode);
2066        if (!error)
2067                fsnotify_mkdir(dir, dentry);
2068        return error;
2069}
2070
2071asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
2072{
2073        int error = 0;
2074        char * tmp;
2075        struct dentry *dentry;
2076        struct nameidata nd;
2077
2078        error = user_path_parent(dfd, pathname, &nd, &tmp);
2079        if (error)
2080                goto out_err;
2081
2082        dentry = lookup_create(&nd, 1);
2083        error = PTR_ERR(dentry);
2084        if (IS_ERR(dentry))
2085                goto out_unlock;
2086
2087        if (!IS_POSIXACL(nd.path.dentry->d_inode))
2088                mode &= ~current->fs->umask;
2089        error = mnt_want_write(nd.path.mnt);
2090        if (error)
2091                goto out_dput;
2092        error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
2093        mnt_drop_write(nd.path.mnt);
2094out_dput:
2095        dput(dentry);
2096out_unlock:
2097        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2098        path_put(&nd.path);
2099        putname(tmp);
2100out_err:
2101        return error;
2102}
2103
2104asmlinkage long sys_mkdir(const char __user *pathname, int mode)
2105{
2106        return sys_mkdirat(AT_FDCWD, pathname, mode);
2107}
2108
2109/*
2110 * We try to drop the dentry early: we should have
2111 * a usage count of 2 if we're the only user of this
2112 * dentry, and if that is true (possibly after pruning
2113 * the dcache), then we drop the dentry now.
2114 *
2115 * A low-level filesystem can, if it choses, legally
2116 * do a
2117 *
2118 *      if (!d_unhashed(dentry))
2119 *              return -EBUSY;
2120 *
2121 * if it cannot handle the case of removing a directory
2122 * that is still in use by something else..
2123 */
2124void dentry_unhash(struct dentry *dentry)
2125{
2126        dget(dentry);
2127        shrink_dcache_parent(dentry);
2128        spin_lock(&dcache_lock);
2129        spin_lock(&dentry->d_lock);
2130        if (atomic_read(&dentry->d_count) == 2)
2131                __d_drop(dentry);
2132        spin_unlock(&dentry->d_lock);
2133        spin_unlock(&dcache_lock);
2134}
2135
2136int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2137{
2138        int error = may_delete(dir, dentry, 1);
2139
2140        if (error)
2141                return error;
2142
2143        if (!dir->i_op || !dir->i_op->rmdir)
2144                return -EPERM;
2145
2146        DQUOT_INIT(dir);
2147
2148        mutex_lock(&dentry->d_inode->i_mutex);
2149        dentry_unhash(dentry);
2150        if (d_mountpoint(dentry))
2151                error = -EBUSY;
2152        else {
2153                error = security_inode_rmdir(dir, dentry);
2154                if (!error) {
2155                        error = dir->i_op->rmdir(dir, dentry);
2156                        if (!error)
2157                                dentry->d_inode->i_flags |= S_DEAD;
2158                }
2159        }
2160        mutex_unlock(&dentry->d_inode->i_mutex);
2161        if (!error) {
2162                d_delete(dentry);
2163        }
2164        dput(dentry);
2165
2166        return error;
2167}
2168
2169static long do_rmdir(int dfd, const char __user *pathname)
2170{
2171        int error = 0;
2172        char * name;
2173        struct dentry *dentry;
2174        struct nameidata nd;
2175
2176        error = user_path_parent(dfd, pathname, &nd, &name);
2177        if (error)
2178                return error;
2179
2180        switch(nd.last_type) {
2181                case LAST_DOTDOT:
2182                        error = -ENOTEMPTY;
2183                        goto exit1;
2184                case LAST_DOT:
2185                        error = -EINVAL;
2186                        goto exit1;
2187                case LAST_ROOT:
2188                        error = -EBUSY;
2189                        goto exit1;
2190        }
2191        mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2192        dentry = lookup_hash(&nd);
2193        error = PTR_ERR(dentry);
2194        if (IS_ERR(dentry))
2195                goto exit2;
2196        error = mnt_want_write(nd.path.mnt);
2197        if (error)
2198                goto exit3;
2199        error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
2200        mnt_drop_write(nd.path.mnt);
2201exit3:
2202        dput(dentry);
2203exit2:
2204        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2205exit1:
2206        path_put(&nd.path);
2207        putname(name);
2208        return error;
2209}
2210
2211asmlinkage long sys_rmdir(const char __user *pathname)
2212{
