Merge with master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
[sfrench/cifs-2.6.git] / fs / namei.c
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/dnotify.h>
25 #include <linux/smp_lock.h>
26 #include <linux/personality.h>
27 #include <linux/security.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <asm/namei.h>
32 #include <asm/uaccess.h>
33
34 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
35
36 /* [Feb-1997 T. Schoebel-Theuer]
37  * Fundamental changes in the pathname lookup mechanisms (namei)
38  * were necessary because of omirr.  The reason is that omirr needs
39  * to know the _real_ pathname, not the user-supplied one, in case
40  * of symlinks (and also when transname replacements occur).
41  *
42  * The new code replaces the old recursive symlink resolution with
43  * an iterative one (in case of non-nested symlink chains).  It does
44  * this with calls to <fs>_follow_link().
45  * As a side effect, dir_namei(), _namei() and follow_link() are now 
46  * replaced with a single function lookup_dentry() that can handle all 
47  * the special cases of the former code.
48  *
49  * With the new dcache, the pathname is stored at each inode, at least as
50  * long as the refcount of the inode is positive.  As a side effect, the
51  * size of the dcache depends on the inode cache and thus is dynamic.
52  *
53  * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
54  * resolution to correspond with current state of the code.
55  *
56  * Note that the symlink resolution is not *completely* iterative.
57  * There is still a significant amount of tail- and mid- recursion in
58  * the algorithm.  Also, note that <fs>_readlink() is not used in
59  * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
60  * may return different results than <fs>_follow_link().  Many virtual
61  * filesystems (including /proc) exhibit this behavior.
62  */
63
64 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
65  * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
66  * and the name already exists in form of a symlink, try to create the new
67  * name indicated by the symlink. The old code always complained that the
68  * name already exists, due to not following the symlink even if its target
69  * is nonexistent.  The new semantics affects also mknod() and link() when
70  * the name is a symlink pointing to a non-existant name.
71  *
72  * I don't know which semantics is the right one, since I have no access
73  * to standards. But I found by trial that HP-UX 9.0 has the full "new"
74  * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
75  * "old" one. Personally, I think the new semantics is much more logical.
76  * Note that "ln old new" where "new" is a symlink pointing to a non-existing
77  * file does succeed in both HP-UX and SunOs, but not in Solaris
78  * and in the old Linux semantics.
79  */
80
81 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
82  * semantics.  See the comments in "open_namei" and "do_link" below.
83  *
84  * [10-Sep-98 Alan Modra] Another symlink change.
85  */
86
87 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
88  *      inside the path - always follow.
89  *      in the last component in creation/removal/renaming - never follow.
90  *      if LOOKUP_FOLLOW passed - follow.
91  *      if the pathname has trailing slashes - follow.
92  *      otherwise - don't follow.
93  * (applied in that order).
94  *
95  * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
96  * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
97  * During the 2.4 we need to fix the userland stuff depending on it -
98  * hopefully we will be able to get rid of that wart in 2.5. So far only
99  * XEmacs seems to be relying on it...
100  */
101 /*
102  * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
103  * implemented.  Let's see if raised priority of ->s_vfs_rename_sem gives
104  * any extra contention...
105  */
106
107 /* In order to reduce some races, while at the same time doing additional
108  * checking and hopefully speeding things up, we copy filenames to the
109  * kernel data space before using them..
110  *
111  * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
112  * PATH_MAX includes the nul terminator --RR.
113  */
114 static inline int do_getname(const char __user *filename, char *page)
115 {
116         int retval;
117         unsigned long len = PATH_MAX;
118
119         if (!segment_eq(get_fs(), KERNEL_DS)) {
120                 if ((unsigned long) filename >= TASK_SIZE)
121                         return -EFAULT;
122                 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
123                         len = TASK_SIZE - (unsigned long) filename;
124         }
125
126         retval = strncpy_from_user(page, filename, len);
127         if (retval > 0) {
128                 if (retval < len)
129                         return 0;
130                 return -ENAMETOOLONG;
131         } else if (!retval)
132                 retval = -ENOENT;
133         return retval;
134 }
135
136 char * getname(const char __user * filename)
137 {
138         char *tmp, *result;
139
140         result = ERR_PTR(-ENOMEM);
141         tmp = __getname();
142         if (tmp)  {
143                 int retval = do_getname(filename, tmp);
144
145                 result = tmp;
146                 if (retval < 0) {
147                         __putname(tmp);
148                         result = ERR_PTR(retval);
149                 }
150         }
151         audit_getname(result);
152         return result;
153 }
154
155 #ifdef CONFIG_AUDITSYSCALL
156 void putname(const char *name)
157 {
158         if (unlikely(current->audit_context))
159                 audit_putname(name);
160         else
161                 __putname(name);
162 }
163 EXPORT_SYMBOL(putname);
164 #endif
165
166
167 /**
168  * generic_permission  -  check for access rights on a Posix-like filesystem
169  * @inode:      inode to check access rights for
170  * @mask:       right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
171  * @check_acl:  optional callback to check for Posix ACLs
172  *
173  * Used to check for read/write/execute permissions on a file.
174  * We use "fsuid" for this, letting us set arbitrary permissions
175  * for filesystem access without changing the "normal" uids which
176  * are used for other things..
177  */
178 int generic_permission(struct inode *inode, int mask,
179                 int (*check_acl)(struct inode *inode, int mask))
180 {
181         umode_t                 mode = inode->i_mode;
182
183         if (current->fsuid == inode->i_uid)
184                 mode >>= 6;
185         else {
186                 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
187                         int error = check_acl(inode, mask);
188                         if (error == -EACCES)
189                                 goto check_capabilities;
190                         else if (error != -EAGAIN)
191                                 return error;
192                 }
193
194                 if (in_group_p(inode->i_gid))
195                         mode >>= 3;
196         }
197
198         /*
199          * If the DACs are ok we don't need any capability check.
200          */
201         if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask))
202                 return 0;
203
204  check_capabilities:
205         /*
206          * Read/write DACs are always overridable.
207          * Executable DACs are overridable if at least one exec bit is set.
208          */
209         if (!(mask & MAY_EXEC) ||
210             (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
211                 if (capable(CAP_DAC_OVERRIDE))
212                         return 0;
213
214         /*
215          * Searching includes executable on directories, else just read.
216          */
217         if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
218                 if (capable(CAP_DAC_READ_SEARCH))
219                         return 0;
220
221         return -EACCES;
222 }
223
224 int permission(struct inode *inode, int mask, struct nameidata *nd)
225 {
226         int retval, submask;
227
228         if (mask & MAY_WRITE) {
229                 umode_t mode = inode->i_mode;
230
231                 /*
232                  * Nobody gets write access to a read-only fs.
233                  */
234                 if (IS_RDONLY(inode) &&
235                     (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
236                         return -EROFS;
237
238                 /*
239                  * Nobody gets write access to an immutable file.
240                  */
241                 if (IS_IMMUTABLE(inode))
242                         return -EACCES;
243         }
244
245
246         /* Ordinary permission routines do not understand MAY_APPEND. */
247         submask = mask & ~MAY_APPEND;
248         if (inode->i_op && inode->i_op->permission)
249                 retval = inode->i_op->permission(inode, submask, nd);
250         else
251                 retval = generic_permission(inode, submask, NULL);
252         if (retval)
253                 return retval;
254
255         return security_inode_permission(inode, mask, nd);
256 }
257
258 /*
259  * get_write_access() gets write permission for a file.
260  * put_write_access() releases this write permission.
261  * This is used for regular files.
262  * We cannot support write (and maybe mmap read-write shared) accesses and
263  * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
264  * can have the following values:
265  * 0: no writers, no VM_DENYWRITE mappings
266  * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
267  * > 0: (i_writecount) users are writing to the file.
268  *
269  * Normally we operate on that counter with atomic_{inc,dec} and it's safe
270  * except for the cases where we don't hold i_writecount yet. Then we need to
271  * use {get,deny}_write_access() - these functions check the sign and refuse
272  * to do the change if sign is wrong. Exclusion between them is provided by
273  * the inode->i_lock spinlock.
274  */
275
276 int get_write_access(struct inode * inode)
277 {
278         spin_lock(&inode->i_lock);
279         if (atomic_read(&inode->i_writecount) < 0) {
280                 spin_unlock(&inode->i_lock);
281                 return -ETXTBSY;
282         }
283         atomic_inc(&inode->i_writecount);
284         spin_unlock(&inode->i_lock);
285
286         return 0;
287 }
288
289 int deny_write_access(struct file * file)
290 {
291         struct inode *inode = file->f_dentry->d_inode;
292
293         spin_lock(&inode->i_lock);
294         if (atomic_read(&inode->i_writecount) > 0) {
295                 spin_unlock(&inode->i_lock);
296                 return -ETXTBSY;
297         }
298         atomic_dec(&inode->i_writecount);
299         spin_unlock(&inode->i_lock);
300
301         return 0;
302 }
303
304 void path_release(struct nameidata *nd)
305 {
306         dput(nd->dentry);
307         mntput(nd->mnt);
308 }
309
310 /*
311  * umount() mustn't call path_release()/mntput() as that would clear
312  * mnt_expiry_mark
313  */
314 void path_release_on_umount(struct nameidata *nd)
315 {
316         dput(nd->dentry);
317         _mntput(nd->mnt);
318 }
319
320 /*
321  * Internal lookup() using the new generic dcache.
