[PATCH] inotify
[linux-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/fsnotify.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_no_expire(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 struct path {
497         struct vfsmount *mnt;
498         struct dentry *dentry;
499 };
500
501 static inline int __do_follow_link(struct path *path, struct nameidata *nd)
502 {
503         int error;
504         struct dentry *dentry = path->dentry;
505
506         touch_atime(path->mnt, dentry);
507         nd_set_link(nd, NULL);
508
509         if (path->mnt == nd->mnt)
510                 mntget(path->mnt);
511         error = dentry->d_inode->i_op->follow_link(dentry, nd);
512         if (!error) {
513                 char *s = nd_get_link(nd);
514                 if (s)
515                         error = __vfs_follow_link(nd, s);
516                 if (dentry->d_inode->i_op->put_link)
517                         dentry->d_inode->i_op->put_link(dentry, nd);
518         }
519         dput(dentry);
520         mntput(path->mnt);
521
522         return error;
523 }
524
525 /*
526  * This limits recursive symlink follows to 8, while
527  * limiting consecutive symlinks to 40.
528  *
529  * Without that kind of total limit, nasty chains of consecutive
530  * symlinks can cause almost arbitrarily long lookups. 
531  */
532 static inline int do_follow_link(struct path *path, struct nameidata *nd)
533 {
534         int err = -ELOOP;
535         if (current->link_count >= MAX_NESTED_LINKS)
536                 goto loop;
537         if (current->total_link_count >= 40)
538                 goto loop;
539         BUG_ON(nd->depth >= MAX_NESTED_LINKS);
540         cond_resched();
541         err = security_inode_follow_link(path->dentry, nd);
542         if (err)
543                 goto loop;
544         current->link_count++;
545         current->total_link_count++;
546         nd->depth++;
547         err = __do_follow_link(path, nd);
548         current->link_count--;
549         nd->depth--;
550         return err;
551 loop:
552         dput(path->dentry);
553         if (path->mnt != nd->mnt)
554                 mntput(path->mnt);
555         path_release(nd);
556         return err;
557 }
558
559 int follow_up(struct vfsmount **mnt, struct dentry **dentry)
560 {
561         struct vfsmount *parent;
562         struct dentry *mountpoint;
563         spin_lock(&vfsmount_lock);
564         parent=(*mnt)->mnt_parent;
565         if (parent == *mnt) {
566                 spin_unlock(&vfsmount_lock);
567                 return 0;
568         }
569         mntget(parent);
570         mountpoint=dget((*mnt)->mnt_mountpoint);
571         spin_unlock(&vfsmount_lock);
572         dput(*dentry);
573         *dentry = mountpoint;
574         mntput(*mnt);
575         *mnt = parent;
576         return 1;
577 }
578
579 /* no need for dcache_lock, as serialization is taken care in
580  * namespace.c
581  */
582 static int __follow_mount(struct path *path)
583 {
584         int res = 0;
585         while (d_mountpoint(path->dentry)) {
586                 struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
587                 if (!mounted)
588                         break;
589                 dput(path->dentry);
590                 if (res)
591                         mntput(path->mnt);
592                 path->mnt = mounted;
593                 path->dentry = dget(mounted->mnt_root);
594                 res = 1;
595         }
596         return res;
597 }
598
599 static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
600 {
601         while (d_mountpoint(*dentry)) {
602                 struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
603                 if (!mounted)
604                         break;
605                 dput(*dentry);
606                 mntput(*mnt);
607                 *mnt = mounted;
608                 *dentry = dget(mounted->mnt_root);
609         }
610 }
611
612 /* no need for dcache_lock, as serialization is taken care in
613  * namespace.c
614  */
615 int follow_down(struct vfsmount **mnt, struct dentry **dentry)
616 {
617         struct vfsmount *mounted;
618
619         mounted = lookup_mnt(*mnt, *dentry);
620         if (mounted) {
621                 dput(*dentry);
622                 mntput(*mnt);
623                 *mnt = mounted;
624                 *dentry = dget(mounted->mnt_root);
625                 return 1;
626         }
627         return 0;
628 }
629
630 static inline void follow_dotdot(struct nameidata *nd)
631 {
632         while(1) {
633                 struct vfsmount *parent;
634                 struct dentry *old = nd->dentry;
635
636                 read_lock(&current->fs->lock);
637                 if (nd->dentry == current->fs->root &&
638                     nd->mnt == current->fs->rootmnt) {
639                         read_unlock(&current->fs->lock);
640                         break;
641                 }
642                 read_unlock(&current->fs->lock);
643                 spin_lock(&dcache_lock);
644                 if (nd->dentry != nd->mnt->mnt_root) {
645                         nd->dentry = dget(nd->dentry->d_parent);
646                         spin_unlock(&dcache_lock);
647                         dput(old);
648                         break;
649                 }
650                 spin_unlock(&dcache_lock);
651                 spin_lock(&vfsmount_lock);
652                 parent = nd->mnt->mnt_parent;
653                 if (parent == nd->mnt) {
654                         spin_unlock(&vfsmount_lock);
655                         break;
656                 }
657                 mntget(parent);
658                 nd->dentry = dget(nd->mnt->mnt_mountpoint);
659                 spin_unlock(&vfsmount_lock);
660                 dput(old);
661                 mntput(nd->mnt);
662                 nd->mnt = parent;
663         }
664         follow_mount(&nd->mnt, &nd->dentry);
665 }
666
667 /*
668  *  It's more convoluted than I'd like it to be, but... it's still fairly
669  *  small and for now I'd prefer to have fast path as straight as possible.
670  *  It _is_ time-critical.
671  */
672 static int do_lookup(struct nameidata *nd, struct qstr *name,
673                      struct path *path)
674 {
675         struct vfsmount *mnt = nd->mnt;
676         struct dentry *dentry = __d_lookup(nd->dentry, name);
677
678         if (!dentry)
679                 goto need_lookup;
680         if (dentry->d_op && dentry->d_op->d_revalidate)
681                 goto need_revalidate;
682 done:
683         path->mnt = mnt;
684         path->dentry = dentry;
685         __follow_mount(path);
686         return 0;
687
688 need_lookup:
689         dentry = real_lookup(nd->dentry, name, nd);
690         if (IS_ERR(dentry))
691                 goto fail;
692         goto done;
693
694 need_revalidate:
695         if (dentry->d_op->d_revalidate(dentry, nd))
696                 goto done;
697         if (d_invalidate(dentry))
698                 goto done;
699         dput(dentry);
700         goto need_lookup;
701
702 fail:
703         return PTR_ERR(dentry);
704 }
705
706 /*
707  * Name resolution.
708  * This is the basic name resolution function, turning a pathname into
709  * the final dentry. We expect 'base' to be positive and a directory.
710  *
711  * Returns 0 and nd will have valid dentry and mnt on success.
712  * Returns error and drops reference to input namei data on failure.