2213        return do_rmdir(AT_FDCWD, pathname);
2214}
2215
2216int vfs_unlink(struct inode *dir, struct dentry *dentry)
2217{
2218        int error = may_delete(dir, dentry, 0);
2219
2220        if (error)
2221                return error;
2222
2223        if (!dir->i_op || !dir->i_op->unlink)
2224                return -EPERM;
2225
2226        DQUOT_INIT(dir);
2227
2228        mutex_lock(&dentry->d_inode->i_mutex);
2229        if (d_mountpoint(dentry))
2230                error = -EBUSY;
2231        else {
2232                error = security_inode_unlink(dir, dentry);
2233                if (!error)
2234                        error = dir->i_op->unlink(dir, dentry);
2235        }
2236        mutex_unlock(&dentry->d_inode->i_mutex);
2237
2238        /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2239        if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2240                fsnotify_link_count(dentry->d_inode);
2241                d_delete(dentry);
2242        }
2243
2244        return error;
2245}
2246
2247/*
2248 * Make sure that the actual truncation of the file will occur outside its
2249 * directory's i_mutex.  Truncate can take a long time if there is a lot of
2250 * writeout happening, and we don't want to prevent access to the directory
2251 * while waiting on the I/O.
2252 */
2253static long do_unlinkat(int dfd, const char __user *pathname)
2254{
2255        int error;
2256        char *name;
2257        struct dentry *dentry;
2258        struct nameidata nd;
2259        struct inode *inode = NULL;
2260
2261        error = user_path_parent(dfd, pathname, &nd, &name);
2262        if (error)
2263                return error;
2264
2265        error = -EISDIR;
2266        if (nd.last_type != LAST_NORM)
2267                goto exit1;
2268        mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2269        dentry = lookup_hash(&nd);
2270        error = PTR_ERR(dentry);
2271        if (!IS_ERR(dentry)) {
2272                /* Why not before? Because we want correct error value */
2273                if (nd.last.name[nd.last.len])
2274                        goto slashes;
2275                inode = dentry->d_inode;
2276                if (inode)
2277                        atomic_inc(&inode->i_count);
2278                error = mnt_want_write(nd.path.mnt);
2279                if (error)
2280                        goto exit2;
2281                error = vfs_unlink(nd.path.dentry->d_inode, dentry);
2282                mnt_drop_write(nd.path.mnt);
2283        exit2:
2284                dput(dentry);
2285        }
2286        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2287        if (inode)
2288                iput(inode);    /* truncate the inode here */
2289exit1:
2290        path_put(&nd.path);
2291        putname(name);
2292        return error;
2293
2294slashes:
2295        error = !dentry->d_inode ? -ENOENT :
2296                S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2297        goto exit2;
2298}
2299
2300asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag)
2301{
2302        if ((flag & ~AT_REMOVEDIR) != 0)
2303                return -EINVAL;
2304
2305        if (flag & AT_REMOVEDIR)
2306                return do_rmdir(dfd, pathname);
2307
2308        return do_unlinkat(dfd, pathname);
2309}
2310
2311asmlinkage long sys_unlink(const char __user *pathname)
2312{
2313        return do_unlinkat(AT_FDCWD, pathname);
2314}
2315
2316int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
2317{
2318        int error = may_create(dir, dentry);
2319
2320        if (error)
2321                return error;
2322
2323        if (!dir->i_op || !dir->i_op->symlink)
2324                return -EPERM;
2325
2326        error = security_inode_symlink(dir, dentry, oldname);
2327        if (error)
2328                return error;
2329
2330        DQUOT_INIT(dir);
2331        error = dir->i_op->symlink(dir, dentry, oldname);
2332        if (!error)
2333                fsnotify_create(dir, dentry);
2334        return error;
2335}
2336
2337asmlinkage long sys_symlinkat(const char __user *oldname,
2338                              int newdfd, const char __user *newname)
2339{
2340        int error;
2341        char *from;
2342        char *to;
2343        struct dentry *dentry;
2344        struct nameidata nd;
2345
2346        from = getname(oldname);
2347        if (IS_ERR(from))
2348                return PTR_ERR(from);
2349
2350        error = user_path_parent(newdfd, newname, &nd, &to);
2351        if (error)
2352                goto out_putname;
2353
2354        dentry = lookup_create(&nd, 0);