322  * SMP-safe
323  */
324 static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
325 {
326         struct dentry * dentry = __d_lookup(parent, name);
327
328         /* lockess __d_lookup may fail due to concurrent d_move() 
329          * in some unrelated directory, so try with d_lookup
330          */
331         if (!dentry)
332                 dentry = d_lookup(parent, name);
333
334         if (dentry && dentry->d_op && dentry->d_op->d_revalidate) {
335                 if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) {
336                         dput(dentry);
337                         dentry = NULL;
338                 }
339         }
340         return dentry;
341 }
342
343 /*
344  * Short-cut version of permission(), for calling by
345  * path_walk(), when dcache lock is held.  Combines parts
346  * of permission() and generic_permission(), and tests ONLY for
347  * MAY_EXEC permission.
348  *
349  * If appropriate, check DAC only.  If not appropriate, or
350  * short-cut DAC fails, then call permission() to do more
351  * complete permission check.
352  */
353 static inline int exec_permission_lite(struct inode *inode,
354                                        struct nameidata *nd)
355 {
356         umode_t mode = inode->i_mode;
357
358         if (inode->i_op && inode->i_op->permission)
359                 return -EAGAIN;
360
361         if (current->fsuid == inode->i_uid)
362                 mode >>= 6;
363         else if (in_group_p(inode->i_gid))
364                 mode >>= 3;
365
366         if (mode & MAY_EXEC)
367                 goto ok;
368
369         if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
370                 goto ok;
371
372         if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
373                 goto ok;
374
375         if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
376                 goto ok;
377
378         return -EACCES;
379 ok:
380         return security_inode_permission(inode, MAY_EXEC, nd);
381 }
382
383 /*
384  * This is called when everything else fails, and we actually have
385  * to go to the low-level filesystem to find out what we should do..
386  *
387  * We get the directory semaphore, and after getting that we also
388  * make sure that nobody added the entry to the dcache in the meantime..
389  * SMP-safe
390  */
391 static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
392 {
393         struct dentry * result;
394         struct inode *dir = parent->d_inode;
395
396         down(&dir->i_sem);
397         /*
398          * First re-do the cached lookup just in case it was created
399          * while we waited for the directory semaphore..
400          *
401          * FIXME! This could use version numbering or similar to
402          * avoid unnecessary cache lookups.
403          *
404          * The "dcache_lock" is purely to protect the RCU list walker
405          * from concurrent renames at this point (we mustn't get false
406          * negatives from the RCU list walk here, unlike the optimistic
407          * fast walk).
408          *
409          * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
410          */
411         result = d_lookup(parent, name);
412         if (!result) {
413                 struct dentry * dentry = d_alloc(parent, name);
414                 result = ERR_PTR(-ENOMEM);
415                 if (dentry) {
416                         result = dir->i_op->lookup(dir, dentry, nd);
417                         if (result)
418                                 dput(dentry);
419                         else
420                                 result = dentry;
421                 }
422                 up(&dir->i_sem);
423                 return result;
424         }
425
426         /*
427          * Uhhuh! Nasty case: the cache was re-populated while
428          * we waited on the semaphore. Need to revalidate.
429          */
430         up(&dir->i_sem);
431         if (result->d_op && result->d_op->d_revalidate) {
432                 if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) {
433                         dput(result);
434                         result = ERR_PTR(-ENOENT);
435                 }
436         }
437         return result;
438 }
439
440 static int __emul_lookup_dentry(const char *, struct nameidata *);
441
442 /* SMP-safe */
443 static inline int
444 walk_init_root(const char *name, struct nameidata *nd)
445 {
446         read_lock(&current->fs->lock);
447         if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
448                 nd->mnt = mntget(current->fs->altrootmnt);
449                 nd->dentry = dget(current->fs->altroot);
450                 read_unlock(&current->fs->lock);
451                 if (__emul_lookup_dentry(name,nd))
452                         return 0;
453                 read_lock(&current->fs->lock);
454         }
455         nd->mnt = mntget(current->fs->rootmnt);
456         nd->dentry = dget(current->fs->root);
457         read_unlock(&current->fs->lock);
458         return 1;
459 }
460
461 static inline int __vfs_follow_link(struct nameidata *nd, const char *link)
462 {
463         int res = 0;
464         char *name;
465         if (IS_ERR(link))
466                 goto fail;
467
468         if (*link == '/') {
469                 path_release(nd);
470                 if (!walk_init_root(link, nd))
471                         /* weird __emul_prefix() stuff did it */
472                         goto out;
473         }
474         res = link_path_walk(link, nd);
475 out:
476         if (nd->depth || res || nd->last_type!=LAST_NORM)
477                 return res;
478         /*
479          * If it is an iterative symlinks resolution in open_namei() we
480          * have to copy the last component. And all that crap because of
481          * bloody create() on broken symlinks. Furrfu...
482          */
483         name = __getname();
484         if (unlikely(!name)) {
485                 path_release(nd);
486                 return -ENOMEM;
487         }
488         strcpy(name, nd->last.name);
489         nd->last.name = name;
490         return 0;
491 fail:
492         path_release(nd);
493         return PTR_ERR(link);
494 }
495
496 static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
497 {
498         int error;
499
500         touch_atime(nd->mnt, dentry);
501         nd_set_link(nd, NULL);
502         error = dentry->d_inode->i_op->follow_link(dentry, nd);
503         if (!error) {
504                 char *s = nd_get_link(nd);
505                 if (s)
506                         error = __vfs_follow_link(nd, s);
507                 if (dentry->d_inode->i_op->put_link)
508                         dentry->d_inode->i_op->put_link(dentry, nd);
509         }
510
511         return error;
512 }
513
514 /*
515  * This limits recursive symlink follows to 8, while
516  * limiting consecutive symlinks to 40.
517  *
518  * Without that kind of total limit, nasty chains of consecutive
519  * symlinks can cause almost arbitrarily long lookups. 
520  */
521 static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd)
522 {
523         int err = -ELOOP;
524         if (current->link_count >= MAX_NESTED_LINKS)
525                 goto loop;
526         if (current->total_link_count >= 40)
527                 goto loop;
528         BUG_ON(nd->depth >= MAX_NESTED_LINKS);
529         cond_resched();
530         err = security_inode_follow_link(dentry, nd);
531         if (err)
532                 goto loop;
533         current->link_count++;
534         current->total_link_count++;
535         nd->depth++;
536         err = __do_follow_link(dentry, nd);
537         current->link_count--;
538         nd->depth--;
539         return err;
540 loop:
541         path_release(nd);
542         return err;
543 }
544
545 int follow_up(struct vfsmount **mnt, struct dentry **dentry)
546 {
547         struct vfsmount *parent;
548         struct dentry *mountpoint;
549         spin_lock(&vfsmount_lock);
550         parent=(*mnt)->mnt_parent;
551         if (parent == *mnt) {
552                 spin_unlock(&vfsmount_lock);
553                 return 0;
554         }
555         mntget(parent);
556         mountpoint=dget((*mnt)->mnt_mountpoint);
557         spin_unlock(&vfsmount_lock);
558         dput(*dentry);
559         *dentry = mountpoint;
560         mntput(*mnt);
561         *mnt = parent;
562         return 1;
563 }
564
565 /* no need for dcache_lock, as serialization is taken care in
566  * namespace.c
567  */
568 static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
569 {
570         int res = 0;
571         while (d_mountpoint(*dentry)) {
572                 struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
573                 if (!mounted)
574                         break;
575                 mntput(*mnt);
576                 *mnt = mounted;
577                 dput(*dentry);
578                 *dentry = dget(mounted->mnt_root);
579                 res = 1;
580         }
581         return res;
582 }
583
584 /* no need for dcache_lock, as serialization is taken care in
585  * namespace.c
586  */
587 static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry)
588 {
589         struct vfsmount *mounted;
590
591         mounted = lookup_mnt(*mnt, *dentry);
592         if (mounted) {
593                 mntput(*mnt);
594                 *mnt = mounted;
595                 dput(*dentry);
596                 *dentry = dget(mounted->mnt_root);
597                 return 1;
598         }
599         return 0;
600 }
601
602 int follow_down(struct vfsmount **mnt, struct dentry **dentry)
603 {
604         return __follow_down(mnt,dentry);
605 }
606  
607 static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
608 {
609         while(1) {
610                 struct vfsmount *parent;
611                 struct dentry *old = *dentry;
612
613                 read_lock(&current->fs->lock);
614                 if (*dentry == current->fs->root &&
615                     *mnt == current->fs->rootmnt) {
616                         read_unlock(&current->fs->lock);
617                         break;
618                 }
619                 read_unlock(&current->fs->lock);
620                 spin_lock(&dcache_lock);
621                 if (*dentry != (*mnt)->mnt_root) {
622                         *dentry = dget((*dentry)->d_parent);
623                         spin_unlock(&dcache_lock);
624                         dput(old);
625                         break;
626                 }
627                 spin_unlock(&dcache_lock);
628                 spin_lock(&vfsmount_lock);
629                 parent = (*mnt)->mnt_parent;
630                 if (parent == *mnt) {
631                         spin_unlock(&vfsmount_lock);
632                         break;
633                 }
634                 mntget(parent);
635                 *dentry = dget((*mnt)->mnt_mountpoint);
636                 spin_unlock(&vfsmount_lock);
637                 dput(old);
638                 mntput(*mnt);
639                 *mnt = parent;
640         }
641         follow_mount(mnt, dentry);
642 }
643
644 struct path {
645         struct vfsmount *mnt;
646         struct dentry *dentry;
647 };
648
649 /*
650  *  It's more convoluted than I'd like it to be, but... it's still fairly
651  *  small and for now I'd prefer to have fast path as straight as possible.
652  *  It _is_ time-critical.