713  */
714 static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
715 {
716         struct path next;
717         struct inode *inode;
718         int err;
719         unsigned int lookup_flags = nd->flags;
720         
721         while (*name=='/')
722                 name++;
723         if (!*name)
724                 goto return_reval;
725
726         inode = nd->dentry->d_inode;
727         if (nd->depth)
728                 lookup_flags = LOOKUP_FOLLOW;
729
730         /* At this point we know we have a real path component. */
731         for(;;) {
732                 unsigned long hash;
733                 struct qstr this;
734                 unsigned int c;
735
736                 err = exec_permission_lite(inode, nd);
737                 if (err == -EAGAIN) { 
738                         err = permission(inode, MAY_EXEC, nd);
739                 }
740                 if (err)
741                         break;
742
743                 this.name = name;
744                 c = *(const unsigned char *)name;
745
746                 hash = init_name_hash();
747                 do {
748                         name++;
749                         hash = partial_name_hash(c, hash);
750                         c = *(const unsigned char *)name;
751                 } while (c && (c != '/'));
752                 this.len = name - (const char *) this.name;
753                 this.hash = end_name_hash(hash);
754
755                 /* remove trailing slashes? */
756                 if (!c)
757                         goto last_component;
758                 while (*++name == '/');
759                 if (!*name)
760                         goto last_with_slashes;
761
762                 /*
763                  * "." and ".." are special - ".." especially so because it has
764                  * to be able to know about the current root directory and
765                  * parent relationships.
766                  */
767                 if (this.name[0] == '.') switch (this.len) {
768                         default:
769                                 break;
770                         case 2: 
771                                 if (this.name[1] != '.')
772                                         break;
773                                 follow_dotdot(nd);
774                                 inode = nd->dentry->d_inode;
775                                 /* fallthrough */
776                         case 1:
777                                 continue;
778                 }
779                 /*
780                  * See if the low-level filesystem might want
781                  * to use its own hash..
782                  */
783                 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
784                         err = nd->dentry->d_op->d_hash(nd->dentry, &this);
785                         if (err < 0)
786                                 break;
787                 }
788                 nd->flags |= LOOKUP_CONTINUE;
789                 /* This does the actual lookups.. */
790                 err = do_lookup(nd, &this, &next);
791                 if (err)
792                         break;
793
794                 err = -ENOENT;
795                 inode = next.dentry->d_inode;
796                 if (!inode)
797                         goto out_dput;
798                 err = -ENOTDIR; 
799                 if (!inode->i_op)
800                         goto out_dput;
801
802                 if (inode->i_op->follow_link) {
803                         err = do_follow_link(&next, nd);
804                         if (err)
805                                 goto return_err;
806                         err = -ENOENT;
807                         inode = nd->dentry->d_inode;
808                         if (!inode)
809                                 break;
810                         err = -ENOTDIR; 
811                         if (!inode->i_op)
812                                 break;
813                 } else {
814                         dput(nd->dentry);
815                         if (nd->mnt != next.mnt)
816                                 mntput(nd->mnt);
817                         nd->mnt = next.mnt;
818                         nd->dentry = next.dentry;
819                 }
820                 err = -ENOTDIR; 
821                 if (!inode->i_op->lookup)
822                         break;
823                 continue;
824                 /* here ends the main loop */
825
826 last_with_slashes:
827                 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
828 last_component:
829                 nd->flags &= ~LOOKUP_CONTINUE;
830                 if (lookup_flags & LOOKUP_PARENT)
831                         goto lookup_parent;
832                 if (this.name[0] == '.') switch (this.len) {
833                         default:
834                                 break;
835                         case 2: 
836                                 if (this.name[1] != '.')
837                                         break;
838                                 follow_dotdot(nd);
839                                 inode = nd->dentry->d_inode;
840                                 /* fallthrough */
841                         case 1:
842                                 goto return_reval;
843                 }
844                 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
845                         err = nd->dentry->d_op->d_hash(nd->dentry, &this);
846                         if (err < 0)
847                                 break;
848                 }
849                 err = do_lookup(nd, &this, &next);
850                 if (err)
851                         break;
852                 inode = next.dentry->d_inode;
853                 if ((lookup_flags & LOOKUP_FOLLOW)
854                     && inode && inode->i_op && inode->i_op->follow_link) {
855                         err = do_follow_link(&next, nd);
856                         if (err)
857                                 goto return_err;
858                         inode = nd->dentry->d_inode;
859                 } else {
860                         dput(nd->dentry);
861                         if (nd->mnt != next.mnt)
862                                 mntput(nd->mnt);
863                         nd->mnt = next.mnt;
864                         nd->dentry = next.dentry;
865                 }
866                 err = -ENOENT;
867                 if (!inode)
868                         break;
869                 if (lookup_flags & LOOKUP_DIRECTORY) {
870                         err = -ENOTDIR; 
871                         if (!inode->i_op || !inode->i_op->lookup)
872                                 break;
873                 }
874                 goto return_base;
875 lookup_parent:
876                 nd->last = this;
877                 nd->last_type = LAST_NORM;
878                 if (this.name[0] != '.')
879                         goto return_base;
880                 if (this.len == 1)
881                         nd->last_type = LAST_DOT;
882                 else if (this.len == 2 && this.name[1] == '.')
883                         nd->last_type = LAST_DOTDOT;
884                 else
885                         goto return_base;
886 return_reval:
887                 /*
888                  * We bypassed the ordinary revalidation routines.
889                  * We may need to check the cached dentry for staleness.
890                  */
891                 if (nd->dentry && nd->dentry->d_sb &&
892                     (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
893                         err = -ESTALE;
894                         /* Note: we do not d_invalidate() */
895                         if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
896                                 break;
897                 }
898 return_base:
899                 return 0;
900 out_dput:
901                 dput(next.dentry);
902                 if (nd->mnt != next.mnt)
903                         mntput(next.mnt);
904                 break;
905         }
906         path_release(nd);
907 return_err:
908         return err;
909 }
910
911 /*
912  * Wrapper to retry pathname resolution whenever the underlying
913  * file system returns an ESTALE.
914  *
915  * Retry the whole path once, forcing real lookup requests
916  * instead of relying on the dcache.