2355        error = PTR_ERR(dentry);
2356        if (IS_ERR(dentry))
2357                goto out_unlock;
2358
2359        error = mnt_want_write(nd.path.mnt);
2360        if (error)
2361                goto out_dput;
2362        error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
2363        mnt_drop_write(nd.path.mnt);
2364out_dput:
2365        dput(dentry);
2366out_unlock:
2367        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2368        path_put(&nd.path);
2369        putname(to);
2370out_putname:
2371        putname(from);
2372        return error;
2373}
2374
2375asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname)
2376{
2377        return sys_symlinkat(oldname, AT_FDCWD, newname);
2378}
2379
2380int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2381{
2382        struct inode *inode = old_dentry->d_inode;
2383        int error;
2384
2385        if (!inode)
2386                return -ENOENT;
2387
2388        error = may_create(dir, new_dentry);
2389        if (error)
2390                return error;
2391
2392        if (dir->i_sb != inode->i_sb)
2393                return -EXDEV;
2394
2395        /*
2396         * A link to an append-only or immutable file cannot be created.
2397         */
2398        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2399                return -EPERM;
2400        if (!dir->i_op || !dir->i_op->link)
2401                return -EPERM;
2402        if (S_ISDIR(inode->i_mode))
2403                return -EPERM;
2404
2405        error = security_inode_link(old_dentry, dir, new_dentry);
2406        if (error)
2407                return error;
2408
2409        mutex_lock(&inode->i_mutex);
2410        DQUOT_INIT(dir);
2411        error = dir->i_op->link(old_dentry, dir, new_dentry);
2412        mutex_unlock(&inode->i_mutex);
2413        if (!error)
2414                fsnotify_link(dir, inode, new_dentry);
2415        return error;
2416}
2417
2418/*
2419 * Hardlinks are often used in delicate situations.  We avoid
2420 * security-related surprises by not following symlinks on the
2421 * newname.  --KAB
2422 *
2423 * We don't follow them on the oldname either to be compatible
2424 * with linux 2.0, and to avoid hard-linking to directories
2425 * and other special files.  --ADM
2426 */
2427asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
2428                           int newdfd, const char __user *newname,
2429                           int flags)
2430{
2431        struct dentry *new_dentry;
2432        struct nameidata nd;
2433        struct path old_path;
2434        int error;
2435        char *to;
2436
2437        if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
2438                return -EINVAL;
2439
2440        error = user_path_at(olddfd, oldname,
2441                             flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
2442                             &old_path);
2443        if (error)
2444                return error;
2445
2446        error = user_path_parent(newdfd, newname, &nd, &to);
2447        if (error)
2448                goto out;
2449        error = -EXDEV;
2450        if (old_path.mnt != nd.path.mnt)
2451                goto out_release;
2452        new_dentry = lookup_create(&nd, 0);
2453        error = PTR_ERR(new_dentry);
2454        if (IS_ERR(new_dentry))
2455                goto out_unlock;
2456        error = mnt_want_write(nd.path.mnt);
2457        if (error)
2458                goto out_dput;
2459        error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
2460        mnt_drop_write(nd.path.mnt);
2461out_dput:
2462        dput(new_dentry);
2463out_unlock:
2464        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2465out_release:
2466        path_put(&nd.path);
2467        putname(to);
2468out:
2469        path_put(&old_path);
2470
2471        return error;
2472}
2473
2474asmlinkage long sys_link(const char __user *oldname, const char __user *newname)
2475{
2476        return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2477}
2478
2479/*
2480 * The worst of all namespace operations - renaming directory. "Perverted"
2481 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2482 * Problems:
2483 *      a) we can get into loop creation. Check is done in is_subdir().
2484 *      b) race potential - two innocent renames can create a loop together.
2485 *         That's where 4.4 screws up. Current fix: serialization on
2486 *         sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2487 *         story.
2488 *      c) we have to lock _three_ objects - parents and victim (if it exists).