653  */
654 static int do_lookup(struct nameidata *nd, struct qstr *name,
655                      struct path *path)
656 {
657         struct vfsmount *mnt = nd->mnt;
658         struct dentry *dentry = __d_lookup(nd->dentry, name);
659
660         if (!dentry)
661                 goto need_lookup;
662         if (dentry->d_op && dentry->d_op->d_revalidate)
663                 goto need_revalidate;
664 done:
665         path->mnt = mnt;
666         path->dentry = dentry;
667         return 0;
668
669 need_lookup:
670         dentry = real_lookup(nd->dentry, name, nd);
671         if (IS_ERR(dentry))
672                 goto fail;
673         goto done;
674
675 need_revalidate:
676         if (dentry->d_op->d_revalidate(dentry, nd))
677                 goto done;
678         if (d_invalidate(dentry))
679                 goto done;
680         dput(dentry);
681         goto need_lookup;
682
683 fail:
684         return PTR_ERR(dentry);
685 }
686
687 /*
688  * Name resolution.
689  * This is the basic name resolution function, turning a pathname into
690  * the final dentry. We expect 'base' to be positive and a directory.
691  *
692  * Returns 0 and nd will have valid dentry and mnt on success.
693  * Returns error and drops reference to input namei data on failure.
694  */
695 static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
696 {
697         struct path next;
698         struct inode *inode;
699         int err;
700         unsigned int lookup_flags = nd->flags;
701         
702         while (*name=='/')
703                 name++;
704         if (!*name)
705                 goto return_reval;
706
707         inode = nd->dentry->d_inode;
708         if (nd->depth)
709                 lookup_flags = LOOKUP_FOLLOW;
710
711         /* At this point we know we have a real path component. */
712         for(;;) {
713                 unsigned long hash;
714                 struct qstr this;
715                 unsigned int c;
716
717                 err = exec_permission_lite(inode, nd);
718                 if (err == -EAGAIN) { 
719                         err = permission(inode, MAY_EXEC, nd);
720                 }
721                 if (err)
722                         break;
723
724                 this.name = name;
725                 c = *(const unsigned char *)name;
726
727                 hash = init_name_hash();
728                 do {
729                         name++;
730                         hash = partial_name_hash(c, hash);
731                         c = *(const unsigned char *)name;
732                 } while (c && (c != '/'));
733                 this.len = name - (const char *) this.name;
734                 this.hash = end_name_hash(hash);
735
736                 /* remove trailing slashes? */
737                 if (!c)
738                         goto last_component;
739                 while (*++name == '/');
740                 if (!*name)
741                         goto last_with_slashes;
742
743                 /*
744                  * "." and ".." are special - ".." especially so because it has
745                  * to be able to know about the current root directory and
746                  * parent relationships.
747                  */
748                 if (this.name[0] == '.') switch (this.len) {
749                         default:
750                                 break;
751                         case 2: 
752                                 if (this.name[1] != '.')
753                                         break;
754                                 follow_dotdot(&nd->mnt, &nd->dentry);
755                                 inode = nd->dentry->d_inode;
756                                 /* fallthrough */
757                         case 1:
758                                 continue;
759                 }
760                 /*
761                  * See if the low-level filesystem might want
762                  * to use its own hash..
763                  */
764                 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
765                         err = nd->dentry->d_op->d_hash(nd->dentry, &this);
766                         if (err < 0)
767                                 break;
768                 }
769                 nd->flags |= LOOKUP_CONTINUE;
770                 /* This does the actual lookups.. */
771                 err = do_lookup(nd, &this, &next);
772                 if (err)
773                         break;
774                 /* Check mountpoints.. */
775                 follow_mount(&next.mnt, &next.dentry);
776
777                 err = -ENOENT;
778                 inode = next.dentry->d_inode;
779                 if (!inode)
780                         goto out_dput;
781                 err = -ENOTDIR; 
782                 if (!inode->i_op)
783                         goto out_dput;
784
785                 if (inode->i_op->follow_link) {
786                         mntget(next.mnt);
787                         err = do_follow_link(next.dentry, nd);
788                         dput(next.dentry);
789                         mntput(next.mnt);
790                         if (err)
791                                 goto return_err;
792                         err = -ENOENT;
793                         inode = nd->dentry->d_inode;
794                         if (!inode)
795                                 break;
796                         err = -ENOTDIR; 
797                         if (!inode->i_op)
798                                 break;
799                 } else {
800                         dput(nd->dentry);
801                         nd->mnt = next.mnt;
802                         nd->dentry = next.dentry;
803                 }
804                 err = -ENOTDIR; 
805                 if (!inode->i_op->lookup)
806                         break;
807                 continue;
808                 /* here ends the main loop */
809
810 last_with_slashes:
811                 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
812 last_component:
813                 nd->flags &= ~LOOKUP_CONTINUE;
814                 if (lookup_flags & LOOKUP_PARENT)
815                         goto lookup_parent;
816                 if (this.name[0] == '.') switch (this.len) {
817                         default:
818                                 break;
819                         case 2: 
820                                 if (this.name[1] != '.')
821                                         break;
822                                 follow_dotdot(&nd->mnt, &nd->dentry);
823                                 inode = nd->dentry->d_inode;
824                                 /* fallthrough */
825                         case 1:
826                                 goto return_reval;
827                 }
828                 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
829                         err = nd->dentry->d_op->d_hash(nd->dentry, &this);
830                         if (err < 0)
831                                 break;
832                 }
833                 err = do_lookup(nd, &this, &next);
834                 if (err)
835                         break;
836                 follow_mount(&next.mnt, &next.dentry);
837                 inode = next.dentry->d_inode;
838                 if ((lookup_flags & LOOKUP_FOLLOW)
839                     && inode && inode->i_op && inode->i_op->follow_link) {
840                         mntget(next.mnt);
841                         err = do_follow_link(next.dentry, nd);
842                         dput(next.dentry);
843                         mntput(next.mnt);
844                         if (err)
845                                 goto return_err;
846                         inode = nd->dentry->d_inode;
847                 } else {
848                         dput(nd->dentry);
849                         nd->mnt = next.mnt;
850                         nd->dentry = next.dentry;
851                 }
852                 err = -ENOENT;
853                 if (!inode)
854                         break;
855                 if (lookup_flags & LOOKUP_DIRECTORY) {
856                         err = -ENOTDIR; 
857                         if (!inode->i_op || !inode->i_op->lookup)
858                                 break;
859                 }
860                 goto return_base;
861 lookup_parent:
862                 nd->last = this;
863                 nd->last_type = LAST_NORM;
864                 if (this.name[0] != '.')
865                         goto return_base;
866                 if (this.len == 1)
867                         nd->last_type = LAST_DOT;
868                 else if (this.len == 2 && this.name[1] == '.')
869                         nd->last_type = LAST_DOTDOT;
870                 else
871                         goto return_base;
872 return_reval:
873                 /*
874                  * We bypassed the ordinary revalidation routines.
875                  * We may need to check the cached dentry for staleness.
876                  */
877                 if (nd->dentry && nd->dentry->d_sb &&
878                     (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
879                         err = -ESTALE;
880                         /* Note: we do not d_invalidate() */
881                         if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
882                                 break;
883                 }
884 return_base:
885                 return 0;
886 out_dput:
887                 dput(next.dentry);
888                 break;
889         }
890         path_release(nd);
891 return_err:
892         return err;
893 }
894
895 /*
896  * Wrapper to retry pathname resolution whenever the underlying
897  * file system returns an ESTALE.
898  *
899  * Retry the whole path once, forcing real lookup requests
900  * instead of relying on the dcache.