917  */
918 int fastcall link_path_walk(const char *name, struct nameidata *nd)
919 {
920         struct nameidata save = *nd;
921         int result;
922
923         /* make sure the stuff we saved doesn't go away */
924         dget(save.dentry);
925         mntget(save.mnt);
926
927         result = __link_path_walk(name, nd);
928         if (result == -ESTALE) {
929                 *nd = save;
930                 dget(nd->dentry);
931                 mntget(nd->mnt);
932                 nd->flags |= LOOKUP_REVAL;
933                 result = __link_path_walk(name, nd);
934         }
935
936         dput(save.dentry);
937         mntput(save.mnt);
938
939         return result;
940 }
941
942 int fastcall path_walk(const char * name, struct nameidata *nd)
943 {
944         current->total_link_count = 0;
945         return link_path_walk(name, nd);
946 }
947
948 /* 
949  * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
950  * everything is done. Returns 0 and drops input nd, if lookup failed;
951  */
952 static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
953 {
954         if (path_walk(name, nd))
955                 return 0;               /* something went wrong... */
956
957         if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
958                 struct dentry *old_dentry = nd->dentry;
959                 struct vfsmount *old_mnt = nd->mnt;
960                 struct qstr last = nd->last;
961                 int last_type = nd->last_type;
962                 /*
963                  * NAME was not found in alternate root or it's a directory.  Try to find
964                  * it in the normal root:
965                  */
966                 nd->last_type = LAST_ROOT;
967                 read_lock(&current->fs->lock);
968                 nd->mnt = mntget(current->fs->rootmnt);
969                 nd->dentry = dget(current->fs->root);
970                 read_unlock(&current->fs->lock);
971                 if (path_walk(name, nd) == 0) {
972                         if (nd->dentry->d_inode) {
973                                 dput(old_dentry);
974                                 mntput(old_mnt);
975                                 return 1;
976                         }
977                         path_release(nd);
978                 }
979                 nd->dentry = old_dentry;
980                 nd->mnt = old_mnt;
981                 nd->last = last;
982                 nd->last_type = last_type;
983         }
984         return 1;
985 }
986
987 void set_fs_altroot(void)
988 {
989         char *emul = __emul_prefix();
990         struct nameidata nd;
991         struct vfsmount *mnt = NULL, *oldmnt;
992         struct dentry *dentry = NULL, *olddentry;
993         int err;
994
995         if (!emul)
996                 goto set_it;
997         err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
998         if (!err) {
999                 mnt = nd.mnt;
1000                 dentry = nd.dentry;
1001         }
1002 set_it:
1003         write_lock(&current->fs->lock);
1004         oldmnt = current->fs->altrootmnt;
1005         olddentry = current->fs->altroot;
1006         current->fs->altrootmnt = mnt;
1007         current->fs->altroot = dentry;
1008         write_unlock(&current->fs->lock);
1009         if (olddentry) {
1010                 dput(olddentry);
1011                 mntput(oldmnt);
1012         }
1013 }
1014
1015 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1016 int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd)
1017 {
1018         int retval = 0;
1019
1020         nd->last_type = LAST_ROOT; /* if there are only slashes... */
1021         nd->flags = flags;
1022         nd->depth = 0;
1023
1024         read_lock(&current->fs->lock);
1025         if (*name=='/') {
1026                 if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
1027                         nd->mnt = mntget(current->fs->altrootmnt);
1028                         nd->dentry = dget(current->fs->altroot);
1029                         read_unlock(&current->fs->lock);
1030                         if (__emul_lookup_dentry(name,nd))
1031                                 goto out; /* found in altroot */
1032                         read_lock(&current->fs->lock);
1033                 }
1034                 nd->mnt = mntget(current->fs->rootmnt);
1035                 nd->dentry = dget(current->fs->root);
1036         } else {
1037                 nd->mnt = mntget(current->fs->pwdmnt);
1038                 nd->dentry = dget(current->fs->pwd);
1039         }
1040         read_unlock(&current->fs->lock);
1041         current->total_link_count = 0;
1042         retval = link_path_walk(name, nd);
1043 out:
1044         if (unlikely(current->audit_context
1045                      && nd && nd->dentry && nd->dentry->d_inode))
1046                 audit_inode(name, nd->dentry->d_inode);
1047         return retval;
1048 }
1049
1050 /*
1051  * Restricted form of lookup. Doesn't follow links, single-component only,
1052  * needs parent already locked. Doesn't follow mounts.
1053  * SMP-safe.
1054  */
1055 static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
1056 {
1057         struct dentry * dentry;
1058         struct inode *inode;
1059         int err;
1060
1061         inode = base->d_inode;
1062         err = permission(inode, MAY_EXEC, nd);
1063         dentry = ERR_PTR(err);
1064         if (err)
1065                 goto out;
1066
1067         /*
1068          * See if the low-level filesystem might want
1069          * to use its own hash..
1070          */
1071         if (base->d_op && base->d_op->d_hash) {
1072                 err = base->d_op->d_hash(base, name);
1073                 dentry = ERR_PTR(err);
1074                 if (err < 0)
1075                         goto out;
1076         }
1077
1078         dentry = cached_lookup(base, name, nd);
1079         if (!dentry) {
1080                 struct dentry *new = d_alloc(base, name);
1081                 dentry = ERR_PTR(-ENOMEM);
1082                 if (!new)
1083                         goto out;
1084                 dentry = inode->i_op->lookup(inode, new, nd);
1085                 if (!dentry)
1086                         dentry = new;
1087                 else
1088                         dput(new);
1089         }
1090 out:
1091         return dentry;
1092 }
1093
1094 struct dentry * lookup_hash(struct qstr *name, struct dentry * base)
1095 {
1096         return __lookup_hash(name, base, NULL);
1097 }
1098
1099 /* SMP-safe */
1100 struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
1101 {
1102         unsigned long hash;
1103         struct qstr this;
1104         unsigned int c;
1105
1106         this.name = name;
1107         this.len = len;
1108         if (!len)
1109                 goto access;
1110
1111         hash = init_name_hash();
1112         while (len--) {
1113                 c = *(const unsigned char *)name++;
1114                 if (c == '/' || c == '\0')
1115                         goto access;
1116                 hash = partial_name_hash(c, hash);
1117         }
1118         this.hash = end_name_hash(hash);
1119
1120         return lookup_hash(&this, base);
1121 access:
1122         return ERR_PTR(-EACCES);
1123 }
1124
1125 /*
1126  *      namei()
1127  *
1128  * is used by most simple commands to get the inode of a specified name.
1129  * Open, link etc use their own routines, but this is enough for things
1130  * like 'chmod' etc.
1131  *
1132  * namei exists in two versions: namei/lnamei. The only difference is
1133  * that namei follows links, while lnamei does not.
1134  * SMP-safe
1135  */
1136 int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
1137 {
1138         char *tmp = getname(name);
1139         int err = PTR_ERR(tmp);
1140
1141         if (!IS_ERR(tmp)) {
1142                 err = path_lookup(tmp, flags, nd);
1143                 putname(tmp);
1144         }
1145         return err;
1146 }
1147
1148 /*
1149  * It's inline, so penalty for filesystems that don't use sticky bit is
1150  * minimal.
1151  */
1152 static inline int check_sticky(struct inode *dir, struct inode *inode)
1153 {
1154         if (!(dir->i_mode & S_ISVTX))
1155                 return 0;
1156         if (inode->i_uid == current->fsuid)
1157                 return 0;
1158         if (dir->i_uid == current->fsuid)
1159                 return 0;
1160         return !capable(CAP_FOWNER);
1161 }
1162
1163 /*
1164  *      Check whether we can remove a link victim from directory dir, check
1165  *  whether the type of victim is right.
1166  *  1. We can't do it if dir is read-only (done in permission())
1167  *  2. We should have write and exec permissions on dir
1168  *  3. We can't remove anything from append-only dir
1169  *  4. We can't do anything with immutable dir (done in permission())
1170  *  5. If the sticky bit on dir is set we should either
1171  *      a. be owner of dir, or
1172  *      b. be owner of victim, or
1173  *      c. have CAP_FOWNER capability
1174  *  6. If the victim is append-only or immutable we can't do antyhing with
1175  *     links pointing to it.