2489 *         And that - after we got ->i_mutex on parents (until then we don't know
2490 *         whether the target exists).  Solution: try to be smart with locking
2491 *         order for inodes.  We rely on the fact that tree topology may change
2492 *         only under ->s_vfs_rename_mutex _and_ that parent of the object we
2493 *         move will be locked.  Thus we can rank directories by the tree
2494 *         (ancestors first) and rank all non-directories after them.
2495 *         That works since everybody except rename does "lock parent, lookup,
2496 *         lock child" and rename is under ->s_vfs_rename_mutex.
2497 *         HOWEVER, it relies on the assumption that any object with ->lookup()
2498 *         has no more than 1 dentry.  If "hybrid" objects will ever appear,
2499 *         we'd better make sure that there's no link(2) for them.
2500 *      d) some filesystems don't support opened-but-unlinked directories,
2501 *         either because of layout or because they are not ready to deal with
2502 *         all cases correctly. The latter will be fixed (taking this sort of
2503 *         stuff into VFS), but the former is not going away. Solution: the same
2504 *         trick as in rmdir().
2505 *      e) conversion from fhandle to dentry may come in the wrong moment - when
2506 *         we are removing the target. Solution: we will have to grab ->i_mutex
2507 *         in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2508 *         ->i_mutex on parents, which works but leads to some truely excessive
2509 *         locking].
2510 */
2511static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2512                          struct inode *new_dir, struct dentry *new_dentry)
2513{
2514        int error = 0;
2515        struct inode *target;
2516
2517        /*
2518         * If we are going to change the parent - check write permissions,
2519         * we'll need to flip '..'.
2520         */
2521        if (new_dir != old_dir) {
2522                error = inode_permission(old_dentry->d_inode, MAY_WRITE);
2523                if (error)
2524                        return error;
2525        }
2526
2527        error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2528        if (error)
2529                return error;
2530
2531        target = new_dentry->d_inode;
2532        if (target) {
2533                mutex_lock(&target->i_mutex);
2534                dentry_unhash(new_dentry);
2535        }
2536        if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2537                error = -EBUSY;
2538        else 
2539                error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2540        if (target) {
2541                if (!error)
2542                        target->i_flags |= S_DEAD;
2543                mutex_unlock(&target->i_mutex);
2544                if (d_unhashed(new_dentry))
2545                        d_rehash(new_dentry);
2546                dput(new_dentry);
2547        }
2548        if (!error)
2549                if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2550                        d_move(old_dentry,new_dentry);
2551        return error;
2552}
2553
2554static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2555                            struct inode *new_dir, struct dentry *new_dentry)
2556{
2557        struct inode *target;
2558        int error;
2559
2560        error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2561        if (error)
2562                return error;
2563
2564        dget(new_dentry);
2565        target = new_dentry->d_inode;
2566        if (target)
2567                mutex_lock(&target->i_mutex);
2568        if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2569                error = -EBUSY;
2570        else
2571                error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2572        if (!error) {
2573                if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2574                        d_move(old_dentry, new_dentry);
2575        }
2576        if (target)
2577                mutex_unlock(&target->i_mutex);
2578        dput(new_dentry);
2579        return error;
2580}
2581
2582int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2583               struct inode *new_dir, struct dentry *new_dentry)
2584{
2585        int error;
2586        int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2587        const char *old_name;
2588
2589        if (old_dentry->d_inode == new_dentry->d_inode)
2590                return 0;
2591 
2592        error = may_delete(old_dir, old_dentry, is_dir);
2593        if (error)
2594                return error;
2595