901  */
902 int fastcall link_path_walk(const char *name, struct nameidata *nd)
903 {
904         struct nameidata save = *nd;
905         int result;
906
907         /* make sure the stuff we saved doesn't go away */
908         dget(save.dentry);
909         mntget(save.mnt);
910
911         result = __link_path_walk(name, nd);
912         if (result == -ESTALE) {
913                 *nd = save;
914                 dget(nd->dentry);
915                 mntget(nd->mnt);
916                 nd->flags |= LOOKUP_REVAL;
917                 result = __link_path_walk(name, nd);
918         }
919
920         dput(save.dentry);
921         mntput(save.mnt);
922
923         return result;
924 }
925
926 int fastcall path_walk(const char * name, struct nameidata *nd)
927 {
928         current->total_link_count = 0;
929         return link_path_walk(name, nd);
930 }
931
932 /* 
933  * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
934  * everything is done. Returns 0 and drops input nd, if lookup failed;
935  */
936 static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
937 {
938         if (path_walk(name, nd))
939                 return 0;               /* something went wrong... */
940
941         if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
942                 struct dentry *old_dentry = nd->dentry;
943                 struct vfsmount *old_mnt = nd->mnt;
944                 struct qstr last = nd->last;
945                 int last_type = nd->last_type;
946                 /*
947                  * NAME was not found in alternate root or it's a directory.  Try to find
948                  * it in the normal root:
949                  */
950                 nd->last_type = LAST_ROOT;
951                 read_lock(&current->fs->lock);
952                 nd->mnt = mntget(current->fs->rootmnt);
953                 nd->dentry = dget(current->fs->root);
954                 read_unlock(&current->fs->lock);
955                 if (path_walk(name, nd) == 0) {
956                         if (nd->dentry->d_inode) {
957                                 dput(old_dentry);
958                                 mntput(old_mnt);
959                                 return 1;
960                         }
961                         path_release(nd);
962                 }
963                 nd->dentry = old_dentry;
964                 nd->mnt = old_mnt;
965                 nd->last = last;
966                 nd->last_type = last_type;
967         }
968         return 1;
969 }
970
971 void set_fs_altroot(void)
972 {
973         char *emul = __emul_prefix();
974         struct nameidata nd;
975         struct vfsmount *mnt = NULL, *oldmnt;
976         struct dentry *dentry = NULL, *olddentry;
977         int err;
978
979         if (!emul)
980                 goto set_it;
981         err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
982         if (!err) {
983                 mnt = nd.mnt;
984                 dentry = nd.dentry;
985         }
986 set_it:
987         write_lock(&current->fs->lock);
988         oldmnt = current->fs->altrootmnt;
989         olddentry = current->fs->altroot;
990         current->fs->altrootmnt = mnt;
991         current->fs->altroot = dentry;
992         write_unlock(&current->fs->lock);
993         if (olddentry) {
994                 dput(olddentry);
995                 mntput(oldmnt);
996         }
997 }
998
999 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1000 int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd)
1001 {
1002         int retval = 0;
1003
1004         nd->last_type = LAST_ROOT; /* if there are only slashes... */
1005         nd->flags = flags;
1006         nd->depth = 0;
1007
1008         read_lock(&current->fs->lock);
1009         if (*name=='/') {
1010                 if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
1011                         nd->mnt = mntget(current->fs->altrootmnt);
1012                         nd->dentry = dget(current->fs->altroot);
1013                         read_unlock(&current->fs->lock);
1014                         if (__emul_lookup_dentry(name,nd))
1015                                 goto out; /* found in altroot */
1016                         read_lock(&current->fs->lock);
1017                 }
1018                 nd->mnt = mntget(current->fs->rootmnt);
1019                 nd->dentry = dget(current->fs->root);
1020         } else {
1021                 nd->mnt = mntget(current->fs->pwdmnt);
1022                 nd->dentry = dget(current->fs->pwd);
1023         }
1024         read_unlock(&current->fs->lock);
1025         current->total_link_count = 0;
1026         retval = link_path_walk(name, nd);
1027 out:
1028         if (unlikely(current->audit_context
1029                      && nd && nd->dentry && nd->dentry->d_inode))
1030                 audit_inode(name, nd->dentry->d_inode);
1031         return retval;
1032 }
1033
1034 /*
1035  * Restricted form of lookup. Doesn't follow links, single-component only,
1036  * needs parent already locked. Doesn't follow mounts.
1037  * SMP-safe.
1038  */
1039 static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
1040 {
1041         struct dentry * dentry;
1042         struct inode *inode;
1043         int err;
1044
1045         inode = base->d_inode;
1046         err = permission(inode, MAY_EXEC, nd);
1047         dentry = ERR_PTR(err);
1048         if (err)
1049                 goto out;
1050
1051         /*
1052          * See if the low-level filesystem might want
1053          * to use its own hash..
1054          */
1055         if (base->d_op && base->d_op->d_hash) {
1056                 err = base->d_op->d_hash(base, name);
1057                 dentry = ERR_PTR(err);
1058                 if (err < 0)
1059                         goto out;
1060         }
1061
1062         dentry = cached_lookup(base, name, nd);
1063         if (!dentry) {
1064                 struct dentry *new = d_alloc(base, name);
1065                 dentry = ERR_PTR(-ENOMEM);
1066                 if (!new)
1067                         goto out;
1068                 dentry = inode->i_op->lookup(inode, new, nd);
1069                 if (!dentry)
1070                         dentry = new;
1071                 else
1072                         dput(new);
1073         }
1074 out:
1075         return dentry;
1076 }
1077
1078 struct dentry * lookup_hash(struct qstr *name, struct dentry * base)
1079 {
1080         return __lookup_hash(name, base, NULL);
1081 }
1082
1083 /* SMP-safe */
1084 struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
1085 {
1086         unsigned long hash;
1087         struct qstr this;
1088         unsigned int c;
1089
1090         this.name = name;
1091         this.len = len;
1092         if (!len)
1093                 goto access;
1094
1095         hash = init_name_hash();
1096         while (len--) {
1097                 c = *(const unsigned char *)name++;
1098                 if (c == '/' || c == '\0')
1099                         goto access;
1100                 hash = partial_name_hash(c, hash);
1101         }
1102         this.hash = end_name_hash(hash);
1103
1104         return lookup_hash(&this, base);
1105 access:
1106         return ERR_PTR(-EACCES);
1107 }
1108
1109 /*
1110  *      namei()
1111  *
1112  * is used by most simple commands to get the inode of a specified name.
1113  * Open, link etc use their own routines, but this is enough for things
1114  * like 'chmod' etc.
1115  *
1116  * namei exists in two versions: namei/lnamei. The only difference is
1117  * that namei follows links, while lnamei does not.
1118  * SMP-safe
1119  */
1120 int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
1121 {
1122         char *tmp = getname(name);
1123         int err = PTR_ERR(tmp);
1124
1125         if (!IS_ERR(tmp)) {
1126                 err = path_lookup(tmp, flags, nd);
1127                 putname(tmp);
1128         }
1129         return err;
1130 }
1131
1132 /*
1133  * It's inline, so penalty for filesystems that don't use sticky bit is
1134  * minimal.
1135  */
1136 static inline int check_sticky(struct inode *dir, struct inode *inode)
1137 {
1138         if (!(dir->i_mode & S_ISVTX))
1139                 return 0;
1140         if (inode->i_uid == current->fsuid)
1141                 return 0;
1142         if (dir->i_uid == current->fsuid)
1143                 return 0;
1144         return !capable(CAP_FOWNER);
1145 }
1146
1147 /*
1148  *      Check whether we can remove a link victim from directory dir, check
1149  *  whether the type of victim is right.
1150  *  1. We can't do it if dir is read-only (done in permission())
1151  *  2. We should have write and exec permissions on dir
1152  *  3. We can't remove anything from append-only dir
1153  *  4. We can't do anything with immutable dir (done in permission())
1154  *  5. If the sticky bit on dir is set we should either
1155  *      a. be owner of dir, or
1156  *      b. be owner of victim, or
1157  *      c. have CAP_FOWNER capability
1158  *  6. If the victim is append-only or immutable we can't do antyhing with
1159  *     links pointing to it.
1160  *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1161  *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1162  *  9. We can't remove a root or mountpoint.
1163  * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1164  *     nfs_async_unlink().
1165  */
1166 static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1167 {
1168         int error;
1169
1170         if (!victim->d_inode)
1171                 return -ENOENT;
1172
1173         BUG_ON(victim->d_parent->d_inode != dir);
1174
1175         error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
1176         if (error)
1177                 return error;
1178         if (IS_APPEND(dir))
1179                 return -EPERM;
1180         if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1181             IS_IMMUTABLE(victim->d_inode))
1182                 return -EPERM;
1183         if (isdir) {
1184                 if (!S_ISDIR(victim->d_inode->i_mode))
1185                         return -ENOTDIR;
1186                 if (IS_ROOT(victim))
1187                         return -EBUSY;
1188         } else if (S_ISDIR(victim->d_inode->i_mode))
1189                 return -EISDIR;
1190         if (IS_DEADDIR(dir))
1191                 return -ENOENT;
1192         if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1193                 return -EBUSY;
1194         return 0;
1195 }
1196
1197 /*      Check whether we can create an object with dentry child in directory
1198  *  dir.
1199  *  1. We can't do it if child already exists (open has special treatment for
1200  *     this case, but since we are inlined it's OK)
1201  *  2. We can't do it if dir is read-only (done in permission())
1202  *  3. We should have write and exec permissions on dir
1203  *  4. We can't do it if dir is immutable (done in permission())
1204  */
1205 static inline int may_create(struct inode *dir, struct dentry *child,
1206                              struct nameidata *nd)
1207 {
1208         if (child->d_inode)
1209                 return -EEXIST;
1210         if (IS_DEADDIR(dir))
1211                 return -ENOENT;
1212         return permission(dir,MAY_WRITE | MAY_EXEC, nd);
1213 }
1214
1215 /* 
1216  * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
1217  * reasons.
1218  *
1219  * O_DIRECTORY translates into forcing a directory lookup.
1220  */
1221 static inline int lookup_flags(unsigned int f)
1222 {
1223         unsigned long retval = LOOKUP_FOLLOW;
1224
1225         if (f & O_NOFOLLOW)
1226                 retval &= ~LOOKUP_FOLLOW;
1227         
1228         if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
1229                 retval &= ~LOOKUP_FOLLOW;
1230         
1231         if (f & O_DIRECTORY)
1232                 retval |= LOOKUP_DIRECTORY;
1233
1234         return retval;
1235 }
1236
1237 /*
1238  * p1 and p2 should be directories on the same fs.