1176  *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1177  *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1178  *  9. We can't remove a root or mountpoint.
1179  * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1180  *     nfs_async_unlink().
1181  */
1182 static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1183 {
1184         int error;
1185
1186         if (!victim->d_inode)
1187                 return -ENOENT;
1188
1189         BUG_ON(victim->d_parent->d_inode != dir);
1190
1191         error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
1192         if (error)
1193                 return error;
1194         if (IS_APPEND(dir))
1195                 return -EPERM;
1196         if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1197             IS_IMMUTABLE(victim->d_inode))
1198                 return -EPERM;
1199         if (isdir) {
1200                 if (!S_ISDIR(victim->d_inode->i_mode))
1201                         return -ENOTDIR;
1202                 if (IS_ROOT(victim))
1203                         return -EBUSY;
1204         } else if (S_ISDIR(victim->d_inode->i_mode))
1205                 return -EISDIR;
1206         if (IS_DEADDIR(dir))
1207                 return -ENOENT;
1208         if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1209                 return -EBUSY;
1210         return 0;
1211 }
1212
1213 /*      Check whether we can create an object with dentry child in directory
1214  *  dir.
1215  *  1. We can't do it if child already exists (open has special treatment for
1216  *     this case, but since we are inlined it's OK)
1217  *  2. We can't do it if dir is read-only (done in permission())
1218  *  3. We should have write and exec permissions on dir
1219  *  4. We can't do it if dir is immutable (done in permission())
1220  */
1221 static inline int may_create(struct inode *dir, struct dentry *child,
1222                              struct nameidata *nd)
1223 {
1224         if (child->d_inode)
1225                 return -EEXIST;
1226         if (IS_DEADDIR(dir))
1227                 return -ENOENT;
1228         return permission(dir,MAY_WRITE | MAY_EXEC, nd);
1229 }
1230
1231 /* 
1232  * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
1233  * reasons.
1234  *
1235  * O_DIRECTORY translates into forcing a directory lookup.
1236  */
1237 static inline int lookup_flags(unsigned int f)
1238 {
1239         unsigned long retval = LOOKUP_FOLLOW;
1240
1241         if (f & O_NOFOLLOW)
1242                 retval &= ~LOOKUP_FOLLOW;
1243         
1244         if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
1245                 retval &= ~LOOKUP_FOLLOW;
1246         
1247         if (f & O_DIRECTORY)
1248                 retval |= LOOKUP_DIRECTORY;
1249
1250         return retval;
1251 }
1252
1253 /*
1254  * p1 and p2 should be directories on the same fs.
1255  */
1256 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1257 {
1258         struct dentry *p;
1259
1260         if (p1 == p2) {
1261                 down(&p1->d_inode->i_sem);
1262                 return NULL;
1263         }
1264
1265         down(&p1->d_inode->i_sb->s_vfs_rename_sem);
1266
1267         for (p = p1; p->d_parent != p; p = p->d_parent) {
1268                 if (p->d_parent == p2) {
1269                         down(&p2->d_inode->i_sem);
1270                         down(&p1->d_inode->i_sem);
1271                         return p;
1272                 }
1273         }
1274
1275         for (p = p2; p->d_parent != p; p = p->d_parent) {
1276                 if (p->d_parent == p1) {
1277                         down(&p1->d_inode->i_sem);
1278                         down(&p2->d_inode->i_sem);
1279                         return p;
1280                 }
1281         }
1282
1283         down(&p1->d_inode->i_sem);
1284         down(&p2->d_inode->i_sem);
1285         return NULL;
1286 }
1287
1288 void unlock_rename(struct dentry *p1, struct dentry *p2)
1289 {
1290         up(&p1->d_inode->i_sem);
1291         if (p1 != p2) {
1292                 up(&p2->d_inode->i_sem);
1293                 up(&p1->d_inode->i_sb->s_vfs_rename_sem);
1294         }
1295 }
1296
1297 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1298                 struct nameidata *nd)
1299 {
1300         int error = may_create(dir, dentry, nd);
1301
1302         if (error)
1303                 return error;
1304
1305         if (!dir->i_op || !dir->i_op->create)
1306                 return -EACCES; /* shouldn't it be ENOSYS? */
1307         mode &= S_IALLUGO;
1308         mode |= S_IFREG;
1309         error = security_inode_create(dir, dentry, mode);
1310         if (error)
1311                 return error;
1312         DQUOT_INIT(dir);
1313         error = dir->i_op->create(dir, dentry, mode, nd);
1314         if (!error) {
1315                 fsnotify_create(dir, dentry->d_name.name);
1316                 security_inode_post_create(dir, dentry, mode);
1317         }
1318         return error;
1319 }
1320
1321 int may_open(struct nameidata *nd, int acc_mode, int flag)
1322 {
1323         struct dentry *dentry = nd->dentry;
1324         struct inode *inode = dentry->d_inode;
1325         int error;
1326
1327         if (!inode)
1328                 return -ENOENT;
1329
1330         if (S_ISLNK(inode->i_mode))
1331                 return -ELOOP;
1332         
1333         if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
1334                 return -EISDIR;
1335
1336         error = permission(inode, acc_mode, nd);
1337         if (error)
1338                 return error;
1339
1340         /*
1341          * FIFO's, sockets and device files are special: they don't
1342          * actually live on the filesystem itself, and as such you
1343          * can write to them even if the filesystem is read-only.
1344          */
1345         if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
1346                 flag &= ~O_TRUNC;
1347         } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
1348                 if (nd->mnt->mnt_flags & MNT_NODEV)
1349                         return -EACCES;
1350
1351                 flag &= ~O_TRUNC;
1352         } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
1353                 return -EROFS;
1354         /*
1355          * An append-only file must be opened in append mode for writing.
1356          */
1357         if (IS_APPEND(inode)) {
1358                 if  ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1359                         return -EPERM;
1360                 if (flag & O_TRUNC)
1361                         return -EPERM;
1362         }
1363
1364         /* O_NOATIME can only be set by the owner or superuser */
1365         if (flag & O_NOATIME)
1366                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
1367                         return -EPERM;
1368
1369         /*
1370          * Ensure there are no outstanding leases on the file.
1371          */
1372         error = break_lease(inode, flag);
1373         if (error)
1374                 return error;
1375
1376         if (flag & O_TRUNC) {
1377                 error = get_write_access(inode);
1378                 if (error)
1379                         return error;
1380
1381                 /*
1382                  * Refuse to truncate files with mandatory locks held on them.
1383                  */
1384                 error = locks_verify_locked(inode);
1385                 if (!error) {
1386                         DQUOT_INIT(inode);
1387                         
1388                         error = do_truncate(dentry, 0);
1389                 }
1390                 put_write_access(inode);
1391                 if (error)
1392                         return error;
1393         } else
1394                 if (flag & FMODE_WRITE)
1395                         DQUOT_INIT(inode);
1396
1397         return 0;
1398 }
1399
1400 /*
1401  *      open_namei()
1402  *
1403  * namei for open - this is in fact almost the whole open-routine.