2596        if (!new_dentry->d_inode)
2597                error = may_create(new_dir, new_dentry);
2598        else
2599                error = may_delete(new_dir, new_dentry, is_dir);
2600        if (error)
2601                return error;
2602
2603        if (!old_dir->i_op || !old_dir->i_op->rename)
2604                return -EPERM;
2605
2606        DQUOT_INIT(old_dir);
2607        DQUOT_INIT(new_dir);
2608
2609        old_name = fsnotify_oldname_init(old_dentry->d_name.name);
2610
2611        if (is_dir)
2612                error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2613        else
2614                error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2615        if (!error) {
2616                const char *new_name = old_dentry->d_name.name;
2617                fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
2618                              new_dentry->d_inode, old_dentry);
2619        }
2620        fsnotify_oldname_free(old_name);
2621
2622        return error;
2623}
2624
2625asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
2626                             int newdfd, const char __user *newname)
2627{
2628        struct dentry *old_dir, *new_dir;
2629        struct dentry *old_dentry, *new_dentry;
2630        struct dentry *trap;
2631        struct nameidata oldnd, newnd;
2632        char *from;
2633        char *to;
2634        int error;
2635
2636        error = user_path_parent(olddfd, oldname, &oldnd, &from);
2637        if (error)
2638                goto exit;
2639
2640        error = user_path_parent(newdfd, newname, &newnd, &to);
2641        if (error)
2642                goto exit1;
2643
2644        error = -EXDEV;
2645        if (oldnd.path.mnt != newnd.path.mnt)
2646                goto exit2;
2647
2648        old_dir = oldnd.path.dentry;
2649        error = -EBUSY;
2650        if (oldnd.last_type != LAST_NORM)
2651                goto exit2;
2652
2653        new_dir = newnd.path.dentry;
2654        if (newnd.last_type != LAST_NORM)
2655                goto exit2;
2656
2657        trap = lock_rename(new_dir, old_dir);
2658
2659        old_dentry = lookup_hash(&oldnd);
2660        error = PTR_ERR(old_dentry);
2661        if (IS_ERR(old_dentry))
2662                goto exit3;
2663        /* source must exist */
2664        error = -ENOENT;
2665        if (!old_dentry->d_inode)
2666                goto exit4;
2667        /* unless the source is a directory trailing slashes give -ENOTDIR */
2668        if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2669                error = -ENOTDIR;
2670                if (oldnd.last.name[oldnd.last.len])
2671                        goto exit4;
2672                if (newnd.last.name[newnd.last.len])
2673                        goto exit4;
2674        }
2675        /* source should not be ancestor of target */
2676        error = -EINVAL;
2677        if (old_dentry == trap)
2678                goto exit4;
2679        new_dentry = lookup_hash(&newnd);
2680        error = PTR_ERR(new_dentry);
2681        if (IS_ERR(new_dentry))
2682                goto exit4;
2683        /* target should not be an ancestor of source */
2684        error = -ENOTEMPTY;
2685        if (new_dentry == trap)
2686                goto exit5;
2687
2688        error = mnt_want_write(oldnd.path.mnt);
2689        if (error)
2690                goto exit5;
2691        error = vfs_rename(old_dir->d_inode, old_dentry,
2692                                   new_dir->d_inode, new_dentry);
2693        mnt_drop_write(oldnd.path.mnt);
2694exit5:
2695        dput(new_dentry);
2696exit4:
2697        dput(old_dentry);
2698exit3:
2699        unlock_rename(new_dir, old_dir);
2700exit2:
2701        path_put(&newnd.path);
2702        putname(to);
2703exit1:
2704        path_put(&oldnd.path);
2705        putname(from);
2706exit:
2707        return error;
2708}
2709
2710asmlinkage long sys_rename(const char __user *oldname, const char __user *newname)
2711{
2712        return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
2713}
2714
2715int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2716{
2717        int len;
2718
2719        len = PTR_ERR(link);
2720        if (IS_ERR(link))
2721                goto out;
2722
2723        len = strlen(link);
2724        if (len > (unsigned) buflen)
2725                len = buflen;
2726        if (copy_to_user(buffer, link, len))
2727                len = -EFAULT;
2728out:
2729        return len;
2730}
2731
2732/*
2733 * A helper for ->readlink().  This should be used *ONLY* for symlinks that
2734 * have ->follow_link() touching nd only in nd_set_link().  Using (or not
2735 * using) it for any given inode is up to filesystem.