1239  */
1240 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1241 {
1242         struct dentry *p;
1243
1244         if (p1 == p2) {
1245                 down(&p1->d_inode->i_sem);
1246                 return NULL;
1247         }
1248
1249         down(&p1->d_inode->i_sb->s_vfs_rename_sem);
1250
1251         for (p = p1; p->d_parent != p; p = p->d_parent) {
1252                 if (p->d_parent == p2) {
1253                         down(&p2->d_inode->i_sem);
1254                         down(&p1->d_inode->i_sem);
1255                         return p;
1256                 }
1257         }
1258
1259         for (p = p2; p->d_parent != p; p = p->d_parent) {
1260                 if (p->d_parent == p1) {
1261                         down(&p1->d_inode->i_sem);
1262                         down(&p2->d_inode->i_sem);
1263                         return p;
1264                 }
1265         }
1266
1267         down(&p1->d_inode->i_sem);
1268         down(&p2->d_inode->i_sem);
1269         return NULL;
1270 }
1271
1272 void unlock_rename(struct dentry *p1, struct dentry *p2)
1273 {
1274         up(&p1->d_inode->i_sem);
1275         if (p1 != p2) {
1276                 up(&p2->d_inode->i_sem);
1277                 up(&p1->d_inode->i_sb->s_vfs_rename_sem);
1278         }
1279 }
1280
1281 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1282                 struct nameidata *nd)
1283 {
1284         int error = may_create(dir, dentry, nd);
1285
1286         if (error)
1287                 return error;
1288
1289         if (!dir->i_op || !dir->i_op->create)
1290                 return -EACCES; /* shouldn't it be ENOSYS? */
1291         mode &= S_IALLUGO;
1292         mode |= S_IFREG;
1293         error = security_inode_create(dir, dentry, mode);
1294         if (error)
1295                 return error;
1296         DQUOT_INIT(dir);
1297         error = dir->i_op->create(dir, dentry, mode, nd);
1298         if (!error) {
1299                 inode_dir_notify(dir, DN_CREATE);
1300                 security_inode_post_create(dir, dentry, mode);
1301         }
1302         return error;
1303 }
1304
1305 int may_open(struct nameidata *nd, int acc_mode, int flag)
1306 {
1307         struct dentry *dentry = nd->dentry;
1308         struct inode *inode = dentry->d_inode;
1309         int error;
1310
1311         if (!inode)
1312                 return -ENOENT;
1313
1314         if (S_ISLNK(inode->i_mode))
1315                 return -ELOOP;
1316         
1317         if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
1318                 return -EISDIR;
1319
1320         error = permission(inode, acc_mode, nd);
1321         if (error)
1322                 return error;
1323
1324         /*
1325          * FIFO's, sockets and device files are special: they don't
1326          * actually live on the filesystem itself, and as such you
1327          * can write to them even if the filesystem is read-only.
1328          */
1329         if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
1330                 flag &= ~O_TRUNC;
1331         } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
1332                 if (nd->mnt->mnt_flags & MNT_NODEV)
1333                         return -EACCES;
1334
1335                 flag &= ~O_TRUNC;
1336         } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
1337                 return -EROFS;
1338         /*
1339          * An append-only file must be opened in append mode for writing.
1340          */
1341         if (IS_APPEND(inode)) {
1342                 if  ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1343                         return -EPERM;
1344                 if (flag & O_TRUNC)
1345                         return -EPERM;
1346         }
1347
1348         /* O_NOATIME can only be set by the owner or superuser */
1349         if (flag & O_NOATIME)
1350                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
1351                         return -EPERM;
1352
1353         /*
1354          * Ensure there are no outstanding leases on the file.
1355          */
1356         error = break_lease(inode, flag);
1357         if (error)
1358                 return error;
1359
1360         if (flag & O_TRUNC) {
1361                 error = get_write_access(inode);
1362                 if (error)
1363                         return error;
1364
1365                 /*
1366                  * Refuse to truncate files with mandatory locks held on them.
1367                  */
1368                 error = locks_verify_locked(inode);
1369                 if (!error) {
1370                         DQUOT_INIT(inode);
1371                         
1372                         error = do_truncate(dentry, 0);
1373                 }
1374                 put_write_access(inode);
1375                 if (error)
1376                         return error;
1377         } else
1378                 if (flag & FMODE_WRITE)
1379                         DQUOT_INIT(inode);
1380
1381         return 0;
1382 }
1383
1384 /*
1385  *      open_namei()
1386  *
1387  * namei for open - this is in fact almost the whole open-routine.
1388  *
1389  * Note that the low bits of "flag" aren't the same as in the open
1390  * system call - they are 00 - no permissions needed
1391  *                        01 - read permission needed
1392  *                        10 - write permission needed
1393  *                        11 - read/write permissions needed
1394  * which is a lot more logical, and also allows the "no perm" needed
1395  * for symlinks (where the permissions are checked later).
1396  * SMP-safe
1397  */
1398 int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
1399 {
1400         int acc_mode, error = 0;
1401         struct dentry *dentry;
1402         struct dentry *dir;
1403         int count = 0;
1404
1405         acc_mode = ACC_MODE(flag);
1406
1407         /* Allow the LSM permission hook to distinguish append 
1408            access from general write access. */
1409         if (flag & O_APPEND)
1410                 acc_mode |= MAY_APPEND;
1411
1412         /* Fill in the open() intent data */
1413         nd->intent.open.flags = flag;
1414         nd->intent.open.create_mode = mode;
1415
1416         /*
1417          * The simplest case - just a plain lookup.
1418          */
1419         if (!(flag & O_CREAT)) {
1420                 error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd);
1421                 if (error)
1422                         return error;
1423                 goto ok;
1424         }
1425
1426         /*
1427          * Create - we need to know the parent.
1428          */
1429         error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd);
1430         if (error)
1431                 return error;
1432
1433         /*
1434          * We have the parent and last component. First of all, check
1435          * that we are not asked to creat(2) an obvious directory - that
1436          * will not do.
1437          */
1438         error = -EISDIR;
1439         if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
1440                 goto exit;
1441
1442         dir = nd->dentry;
1443         nd->flags &= ~LOOKUP_PARENT;
1444         down(&dir->d_inode->i_sem);
1445         dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1446
1447 do_last:
1448         error = PTR_ERR(dentry);
1449         if (IS_ERR(dentry)) {
1450                 up(&dir->d_inode->i_sem);
1451                 goto exit;
1452         }
1453
1454         /* Negative dentry, just create the file */
1455         if (!dentry->d_inode) {
1456                 if (!IS_POSIXACL(dir->d_inode))
1457                         mode &= ~current->fs->umask;
1458                 error = vfs_create(dir->d_inode, dentry, mode, nd);
1459                 up(&dir->d_inode->i_sem);
1460                 dput(nd->dentry);
1461                 nd->dentry = dentry;
1462                 if (error)
1463                         goto exit;
1464                 /* Don't check for write permission, don't truncate */
1465                 acc_mode = 0;
1466                 flag &= ~O_TRUNC;
1467                 goto ok;
1468         }
1469
1470         /*
1471          * It already exists.
1472          */
1473         up(&dir->d_inode->i_sem);
1474
1475         error = -EEXIST;
1476         if (flag & O_EXCL)
1477                 goto exit_dput;
1478
1479         if (d_mountpoint(dentry)) {
1480                 error = -ELOOP;
1481                 if (flag & O_NOFOLLOW)
1482                         goto exit_dput;
1483                 while (__follow_down(&nd->mnt,&dentry) && d_mountpoint(dentry));
1484         }
1485         error = -ENOENT;
1486         if (!dentry->d_inode)
1487                 goto exit_dput;
1488         if (dentry->d_inode->i_op && dentry->d_inode->i_op->follow_link)
1489                 goto do_link;
1490
1491         dput(nd->dentry);
1492         nd->dentry = dentry;
1493         error = -EISDIR;
1494         if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode))
1495                 goto exit;
1496 ok:
1497         error = may_open(nd, acc_mode, flag);
1498         if (error)
1499                 goto exit;
1500         return 0;
1501
1502 exit_dput:
1503         dput(dentry);
1504 exit:
1505         path_release(nd);
1506         return error;
1507
1508 do_link:
1509         error = -ELOOP;
1510         if (flag & O_NOFOLLOW)
1511                 goto exit_dput;
1512         /*
1513          * This is subtle. Instead of calling do_follow_link() we do the
1514          * thing by hands. The reason is that this way we have zero link_count
1515          * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1516          * After that we have the parent and last component, i.e.
1517          * we are in the same situation as after the first path_walk().
1518          * Well, almost - if the last component is normal we get its copy
1519          * stored in nd->last.name and we will have to putname() it when we
1520          * are done. Procfs-like symlinks just set LAST_BIND.
1521          */
1522         nd->flags |= LOOKUP_PARENT;
1523         error = security_inode_follow_link(dentry, nd);
1524         if (error)
1525                 goto exit_dput;
1526         error = __do_follow_link(dentry, nd);
1527         dput(dentry);
1528         if (error)
1529                 return error;
1530         nd->flags &= ~LOOKUP_PARENT;
1531         if (nd->last_type == LAST_BIND) {
1532                 dentry = nd->dentry;
1533                 goto ok;
1534         }
1535         error = -EISDIR;
1536         if (nd->last_type != LAST_NORM)
1537                 goto exit;
1538         if (nd->last.name[nd->last.len]) {
1539                 putname(nd->last.name);
1540                 goto exit;
1541         }
1542         error = -ELOOP;
1543         if (count++==32) {
1544                 putname(nd->last.name);
1545                 goto exit;
1546         }
1547         dir = nd->dentry;
1548         down(&dir->d_inode->i_sem);
1549         dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1550         putname(nd->last.name);
1551         goto do_last;
1552 }
1553
1554 /**
1555  * lookup_create - lookup a dentry, creating it if it doesn't exist
1556  * @nd: nameidata info
1557  * @is_dir: directory flag
1558  *
1559  * Simple function to lookup and return a dentry and create it
1560  * if it doesn't exist.  Is SMP-safe.