1404  *
1405  * Note that the low bits of "flag" aren't the same as in the open
1406  * system call - they are 00 - no permissions needed
1407  *                        01 - read permission needed
1408  *                        10 - write permission needed
1409  *                        11 - read/write permissions needed
1410  * which is a lot more logical, and also allows the "no perm" needed
1411  * for symlinks (where the permissions are checked later).
1412  * SMP-safe
1413  */
1414 int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
1415 {
1416         int acc_mode, error = 0;
1417         struct path path;
1418         struct dentry *dir;
1419         int count = 0;
1420
1421         acc_mode = ACC_MODE(flag);
1422
1423         /* Allow the LSM permission hook to distinguish append 
1424            access from general write access. */
1425         if (flag & O_APPEND)
1426                 acc_mode |= MAY_APPEND;
1427
1428         /* Fill in the open() intent data */
1429         nd->intent.open.flags = flag;
1430         nd->intent.open.create_mode = mode;
1431
1432         /*
1433          * The simplest case - just a plain lookup.
1434          */
1435         if (!(flag & O_CREAT)) {
1436                 error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd);
1437                 if (error)
1438                         return error;
1439                 goto ok;
1440         }
1441
1442         /*
1443          * Create - we need to know the parent.
1444          */
1445         error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd);
1446         if (error)
1447                 return error;
1448
1449         /*
1450          * We have the parent and last component. First of all, check
1451          * that we are not asked to creat(2) an obvious directory - that
1452          * will not do.
1453          */
1454         error = -EISDIR;
1455         if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
1456                 goto exit;
1457
1458         dir = nd->dentry;
1459         nd->flags &= ~LOOKUP_PARENT;
1460         down(&dir->d_inode->i_sem);
1461         path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1462         path.mnt = nd->mnt;
1463
1464 do_last:
1465         error = PTR_ERR(path.dentry);
1466         if (IS_ERR(path.dentry)) {
1467                 up(&dir->d_inode->i_sem);
1468                 goto exit;
1469         }
1470
1471         /* Negative dentry, just create the file */
1472         if (!path.dentry->d_inode) {
1473                 if (!IS_POSIXACL(dir->d_inode))
1474                         mode &= ~current->fs->umask;
1475                 error = vfs_create(dir->d_inode, path.dentry, mode, nd);
1476                 up(&dir->d_inode->i_sem);
1477                 dput(nd->dentry);
1478                 nd->dentry = path.dentry;
1479                 if (error)
1480                         goto exit;
1481                 /* Don't check for write permission, don't truncate */
1482                 acc_mode = 0;
1483                 flag &= ~O_TRUNC;
1484                 goto ok;
1485         }
1486
1487         /*
1488          * It already exists.
1489          */
1490         up(&dir->d_inode->i_sem);
1491
1492         error = -EEXIST;
1493         if (flag & O_EXCL)
1494                 goto exit_dput;
1495
1496         if (__follow_mount(&path)) {
1497                 error = -ELOOP;
1498                 if (flag & O_NOFOLLOW)
1499                         goto exit_dput;
1500         }
1501         error = -ENOENT;
1502         if (!path.dentry->d_inode)
1503                 goto exit_dput;
1504         if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
1505                 goto do_link;
1506
1507         dput(nd->dentry);
1508         nd->dentry = path.dentry;
1509         if (nd->mnt != path.mnt)
1510                 mntput(nd->mnt);
1511         nd->mnt = path.mnt;
1512         error = -EISDIR;
1513         if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
1514                 goto exit;
1515 ok:
1516         error = may_open(nd, acc_mode, flag);
1517         if (error)
1518                 goto exit;
1519         return 0;
1520
1521 exit_dput:
1522         dput(path.dentry);
1523         if (nd->mnt != path.mnt)
1524                 mntput(path.mnt);
1525 exit:
1526         path_release(nd);
1527         return error;
1528
1529 do_link:
1530         error = -ELOOP;
1531         if (flag & O_NOFOLLOW)
1532                 goto exit_dput;
1533         /*
1534          * This is subtle. Instead of calling do_follow_link() we do the
1535          * thing by hands. The reason is that this way we have zero link_count
1536          * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1537          * After that we have the parent and last component, i.e.
1538          * we are in the same situation as after the first path_walk().
1539          * Well, almost - if the last component is normal we get its copy
1540          * stored in nd->last.name and we will have to putname() it when we
1541          * are done. Procfs-like symlinks just set LAST_BIND.
1542          */
1543         nd->flags |= LOOKUP_PARENT;
1544         error = security_inode_follow_link(path.dentry, nd);
1545         if (error)
1546                 goto exit_dput;
1547         error = __do_follow_link(&path, nd);
1548         if (error)
1549                 return error;
1550         nd->flags &= ~LOOKUP_PARENT;
1551         if (nd->last_type == LAST_BIND)
1552                 goto ok;
1553         error = -EISDIR;
1554         if (nd->last_type != LAST_NORM)
1555                 goto exit;
1556         if (nd->last.name[nd->last.len]) {
1557                 putname(nd->last.name);
1558                 goto exit;
1559         }
1560         error = -ELOOP;
1561         if (count++==32) {
1562                 putname(nd->last.name);
1563                 goto exit;
1564         }
1565         dir = nd->dentry;
1566         down(&dir->d_inode->i_sem);
1567         path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1568         path.mnt = nd->mnt;
1569         putname(nd->last.name);
1570         goto do_last;
1571 }
1572
1573 /**
1574  * lookup_create - lookup a dentry, creating it if it doesn't exist
1575  * @nd: nameidata info
1576  * @is_dir: directory flag
1577  *
1578  * Simple function to lookup and return a dentry and create it
1579  * if it doesn't exist.  Is SMP-safe.
1580  *
1581  * Returns with nd->dentry->d_inode->i_sem locked.
1582  */
1583 struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1584 {
1585         struct dentry *dentry = ERR_PTR(-EEXIST);
1586
1587         down(&nd->dentry->d_inode->i_sem);
1588         /*
1589          * Yucky last component or no last component at all?
1590          * (foo/., foo/.., /////)
1591          */
1592         if (nd->last_type != LAST_NORM)
1593                 goto fail;
1594         nd->flags &= ~LOOKUP_PARENT;
1595
1596         /*
1597          * Do the final lookup.
1598          */
1599         dentry = lookup_hash(&nd->last, nd->dentry);
1600         if (IS_ERR(dentry))
1601                 goto fail;
1602
1603         /*
1604          * Special case - lookup gave negative, but... we had foo/bar/
1605          * From the vfs_mknod() POV we just have a negative dentry -
1606          * all is fine. Let's be bastards - you had / on the end, you've
1607          * been asking for (non-existent) directory. -ENOENT for you.