2736 */
2737int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2738{
2739        struct nameidata nd;
2740        void *cookie;
2741        int res;
2742
2743        nd.depth = 0;
2744        cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
2745        if (IS_ERR(cookie))
2746                return PTR_ERR(cookie);
2747
2748        res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2749        if (dentry->d_inode->i_op->put_link)
2750                dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
2751        return res;
2752}
2753
2754int vfs_follow_link(struct nameidata *nd, const char *link)
2755{
2756        return __vfs_follow_link(nd, link);
2757}
2758
2759/* get the link contents into pagecache */
2760static char *page_getlink(struct dentry * dentry, struct page **ppage)
2761{
2762        struct page * page;
2763        struct address_space *mapping = dentry->d_inode->i_mapping;
2764        page = read_mapping_page(mapping, 0, NULL);
2765        if (IS_ERR(page))
2766                return (char*)page;
2767        *ppage = page;
2768        return kmap(page);
2769}
2770
2771int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2772{
2773        struct page *page = NULL;
2774        char *s = page_getlink(dentry, &page);
2775        int res = vfs_readlink(dentry,buffer,buflen,s);
2776        if (page) {
2777                kunmap(page);
2778                page_cache_release(page);
2779        }
2780        return res;
2781}
2782
2783void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
2784{
2785        struct page *page = NULL;
2786        nd_set_link(nd, page_getlink(dentry, &page));
2787        return page;
2788}
2789
2790void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2791{
2792        struct page *page = cookie;
2793
2794        if (page) {
2795                kunmap(page);
2796                page_cache_release(page);
2797        }
2798}
2799
2800int __page_symlink(struct inode *inode, const char *symname, int len,
2801                gfp_t gfp_mask)
2802{
2803        struct address_space *mapping = inode->i_mapping;
2804        struct page *page;
2805        void *fsdata;
2806        int err;
2807        char *kaddr;
2808
2809retry:
2810        err = pagecache_write_begin(NULL, mapping, 0, len-1,
2811                                AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
2812        if (err)
2813                goto fail;
2814
2815        kaddr = kmap_atomic(page, KM_USER0);
2816        memcpy(kaddr, symname, len-1);
2817        kunmap_atomic(kaddr, KM_USER0);
2818
2819        err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
2820                                                        page, fsdata);
2821        if (err < 0)
2822                goto fail;
2823        if (err < len-1)
2824                goto retry;
2825
2826        mark_inode_dirty(inode);
2827        return 0;
2828fail:
2829        return err;
2830}
2831
2832int page_symlink(struct inode *inode, const char *symname, int len)
2833{
2834        return __page_symlink(inode, symname, len,
2835                        mapping_gfp_mask(inode->i_mapping));
2836}
2837
2838const struct inode_operations page_symlink_inode_operations = {
2839        .readlink       = generic_readlink,
2840        .follow_link    = page_follow_link_light,
2841        .put_link       = page_put_link,
2842};
2843
2844EXPORT_SYMBOL(user_path_at);
2845EXPORT_SYMBOL(follow_down);
2846EXPORT_SYMBOL(follow_up);
2847EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2848EXPORT_SYMBOL(getname);
2849EXPORT_SYMBOL(lock_rename);
2850EXPORT_SYMBOL(lookup_one_len);
2851EXPORT_SYMBOL(page_follow_link_light);
2852EXPORT_SYMBOL(page_put_link);
2853EXPORT_SYMBOL(page_readlink);
2854EXPORT_SYMBOL(__page_symlink);
2855EXPORT_SYMBOL(page_symlink);
2856EXPORT_SYMBOL(page_symlink_inode_operations);
2857EXPORT_SYMBOL(path_lookup);
2858EXPORT_SYMBOL(vfs_path_lookup);
2859EXPORT_SYMBOL(inode_permission);
2860EXPORT_SYMBOL(vfs_permission);
2861EXPORT_SYMBOL(file_permission);
2862EXPORT_SYMBOL(unlock_rename);
2863EXPORT_SYMBOL(vfs_create);
2864EXPORT_SYMBOL(vfs_follow_link);
2865EXPORT_SYMBOL(vfs_link);
2866EXPORT_SYMBOL(vfs_mkdir);
2867EXPORT_SYMBOL(vfs_mknod);
2868EXPORT_SYMBOL(generic_permission);
2869EXPORT_SYMBOL(vfs_readlink);
2870EXPORT_SYMBOL(vfs_rename);
2871EXPORT_SYMBOL(vfs_rmdir);
2872EXPORT_SYMBOL(vfs_symlink);
2873EXPORT_SYMBOL(vfs_unlink);
2874EXPORT_SYMBOL(dentry_unhash);
2875EXPORT_SYMBOL(generic_readlink);
2876
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