1561  */
1562 struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1563 {
1564         struct dentry *dentry;
1565
1566         down(&nd->dentry->d_inode->i_sem);
1567         dentry = ERR_PTR(-EEXIST);
1568         if (nd->last_type != LAST_NORM)
1569                 goto fail;
1570         nd->flags &= ~LOOKUP_PARENT;
1571         dentry = lookup_hash(&nd->last, nd->dentry);
1572         if (IS_ERR(dentry))
1573                 goto fail;
1574         if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
1575                 goto enoent;
1576         return dentry;
1577 enoent:
1578         dput(dentry);
1579         dentry = ERR_PTR(-ENOENT);
1580 fail:
1581         return dentry;
1582 }
1583
1584 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1585 {
1586         int error = may_create(dir, dentry, NULL);
1587
1588         if (error)
1589                 return error;
1590
1591         if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1592                 return -EPERM;
1593
1594         if (!dir->i_op || !dir->i_op->mknod)
1595                 return -EPERM;
1596
1597         error = security_inode_mknod(dir, dentry, mode, dev);
1598         if (error)
1599                 return error;
1600
1601         DQUOT_INIT(dir);
1602         error = dir->i_op->mknod(dir, dentry, mode, dev);
1603         if (!error) {
1604                 inode_dir_notify(dir, DN_CREATE);
1605                 security_inode_post_mknod(dir, dentry, mode, dev);
1606         }
1607         return error;
1608 }
1609
1610 asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev)
1611 {
1612         int error = 0;
1613         char * tmp;
1614         struct dentry * dentry;
1615         struct nameidata nd;
1616
1617         if (S_ISDIR(mode))
1618                 return -EPERM;
1619         tmp = getname(filename);
1620         if (IS_ERR(tmp))
1621                 return PTR_ERR(tmp);
1622
1623         error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1624         if (error)
1625                 goto out;
1626         dentry = lookup_create(&nd, 0);
1627         error = PTR_ERR(dentry);
1628
1629         if (!IS_POSIXACL(nd.dentry->d_inode))
1630                 mode &= ~current->fs->umask;
1631         if (!IS_ERR(dentry)) {
1632                 switch (mode & S_IFMT) {
1633                 case 0: case S_IFREG:
1634                         error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
1635                         break;
1636                 case S_IFCHR: case S_IFBLK:
1637                         error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
1638                                         new_decode_dev(dev));
1639                         break;
1640                 case S_IFIFO: case S_IFSOCK:
1641                         error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
1642                         break;
1643                 case S_IFDIR:
1644                         error = -EPERM;
1645                         break;
1646                 default:
1647                         error = -EINVAL;
1648                 }
1649                 dput(dentry);
1650         }
1651         up(&nd.dentry->d_inode->i_sem);
1652         path_release(&nd);
1653 out:
1654         putname(tmp);
1655
1656         return error;
1657 }
1658
1659 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1660 {
1661         int error = may_create(dir, dentry, NULL);
1662
1663         if (error)
1664                 return error;
1665
1666         if (!dir->i_op || !dir->i_op->mkdir)
1667                 return -EPERM;
1668
1669         mode &= (S_IRWXUGO|S_ISVTX);
1670         error = security_inode_mkdir(dir, dentry, mode);
1671         if (error)
1672                 return error;
1673
1674         DQUOT_INIT(dir);
1675         error = dir->i_op->mkdir(dir, dentry, mode);
1676         if (!error) {
1677                 inode_dir_notify(dir, DN_CREATE);
1678                 security_inode_post_mkdir(dir,dentry, mode);
1679         }
1680         return error;
1681 }
1682
1683 asmlinkage long sys_mkdir(const char __user * pathname, int mode)
1684 {
1685         int error = 0;
1686         char * tmp;
1687
1688         tmp = getname(pathname);
1689         error = PTR_ERR(tmp);
1690         if (!IS_ERR(tmp)) {
1691                 struct dentry *dentry;
1692                 struct nameidata nd;
1693
1694                 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1695                 if (error)
1696                         goto out;
1697                 dentry = lookup_create(&nd, 1);
1698                 error = PTR_ERR(dentry);
1699                 if (!IS_ERR(dentry)) {
1700                         if (!IS_POSIXACL(nd.dentry->d_inode))
1701                                 mode &= ~current->fs->umask;
1702                         error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
1703                         dput(dentry);
1704                 }
1705                 up(&nd.dentry->d_inode->i_sem);
1706                 path_release(&nd);
1707 out:
1708                 putname(tmp);
1709         }
1710
1711         return error;
1712 }
1713
1714 /*
1715  * We try to drop the dentry early: we should have
1716  * a usage count of 2 if we're the only user of this
1717  * dentry, and if that is true (possibly after pruning
1718  * the dcache), then we drop the dentry now.
1719  *
1720  * A low-level filesystem can, if it choses, legally
1721  * do a
1722  *
1723  *      if (!d_unhashed(dentry))
1724  *              return -EBUSY;
1725  *
1726  * if it cannot handle the case of removing a directory
1727  * that is still in use by something else..
1728  */
1729 void dentry_unhash(struct dentry *dentry)
1730 {
1731         dget(dentry);
1732         if (atomic_read(&dentry->d_count))
1733                 shrink_dcache_parent(dentry);
1734         spin_lock(&dcache_lock);
1735         spin_lock(&dentry->d_lock);
1736         if (atomic_read(&dentry->d_count) == 2)
1737                 __d_drop(dentry);
1738         spin_unlock(&dentry->d_lock);
1739         spin_unlock(&dcache_lock);
1740 }
1741
1742 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
1743 {
1744         int error = may_delete(dir, dentry, 1);
1745
1746         if (error)
1747                 return error;
1748
1749         if (!dir->i_op || !dir->i_op->rmdir)
1750                 return -EPERM;
1751
1752         DQUOT_INIT(dir);
1753
1754         down(&dentry->d_inode->i_sem);
1755         dentry_unhash(dentry);
1756         if (d_mountpoint(dentry))
1757                 error = -EBUSY;
1758         else {
1759                 error = security_inode_rmdir(dir, dentry);
1760                 if (!error) {
1761                         error = dir->i_op->rmdir(dir, dentry);
1762                         if (!error)
1763                                 dentry->d_inode->i_flags |= S_DEAD;
1764                 }
1765         }
1766         up(&dentry->d_inode->i_sem);
1767         if (!error) {
1768                 inode_dir_notify(dir, DN_DELETE);
1769                 d_delete(dentry);
1770         }
1771         dput(dentry);
1772
1773         return error;
1774 }
1775
1776 asmlinkage long sys_rmdir(const char __user * pathname)
1777 {
1778         int error = 0;
1779         char * name;
1780         struct dentry *dentry;
1781         struct nameidata nd;
1782
1783         name = getname(pathname);
1784         if(IS_ERR(name))
1785                 return PTR_ERR(name);
1786
1787         error = path_lookup(name, LOOKUP_PARENT, &nd);
1788         if (error)
1789                 goto exit;
1790
1791         switch(nd.last_type) {
1792                 case LAST_DOTDOT:
1793                         error = -ENOTEMPTY;
1794                         goto exit1;
1795                 case LAST_DOT:
1796                         error = -EINVAL;
1797                         goto exit1;
1798                 case LAST_ROOT:
1799                         error = -EBUSY;
1800                         goto exit1;
1801         }
1802         down(&nd.dentry->d_inode->i_sem);
1803         dentry = lookup_hash(&nd.last, nd.dentry);
1804         error = PTR_ERR(dentry);
1805         if (!IS_ERR(dentry)) {
1806                 error = vfs_rmdir(nd.dentry->d_inode, dentry);
1807                 dput(dentry);
1808         }
1809         up(&nd.dentry->d_inode->i_sem);
1810 exit1:
1811         path_release(&nd);
1812 exit:
1813         putname(name);
1814         return error;
1815 }
1816
1817 int vfs_unlink(struct inode *dir, struct dentry *dentry)
1818 {
1819         int error = may_delete(dir, dentry, 0);
1820
1821         if (error)
1822                 return error;
1823
1824         if (!dir->i_op || !dir->i_op->unlink)
1825                 return -EPERM;
1826
1827         DQUOT_INIT(dir);
1828
1829         down(&dentry->d_inode->i_sem);
1830         if (d_mountpoint(dentry))
1831                 error = -EBUSY;
1832         else {
1833                 error = security_inode_unlink(dir, dentry);
1834                 if (!error)
1835                         error = dir->i_op->unlink(dir, dentry);
1836         }
1837         up(&dentry->d_inode->i_sem);
1838
1839         /* We don't d_delete() NFS sillyrenamed files--they still exist. */
1840         if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
1841                 d_delete(dentry);
1842                 inode_dir_notify(dir, DN_DELETE);
1843         }
1844         return error;
1845 }
1846
1847 /*
1848  * Make sure that the actual truncation of the file will occur outside its
1849  * directory's i_sem.  Truncate can take a long time if there is a lot of
1850  * writeout happening, and we don't want to prevent access to the directory
1851  * while waiting on the I/O.