1608          */
1609         if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
1610                 goto enoent;
1611         return dentry;
1612 enoent:
1613         dput(dentry);
1614         dentry = ERR_PTR(-ENOENT);
1615 fail:
1616         return dentry;
1617 }
1618 EXPORT_SYMBOL_GPL(lookup_create);
1619
1620 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1621 {
1622         int error = may_create(dir, dentry, NULL);
1623
1624         if (error)
1625                 return error;
1626
1627         if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1628                 return -EPERM;
1629
1630         if (!dir->i_op || !dir->i_op->mknod)
1631                 return -EPERM;
1632
1633         error = security_inode_mknod(dir, dentry, mode, dev);
1634         if (error)
1635                 return error;
1636
1637         DQUOT_INIT(dir);
1638         error = dir->i_op->mknod(dir, dentry, mode, dev);
1639         if (!error) {
1640                 fsnotify_create(dir, dentry->d_name.name);
1641                 security_inode_post_mknod(dir, dentry, mode, dev);
1642         }
1643         return error;
1644 }
1645
1646 asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev)
1647 {
1648         int error = 0;
1649         char * tmp;
1650         struct dentry * dentry;
1651         struct nameidata nd;
1652
1653         if (S_ISDIR(mode))
1654                 return -EPERM;
1655         tmp = getname(filename);
1656         if (IS_ERR(tmp))
1657                 return PTR_ERR(tmp);
1658
1659         error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1660         if (error)
1661                 goto out;
1662         dentry = lookup_create(&nd, 0);
1663         error = PTR_ERR(dentry);
1664
1665         if (!IS_POSIXACL(nd.dentry->d_inode))
1666                 mode &= ~current->fs->umask;
1667         if (!IS_ERR(dentry)) {
1668                 switch (mode & S_IFMT) {
1669                 case 0: case S_IFREG:
1670                         error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
1671                         break;
1672                 case S_IFCHR: case S_IFBLK:
1673                         error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
1674                                         new_decode_dev(dev));
1675                         break;
1676                 case S_IFIFO: case S_IFSOCK:
1677                         error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
1678                         break;
1679                 case S_IFDIR:
1680                         error = -EPERM;
1681                         break;
1682                 default:
1683                         error = -EINVAL;
1684                 }
1685                 dput(dentry);
1686         }
1687         up(&nd.dentry->d_inode->i_sem);
1688         path_release(&nd);
1689 out:
1690         putname(tmp);
1691
1692         return error;
1693 }
1694
1695 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1696 {
1697         int error = may_create(dir, dentry, NULL);
1698
1699         if (error)
1700                 return error;
1701
1702         if (!dir->i_op || !dir->i_op->mkdir)
1703                 return -EPERM;
1704
1705         mode &= (S_IRWXUGO|S_ISVTX);
1706         error = security_inode_mkdir(dir, dentry, mode);
1707         if (error)
1708                 return error;
1709
1710         DQUOT_INIT(dir);
1711         error = dir->i_op->mkdir(dir, dentry, mode);
1712         if (!error) {
1713                 fsnotify_mkdir(dir, dentry->d_name.name);
1714                 security_inode_post_mkdir(dir,dentry, mode);
1715         }
1716         return error;
1717 }
1718
1719 asmlinkage long sys_mkdir(const char __user * pathname, int mode)
1720 {
1721         int error = 0;
1722         char * tmp;
1723
1724         tmp = getname(pathname);
1725         error = PTR_ERR(tmp);
1726         if (!IS_ERR(tmp)) {
1727                 struct dentry *dentry;
1728                 struct nameidata nd;
1729
1730                 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1731                 if (error)
1732                         goto out;
1733                 dentry = lookup_create(&nd, 1);
1734                 error = PTR_ERR(dentry);
1735                 if (!IS_ERR(dentry)) {
1736                         if (!IS_POSIXACL(nd.dentry->d_inode))
1737                                 mode &= ~current->fs->umask;
1738                         error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
1739                         dput(dentry);
1740                 }
1741                 up(&nd.dentry->d_inode->i_sem);
1742                 path_release(&nd);
1743 out:
1744                 putname(tmp);
1745         }
1746
1747         return error;
1748 }
1749
1750 /*
1751  * We try to drop the dentry early: we should have
1752  * a usage count of 2 if we're the only user of this
1753  * dentry, and if that is true (possibly after pruning
1754  * the dcache), then we drop the dentry now.
1755  *
1756  * A low-level filesystem can, if it choses, legally
1757  * do a
1758  *
1759  *      if (!d_unhashed(dentry))
1760  *              return -EBUSY;
1761  *
1762  * if it cannot handle the case of removing a directory
1763  * that is still in use by something else..
1764  */
1765 void dentry_unhash(struct dentry *dentry)
1766 {
1767         dget(dentry);
1768         if (atomic_read(&dentry->d_count))
1769                 shrink_dcache_parent(dentry);
1770         spin_lock(&dcache_lock);
1771         spin_lock(&dentry->d_lock);
1772         if (atomic_read(&dentry->d_count) == 2)
1773                 __d_drop(dentry);
1774         spin_unlock(&dentry->d_lock);
1775         spin_unlock(&dcache_lock);
1776 }
1777
1778 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
1779 {
1780         int error = may_delete(dir, dentry, 1);
1781
1782         if (error)
1783                 return error;
1784
1785         if (!dir->i_op || !dir->i_op->rmdir)
1786                 return -EPERM;
1787
1788         DQUOT_INIT(dir);
1789
1790         down(&dentry->d_inode->i_sem);
1791         dentry_unhash(dentry);
1792         if (d_mountpoint(dentry))
1793                 error = -EBUSY;
1794         else {
1795                 error = security_inode_rmdir(dir, dentry);
1796                 if (!error) {
1797                         error = dir->i_op->rmdir(dir, dentry);
1798                         if (!error)
1799                                 dentry->d_inode->i_flags |= S_DEAD;
1800                 }
1801         }
1802         up(&dentry->d_inode->i_sem);
1803         if (!error) {
1804                 fsnotify_rmdir(dentry, dentry->d_inode, dir);
1805                 d_delete(dentry);
1806         }
1807         dput(dentry);
1808
1809         return error;
1810 }
1811
1812 asmlinkage long sys_rmdir(const char __user * pathname)
1813 {
1814         int error = 0;
1815         char * name;
1816         struct dentry *dentry;
1817         struct nameidata nd;
1818
1819         name = getname(pathname);
1820         if(IS_ERR(name))
1821                 return PTR_ERR(name);
1822
1823         error = path_lookup(name, LOOKUP_PARENT, &nd);
1824         if (error)
1825                 goto exit;
1826
1827         switch(nd.last_type) {
1828                 case LAST_DOTDOT:
1829                         error = -ENOTEMPTY;
1830                         goto exit1;
1831                 case LAST_DOT:
1832                         error = -EINVAL;
1833                         goto exit1;
1834                 case LAST_ROOT:
1835                         error = -EBUSY;
1836                         goto exit1;
1837         }
1838         down(&nd.dentry->d_inode->i_sem);
1839         dentry = lookup_hash(&nd.last, nd.dentry);
1840         error = PTR_ERR(dentry);
1841         if (!IS_ERR(dentry)) {
1842                 error = vfs_rmdir(nd.dentry->d_inode, dentry);
1843                 dput(dentry);
1844         }
1845         up(&nd.dentry->d_inode->i_sem);
1846 exit1:
1847         path_release(&nd);
1848 exit:
1849         putname(name);
1850         return error;
1851 }
1852
1853 int vfs_unlink(struct inode *dir, struct dentry *dentry)
1854 {
1855         int error = may_delete(dir, dentry, 0);
1856
1857         if (error)
1858                 return error;
1859
1860         if (!dir->i_op || !dir->i_op->unlink)
1861                 return -EPERM;
1862
1863         DQUOT_INIT(dir);
1864
1865         down(&dentry->d_inode->i_sem);
1866         if (d_mountpoint(dentry))
1867                 error = -EBUSY;
1868         else {
1869                 error = security_inode_unlink(dir, dentry);
1870                 if (!error)
1871                         error = dir->i_op->unlink(dir, dentry);
1872         }
1873         up(&dentry->d_inode->i_sem);
1874
1875         /* We don't d_delete() NFS sillyrenamed files--they still exist. */
1876         if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
1877                 fsnotify_unlink(dentry, dir);
1878                 d_delete(dentry);
1879         }
1880
1881         return error;
1882 }
1883
1884 /*
1885  * Make sure that the actual truncation of the file will occur outside its
1886  * directory's i_sem.  Truncate can take a long time if there is a lot of
1887  * writeout happening, and we don't want to prevent access to the directory
1888  * while waiting on the I/O.