1852  */
1853 asmlinkage long sys_unlink(const char __user * pathname)
1854 {
1855         int error = 0;
1856         char * name;
1857         struct dentry *dentry;
1858         struct nameidata nd;
1859         struct inode *inode = NULL;
1860
1861         name = getname(pathname);
1862         if(IS_ERR(name))
1863                 return PTR_ERR(name);
1864
1865         error = path_lookup(name, LOOKUP_PARENT, &nd);
1866         if (error)
1867                 goto exit;
1868         error = -EISDIR;
1869         if (nd.last_type != LAST_NORM)
1870                 goto exit1;
1871         down(&nd.dentry->d_inode->i_sem);
1872         dentry = lookup_hash(&nd.last, nd.dentry);
1873         error = PTR_ERR(dentry);
1874         if (!IS_ERR(dentry)) {
1875                 /* Why not before? Because we want correct error value */
1876                 if (nd.last.name[nd.last.len])
1877                         goto slashes;
1878                 inode = dentry->d_inode;
1879                 if (inode)
1880                         atomic_inc(&inode->i_count);
1881                 error = vfs_unlink(nd.dentry->d_inode, dentry);
1882         exit2:
1883                 dput(dentry);
1884         }
1885         up(&nd.dentry->d_inode->i_sem);
1886         if (inode)
1887                 iput(inode);    /* truncate the inode here */
1888 exit1:
1889         path_release(&nd);
1890 exit:
1891         putname(name);
1892         return error;
1893
1894 slashes:
1895         error = !dentry->d_inode ? -ENOENT :
1896                 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
1897         goto exit2;
1898 }
1899
1900 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
1901 {
1902         int error = may_create(dir, dentry, NULL);
1903
1904         if (error)
1905                 return error;
1906
1907         if (!dir->i_op || !dir->i_op->symlink)
1908                 return -EPERM;
1909
1910         error = security_inode_symlink(dir, dentry, oldname);
1911         if (error)
1912                 return error;
1913
1914         DQUOT_INIT(dir);
1915         error = dir->i_op->symlink(dir, dentry, oldname);
1916         if (!error) {
1917                 inode_dir_notify(dir, DN_CREATE);
1918                 security_inode_post_symlink(dir, dentry, oldname);
1919         }
1920         return error;
1921 }
1922
1923 asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname)
1924 {
1925         int error = 0;
1926         char * from;
1927         char * to;
1928
1929         from = getname(oldname);
1930         if(IS_ERR(from))
1931                 return PTR_ERR(from);
1932         to = getname(newname);
1933         error = PTR_ERR(to);
1934         if (!IS_ERR(to)) {
1935                 struct dentry *dentry;
1936                 struct nameidata nd;
1937
1938                 error = path_lookup(to, LOOKUP_PARENT, &nd);
1939                 if (error)
1940                         goto out;
1941                 dentry = lookup_create(&nd, 0);
1942                 error = PTR_ERR(dentry);
1943                 if (!IS_ERR(dentry)) {
1944                         error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
1945                         dput(dentry);
1946                 }
1947                 up(&nd.dentry->d_inode->i_sem);
1948                 path_release(&nd);
1949 out:
1950                 putname(to);
1951         }
1952         putname(from);
1953         return error;
1954 }
1955
1956 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
1957 {
1958         struct inode *inode = old_dentry->d_inode;
1959         int error;
1960
1961         if (!inode)
1962                 return -ENOENT;
1963
1964         error = may_create(dir, new_dentry, NULL);
1965         if (error)
1966                 return error;
1967
1968         if (dir->i_sb != inode->i_sb)
1969                 return -EXDEV;
1970
1971         /*
1972          * A link to an append-only or immutable file cannot be created.
1973          */
1974         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1975                 return -EPERM;
1976         if (!dir->i_op || !dir->i_op->link)
1977                 return -EPERM;
1978         if (S_ISDIR(old_dentry->d_inode->i_mode))
1979                 return -EPERM;
1980
1981         error = security_inode_link(old_dentry, dir, new_dentry);
1982         if (error)
1983                 return error;
1984
1985         down(&old_dentry->d_inode->i_sem);
1986         DQUOT_INIT(dir);
1987         error = dir->i_op->link(old_dentry, dir, new_dentry);
1988         up(&old_dentry->d_inode->i_sem);
1989         if (!error) {
1990                 inode_dir_notify(dir, DN_CREATE);
1991                 security_inode_post_link(old_dentry, dir, new_dentry);
1992         }
1993         return error;
1994 }
1995
1996 /*
1997  * Hardlinks are often used in delicate situations.  We avoid
1998  * security-related surprises by not following symlinks on the
1999  * newname.  --KAB
2000  *
2001  * We don't follow them on the oldname either to be compatible
2002  * with linux 2.0, and to avoid hard-linking to directories
2003  * and other special files.  --ADM
2004  */
2005 asmlinkage long sys_link(const char __user * oldname, const char __user * newname)
2006 {
2007         struct dentry *new_dentry;
2008         struct nameidata nd, old_nd;
2009         int error;
2010         char * to;
2011
2012         to = getname(newname);
2013         if (IS_ERR(to))
2014                 return PTR_ERR(to);
2015
2016         error = __user_walk(oldname, 0, &old_nd);
2017         if (error)
2018                 goto exit;
2019         error = path_lookup(to, LOOKUP_PARENT, &nd);
2020         if (error)
2021                 goto out;
2022         error = -EXDEV;
2023         if (old_nd.mnt != nd.mnt)
2024                 goto out_release;
2025         new_dentry = lookup_create(&nd, 0);
2026         error = PTR_ERR(new_dentry);
2027         if (!IS_ERR(new_dentry)) {
2028                 error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
2029                 dput(new_dentry);
2030         }
2031         up(&nd.dentry->d_inode->i_sem);
2032 out_release:
2033         path_release(&nd);
2034 out:
2035         path_release(&old_nd);
2036 exit:
2037         putname(to);
2038
2039         return error;
2040 }
2041
2042 /*
2043  * The worst of all namespace operations - renaming directory. "Perverted"
2044  * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2045  * Problems:
2046  *      a) we can get into loop creation. Check is done in is_subdir().
2047  *      b) race potential - two innocent renames can create a loop together.
2048  *         That's where 4.4 screws up. Current fix: serialization on
2049  *         sb->s_vfs_rename_sem. We might be more accurate, but that's another
2050  *         story.
2051  *      c) we have to lock _three_ objects - parents and victim (if it exists).
2052  *         And that - after we got ->i_sem on parents (until then we don't know
2053  *         whether the target exists).  Solution: try to be smart with locking
2054  *         order for inodes.  We rely on the fact that tree topology may change
2055  *         only under ->s_vfs_rename_sem _and_ that parent of the object we
2056  *         move will be locked.  Thus we can rank directories by the tree
2057  *         (ancestors first) and rank all non-directories after them.
2058  *         That works since everybody except rename does "lock parent, lookup,
2059  *         lock child" and rename is under ->s_vfs_rename_sem.
2060  *         HOWEVER, it relies on the assumption that any object with ->lookup()
2061  *         has no more than 1 dentry.  If "hybrid" objects will ever appear,
2062  *         we'd better make sure that there's no link(2) for them.
2063  *      d) some filesystems don't support opened-but-unlinked directories,
2064  *         either because of layout or because they are not ready to deal with
2065  *         all cases correctly. The latter will be fixed (taking this sort of
2066  *         stuff into VFS), but the former is not going away. Solution: the same
2067  *         trick as in rmdir().
2068  *      e) conversion from fhandle to dentry may come in the wrong moment - when
2069  *         we are removing the target. Solution: we will have to grab ->i_sem
2070  *         in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2071  *         ->i_sem on parents, which works but leads to some truely excessive
2072  *         locking].
2073  */
2074 int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2075                struct inode *new_dir, struct dentry *new_dentry)
2076 {
2077         int error = 0;
2078         struct inode *target;
2079
2080         /*
2081          * If we are going to change the parent - check write permissions,
2082          * we'll need to flip '..'.
2083          */
2084         if (new_dir != old_dir) {
2085                 error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
2086                 if (error)
2087                         return error;
2088         }
2089
2090         error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2091         if (error)
2092                 return error;
2093
2094         target = new_dentry->d_inode;
2095         if (target) {
2096                 down(&target->i_sem);
2097                 dentry_unhash(new_dentry);
2098         }
2099         if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2100                 error = -EBUSY;
2101         else 
2102                 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2103         if (target) {
2104                 if (!error)
2105                         target->i_flags |= S_DEAD;
2106                 up(&target->i_sem);
2107                 if (d_unhashed(new_dentry))
2108                         d_rehash(new_dentry);
2109                 dput(new_dentry);
2110         }
2111         if (!error) {
2112                 d_move(old_dentry,new_dentry);
2113                 security_inode_post_rename(old_dir, old_dentry,
2114                                            new_dir, new_dentry);
2115         }
2116         return error;
2117 }
2118
2119 int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2120                struct inode *new_dir, struct dentry *new_dentry)
2121 {
2122         struct inode *target;
2123         int error;
2124
2125         error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2126         if (error)
2127                 return error;
2128
2129         dget(new_dentry);
2130         target = new_dentry->d_inode;
2131         if (target)
2132                 down(&target->i_sem);
2133         if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2134                 error = -EBUSY;
2135         else
2136                 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2137         if (!error) {
2138                 /* The following d_move() should become unconditional */
2139                 if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME))
2140                         d_move(old_dentry, new_dentry);
2141                 security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry);
2142         }
2143         if (target)
2144                 up(&target->i_sem);
2145         dput(new_dentry);
2146         return error;
2147 }
2148
2149 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2150                struct inode *new_dir, struct dentry *new_dentry)
2151 {
2152         int error;
2153         int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2154
2155         if (old_dentry->d_inode == new_dentry->d_inode)
2156                 return 0;
2157  
2158         error = may_delete(old_dir, old_dentry, is_dir);
2159         if (error)
2160                 return error;
2161
2162         if (!new_dentry->d_inode)
2163                 error = may_create(new_dir, new_dentry, NULL);
2164         else
2165                 error = may_delete(new_dir, new_dentry, is_dir);
2166         if (error)
2167                 return error;
2168
2169         if (!old_dir->i_op || !old_dir->i_op->rename)
2170                 return -EPERM;
2171
2172         DQUOT_INIT(old_dir);
2173         DQUOT_INIT(new_dir);
2174
2175         if (is_dir)
2176                 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2177         else
2178                 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2179         if (!error) {
2180                 if (old_dir == new_dir)
2181                         inode_dir_notify(old_dir, DN_RENAME);
2182                 else {
2183                         inode_dir_notify(old_dir, DN_DELETE);
2184                         inode_dir_notify(new_dir, DN_CREATE);
2185                 }
2186         }
2187         return error;
2188 }
2189
2190 static inline int do_rename(const char * oldname, const char * newname)
2191 {
2192         int error = 0;
2193         struct dentry * old_dir, * new_dir;
2194         struct dentry * old_dentry, *new_dentry;
2195         struct dentry * trap;
2196         struct nameidata oldnd, newnd;
2197
2198         error = path_lookup(oldname, LOOKUP_PARENT, &oldnd);
2199         if (error)
2200                 goto exit;
2201
2202         error = path_lookup(newname, LOOKUP_PARENT, &newnd);
2203         if (error)
2204                 goto exit1;
2205
2206         error = -EXDEV;
2207         if (oldnd.mnt != newnd.mnt)
2208                 goto exit2;
2209
2210         old_dir = oldnd.dentry;
2211         error = -EBUSY;
2212         if (oldnd.last_type != LAST_NORM)
2213                 goto exit2;
2214
2215         new_dir = newnd.dentry;
2216         if (newnd.last_type != LAST_NORM)
2217                 goto exit2;
2218
2219         trap = lock_rename(new_dir, old_dir);
2220
2221         old_dentry = lookup_hash(&oldnd.last, old_dir);
2222         error = PTR_ERR(old_dentry);
2223         if (IS_ERR(old_dentry))
2224                 goto exit3;
2225         /* source must exist */
2226         error = -ENOENT;
2227         if (!old_dentry->d_inode)
2228                 goto exit4;
2229         /* unless the source is a directory trailing slashes give -ENOTDIR */
2230         if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2231                 error = -ENOTDIR;
2232                 if (oldnd.last.name[oldnd.last.len])
2233                         goto exit4;
2234                 if (newnd.last.name[newnd.last.len])
2235                         goto exit4;
2236         }
2237         /* source should not be ancestor of target */
2238         error = -EINVAL;
2239         if (old_dentry == trap)
2240                 goto exit4;
2241         new_dentry = lookup_hash(&newnd.last, new_dir);
2242         error = PTR_ERR(new_dentry);
2243         if (IS_ERR(new_dentry))
2244                 goto exit4;
2245         /* target should not be an ancestor of source */
2246         error = -ENOTEMPTY;
2247         if (new_dentry == trap)
2248                 goto exit5;
2249
2250         error = vfs_rename(old_dir->d_inode, old_dentry,
2251                                    new_dir->d_inode, new_dentry);
2252 exit5:
2253         dput(new_dentry);
2254 exit4:
2255         dput(old_dentry);
2256 exit3:
2257         unlock_rename(new_dir, old_dir);
2258 exit2:
2259         path_release(&newnd);
2260 exit1:
2261         path_release(&oldnd);
2262 exit:
2263         return error;
2264 }
2265
2266 asmlinkage long sys_rename(const char __user * oldname, const char __user * newname)
2267 {
2268         int error;
2269         char * from;
2270         char * to;
2271
2272         from = getname(oldname);
2273         if(IS_ERR(from))
2274                 return PTR_ERR(from);
2275         to = getname(newname);
2276         error = PTR_ERR(to);
2277         if (!IS_ERR(to)) {
2278                 error = do_rename(from,to);
2279                 putname(to);
2280         }
2281         putname(from);
2282         return error;
2283 }
2284
2285 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2286 {
2287         int len;
2288
2289         len = PTR_ERR(link);
2290         if (IS_ERR(link))
2291                 goto out;
2292
2293         len = strlen(link);
2294         if (len > (unsigned) buflen)
2295                 len = buflen;
2296         if (copy_to_user(buffer, link, len))
2297                 len = -EFAULT;
2298 out:
2299         return len;
2300 }
2301
2302 /*
2303  * A helper for ->readlink().  This should be used *ONLY* for symlinks that
2304  * have ->follow_link() touching nd only in nd_set_link().  Using (or not
2305  * using) it for any given inode is up to filesystem.
2306  */
2307 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2308 {
2309         struct nameidata nd;
2310         int res;
2311         nd.depth = 0;
2312         res = dentry->d_inode->i_op->follow_link(dentry, &nd);
2313         if (!res) {
2314                 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2315                 if (dentry->d_inode->i_op->put_link)
2316                         dentry->d_inode->i_op->put_link(dentry, &nd);
2317         }
2318         return res;
2319 }
2320
2321 int vfs_follow_link(struct nameidata *nd, const char *link)
2322 {
2323         return __vfs_follow_link(nd, link);
2324 }
2325
2326 /* get the link contents into pagecache */
2327 static char *page_getlink(struct dentry * dentry, struct page **ppage)
2328 {
2329         struct page * page;
2330         struct address_space *mapping = dentry->d_inode->i_mapping;
2331         page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
2332                                 NULL);
2333         if (IS_ERR(page))
2334                 goto sync_fail;
2335         wait_on_page_locked(page);
2336         if (!PageUptodate(page))
2337                 goto async_fail;
2338         *ppage = page;
2339         return kmap(page);
2340
2341 async_fail:
2342         page_cache_release(page);
2343         return ERR_PTR(-EIO);
2344
2345 sync_fail:
2346         return (char*)page;
2347 }
2348
2349 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2350 {
2351         struct page *page = NULL;
2352         char *s = page_getlink(dentry, &page);
2353         int res = vfs_readlink(dentry,buffer,buflen,s);
2354         if (page) {
2355                 kunmap(page);
2356                 page_cache_release(page);
2357         }
2358         return res;
2359 }
2360
2361 int page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
2362 {
2363         struct page *page;
2364         nd_set_link(nd, page_getlink(dentry, &page));
2365         return 0;
2366 }
2367
2368 void page_put_link(struct dentry *dentry, struct nameidata *nd)
2369 {
2370         if (!IS_ERR(nd_get_link(nd))) {
2371                 struct page *page;
2372                 page = find_get_page(dentry->d_inode->i_mapping, 0);
2373                 if (!page)
2374                         BUG();
2375                 kunmap(page);
2376                 page_cache_release(page);
2377                 page_cache_release(page);
2378         }
2379 }
2380
2381 int page_symlink(struct inode *inode, const char *symname, int len)
2382 {
2383         struct address_space *mapping = inode->i_mapping;
2384         struct page *page = grab_cache_page(mapping, 0);
2385         int err = -ENOMEM;
2386         char *kaddr;
2387
2388         if (!page)
2389                 goto fail;
2390         err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
2391         if (err)
2392                 goto fail_map;
2393         kaddr = kmap_atomic(page, KM_USER0);
2394         memcpy(kaddr, symname, len-1);
2395         kunmap_atomic(kaddr, KM_USER0);
2396         mapping->a_ops->commit_write(NULL, page, 0, len-1);
2397         /*
2398          * Notice that we are _not_ going to block here - end of page is
2399          * unmapped, so this will only try to map the rest of page, see
2400          * that it is unmapped (typically even will not look into inode -
2401          * ->i_size will be enough for everything) and zero it out.
2402          * OTOH it's obviously correct and should make the page up-to-date.
2403          */
2404         if (!PageUptodate(page)) {
2405                 err = mapping->a_ops->readpage(NULL, page);
2406                 wait_on_page_locked(page);
2407         } else {
2408                 unlock_page(page);
2409         }
2410         page_cache_release(page);
2411         if (err < 0)
2412                 goto fail;
2413         mark_inode_dirty(inode);
2414         return 0;
2415 fail_map:
2416         unlock_page(page);
2417         page_cache_release(page);
2418 fail:
2419         return err;
2420 }
2421
2422 struct inode_operations page_symlink_inode_operations = {
2423         .readlink       = generic_readlink,
2424         .follow_link    = page_follow_link_light,
2425         .put_link       = page_put_link,
2426 };
2427
2428 EXPORT_SYMBOL(__user_walk);
2429 EXPORT_SYMBOL(follow_down);
2430 EXPORT_SYMBOL(follow_up);
2431 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2432 EXPORT_SYMBOL(getname);
2433 EXPORT_SYMBOL(lock_rename);
2434 EXPORT_SYMBOL(lookup_hash);
2435 EXPORT_SYMBOL(lookup_one_len);
2436 EXPORT_SYMBOL(page_follow_link_light);
2437 EXPORT_SYMBOL(page_put_link);
2438 EXPORT_SYMBOL(page_readlink);
2439 EXPORT_SYMBOL(page_symlink);
2440 EXPORT_SYMBOL(page_symlink_inode_operations);
2441 EXPORT_SYMBOL(path_lookup);
2442 EXPORT_SYMBOL(path_release);
2443 EXPORT_SYMBOL(path_walk);
2444 EXPORT_SYMBOL(permission);
2445 EXPORT_SYMBOL(unlock_rename);
2446 EXPORT_SYMBOL(vfs_create);
2447 EXPORT_SYMBOL(vfs_follow_link);
2448 EXPORT_SYMBOL(vfs_link);
2449 EXPORT_SYMBOL(vfs_mkdir);
2450 EXPORT_SYMBOL(vfs_mknod);
2451 EXPORT_SYMBOL(generic_permission);
2452 EXPORT_SYMBOL(vfs_readlink);
2453 EXPORT_SYMBOL(vfs_rename);
2454 EXPORT_SYMBOL(vfs_rmdir);
2455 EXPORT_SYMBOL(vfs_symlink);
2456 EXPORT_SYMBOL(vfs_unlink);
2457 EXPORT_SYMBOL(dentry_unhash);
2458 EXPORT_SYMBOL(generic_readlink);