1889  */
1890 asmlinkage long sys_unlink(const char __user * pathname)
1891 {
1892         int error = 0;
1893         char * name;
1894         struct dentry *dentry;
1895         struct nameidata nd;
1896         struct inode *inode = NULL;
1897
1898         name = getname(pathname);
1899         if(IS_ERR(name))
1900                 return PTR_ERR(name);
1901
1902         error = path_lookup(name, LOOKUP_PARENT, &nd);
1903         if (error)
1904                 goto exit;
1905         error = -EISDIR;
1906         if (nd.last_type != LAST_NORM)
1907                 goto exit1;
1908         down(&nd.dentry->d_inode->i_sem);
1909         dentry = lookup_hash(&nd.last, nd.dentry);
1910         error = PTR_ERR(dentry);
1911         if (!IS_ERR(dentry)) {
1912                 /* Why not before? Because we want correct error value */
1913                 if (nd.last.name[nd.last.len])
1914                         goto slashes;
1915                 inode = dentry->d_inode;
1916                 if (inode)
1917                         atomic_inc(&inode->i_count);
1918                 error = vfs_unlink(nd.dentry->d_inode, dentry);
1919         exit2:
1920                 dput(dentry);
1921         }
1922         up(&nd.dentry->d_inode->i_sem);
1923         if (inode)
1924                 iput(inode);    /* truncate the inode here */
1925 exit1:
1926         path_release(&nd);
1927 exit:
1928         putname(name);
1929         return error;
1930
1931 slashes:
1932         error = !dentry->d_inode ? -ENOENT :
1933                 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
1934         goto exit2;
1935 }
1936
1937 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
1938 {
1939         int error = may_create(dir, dentry, NULL);
1940
1941         if (error)
1942                 return error;
1943
1944         if (!dir->i_op || !dir->i_op->symlink)
1945                 return -EPERM;
1946
1947         error = security_inode_symlink(dir, dentry, oldname);
1948         if (error)
1949                 return error;
1950
1951         DQUOT_INIT(dir);
1952         error = dir->i_op->symlink(dir, dentry, oldname);
1953         if (!error) {
1954                 fsnotify_create(dir, dentry->d_name.name);
1955                 security_inode_post_symlink(dir, dentry, oldname);
1956         }
1957         return error;
1958 }
1959
1960 asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname)
1961 {
1962         int error = 0;
1963         char * from;
1964         char * to;
1965
1966         from = getname(oldname);
1967         if(IS_ERR(from))
1968                 return PTR_ERR(from);
1969         to = getname(newname);
1970         error = PTR_ERR(to);
1971         if (!IS_ERR(to)) {
1972                 struct dentry *dentry;
1973                 struct nameidata nd;
1974
1975                 error = path_lookup(to, LOOKUP_PARENT, &nd);
1976                 if (error)
1977                         goto out;
1978                 dentry = lookup_create(&nd, 0);
1979                 error = PTR_ERR(dentry);
1980                 if (!IS_ERR(dentry)) {
1981                         error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
1982                         dput(dentry);
1983                 }
1984                 up(&nd.dentry->d_inode->i_sem);
1985                 path_release(&nd);
1986 out:
1987                 putname(to);
1988         }
1989         putname(from);
1990         return error;
1991 }
1992
1993 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
1994 {
1995         struct inode *inode = old_dentry->d_inode;
1996         int error;
1997
1998         if (!inode)
1999                 return -ENOENT;
2000
2001         error = may_create(dir, new_dentry, NULL);
2002         if (error)
2003                 return error;
2004
2005         if (dir->i_sb != inode->i_sb)
2006                 return -EXDEV;
2007
2008         /*
2009          * A link to an append-only or immutable file cannot be created.
2010          */
2011         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2012                 return -EPERM;
2013         if (!dir->i_op || !dir->i_op->link)
2014                 return -EPERM;
2015         if (S_ISDIR(old_dentry->d_inode->i_mode))
2016                 return -EPERM;
2017
2018         error = security_inode_link(old_dentry, dir, new_dentry);
2019         if (error)
2020                 return error;
2021
2022         down(&old_dentry->d_inode->i_sem);
2023         DQUOT_INIT(dir);
2024         error = dir->i_op->link(old_dentry, dir, new_dentry);
2025         up(&old_dentry->d_inode->i_sem);
2026         if (!error) {
2027                 fsnotify_create(dir, new_dentry->d_name.name);
2028                 security_inode_post_link(old_dentry, dir, new_dentry);
2029         }
2030         return error;
2031 }
2032
2033 /*
2034  * Hardlinks are often used in delicate situations.  We avoid
2035  * security-related surprises by not following symlinks on the
2036  * newname.  --KAB
2037  *
2038  * We don't follow them on the oldname either to be compatible
2039  * with linux 2.0, and to avoid hard-linking to directories
2040  * and other special files.  --ADM
2041  */
2042 asmlinkage long sys_link(const char __user * oldname, const char __user * newname)
2043 {
2044         struct dentry *new_dentry;
2045         struct nameidata nd, old_nd;
2046         int error;
2047         char * to;
2048
2049         to = getname(newname);
2050         if (IS_ERR(to))
2051                 return PTR_ERR(to);
2052
2053         error = __user_walk(oldname, 0, &old_nd);
2054         if (error)
2055                 goto exit;
2056         error = path_lookup(to, LOOKUP_PARENT, &nd);
2057         if (error)
2058                 goto out;
2059         error = -EXDEV;
2060         if (old_nd.mnt != nd.mnt)
2061                 goto out_release;
2062         new_dentry = lookup_create(&nd, 0);
2063         error = PTR_ERR(new_dentry);
2064         if (!IS_ERR(new_dentry)) {
2065                 error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
2066                 dput(new_dentry);
2067         }
2068         up(&nd.dentry->d_inode->i_sem);
2069 out_release:
2070         path_release(&nd);
2071 out:
2072         path_release(&old_nd);
2073 exit:
2074         putname(to);
2075
2076         return error;
2077 }
2078
2079 /*
2080  * The worst of all namespace operations - renaming directory. "Perverted"
2081  * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2082  * Problems:
2083  *      a) we can get into loop creation. Check is done in is_subdir().
2084  *      b) race potential - two innocent renames can create a loop together.
2085  *         That's where 4.4 screws up. Current fix: serialization on
2086  *         sb->s_vfs_rename_sem. We might be more accurate, but that's another
2087  *         story.
2088  *      c) we have to lock _three_ objects - parents and victim (if it exists).
2089  *         And that - after we got ->i_sem on parents (until then we don't know
2090  *         whether the target exists).  Solution: try to be smart with locking
2091  *         order for inodes.  We rely on the fact that tree topology may change
2092  *         only under ->s_vfs_rename_sem _and_ that parent of the object we
2093  *         move will be locked.  Thus we can rank directories by the tree
2094  *         (ancestors first) and rank all non-directories after them.
2095  *         That works since everybody except rename does "lock parent, lookup,
2096  *         lock child" and rename is under ->s_vfs_rename_sem.
2097  *         HOWEVER, it relies on the assumption that any object with ->lookup()
2098  *         has no more than 1 dentry.  If "hybrid" objects will ever appear,
2099  *         we'd better make sure that there's no link(2) for them.
2100  *      d) some filesystems don't support opened-but-unlinked directories,
2101  *         either because of layout or because they are not ready to deal with
2102  *         all cases correctly. The latter will be fixed (taking this sort of
2103  *         stuff into VFS), but the former is not going away. Solution: the same
2104  *         trick as in rmdir().
2105  *      e) conversion from fhandle to dentry may come in the wrong moment - when
2106  *         we are removing the target. Solution: we will have to grab ->i_sem
2107  *         in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2108  *         ->i_sem on parents, which works but leads to some truely excessive
2109  *         locking].
2110  */
2111 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2112                           struct inode *new_dir, struct dentry *new_dentry)
2113 {
2114         int error = 0;
2115         struct inode *target;
2116
2117         /*
2118          * If we are going to change the parent - check write permissions,
2119          * we'll need to flip '..'.
2120          */
2121         if (new_dir != old_dir) {
2122                 error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
2123                 if (error)
2124                         return error;
2125         }
2126
2127         error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2128         if (error)
2129                 return error;
2130
2131         target = new_dentry->d_inode;
2132         if (target) {
2133                 down(&target->i_sem);
2134                 dentry_unhash(new_dentry);
2135         }
2136         if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2137                 error = -EBUSY;
2138         else 
2139                 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2140         if (target) {
2141                 if (!error)
2142                         target->i_flags |= S_DEAD;
2143                 up(&target->i_sem);
2144                 if (d_unhashed(new_dentry))
2145                         d_rehash(new_dentry);
2146                 dput(new_dentry);
2147         }
2148         if (!error) {
2149                 d_move(old_dentry,new_dentry);
2150                 security_inode_post_rename(old_dir, old_dentry,
2151                                            new_dir, new_dentry);
2152         }
2153         return error;
2154 }
2155
2156 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2157                             struct inode *new_dir, struct dentry *new_dentry)
2158 {
2159         struct inode *target;
2160         int error;
2161
2162         error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2163         if (error)
2164                 return error;
2165
2166         dget(new_dentry);
2167         target = new_dentry->d_inode;
2168         if (target)
2169                 down(&target->i_sem);
2170         if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2171                 error = -EBUSY;
2172         else
2173                 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2174         if (!error) {
2175                 /* The following d_move() should become unconditional */
2176                 if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME))
2177                         d_move(old_dentry, new_dentry);
2178                 security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry);
2179         }
2180         if (target)
2181                 up(&target->i_sem);
2182         dput(new_dentry);
2183         return error;
2184 }
2185
2186 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2187                struct inode *new_dir, struct dentry *new_dentry)
2188 {
2189         int error;
2190         int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2191         const char *old_name;
2192
2193         if (old_dentry->d_inode == new_dentry->d_inode)
2194                 return 0;
2195  
2196         error = may_delete(old_dir, old_dentry, is_dir);
2197         if (error)
2198                 return error;
2199
2200         if (!new_dentry->d_inode)
2201                 error = may_create(new_dir, new_dentry, NULL);
2202         else
2203                 error = may_delete(new_dir, new_dentry, is_dir);
2204         if (error)
2205                 return error;
2206
2207         if (!old_dir->i_op || !old_dir->i_op->rename)
2208                 return -EPERM;
2209
2210         DQUOT_INIT(old_dir);
2211         DQUOT_INIT(new_dir);
2212
2213         old_name = fsnotify_oldname_init(old_dentry->d_name.name);
2214
2215         if (is_dir)
2216                 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2217         else
2218                 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2219         if (!error) {
2220                 const char *new_name = old_dentry->d_name.name;
2221                 fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir);
2222         }
2223         fsnotify_oldname_free(old_name);
2224
2225         return error;
2226 }
2227
2228 static inline int do_rename(const char * oldname, const char * newname)
2229 {
2230         int error = 0;
2231         struct dentry * old_dir, * new_dir;
2232         struct dentry * old_dentry, *new_dentry;
2233         struct dentry * trap;
2234         struct nameidata oldnd, newnd;
2235
2236         error = path_lookup(oldname, LOOKUP_PARENT, &oldnd);
2237         if (error)
2238                 goto exit;
2239
2240         error = path_lookup(newname, LOOKUP_PARENT, &newnd);
2241         if (error)
2242                 goto exit1;
2243
2244         error = -EXDEV;
2245         if (oldnd.mnt != newnd.mnt)
2246                 goto exit2;
2247
2248         old_dir = oldnd.dentry;
2249         error = -EBUSY;
2250         if (oldnd.last_type != LAST_NORM)
2251                 goto exit2;
2252
2253         new_dir = newnd.dentry;
2254         if (newnd.last_type != LAST_NORM)
2255                 goto exit2;
2256
2257         trap = lock_rename(new_dir, old_dir);
2258
2259         old_dentry = lookup_hash(&oldnd.last, old_dir);
2260         error = PTR_ERR(old_dentry);
2261         if (IS_ERR(old_dentry))
2262                 goto exit3;
2263         /* source must exist */
2264         error = -ENOENT;
2265         if (!old_dentry->d_inode)
2266                 goto exit4;
2267         /* unless the source is a directory trailing slashes give -ENOTDIR */
2268         if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2269                 error = -ENOTDIR;
2270                 if (oldnd.last.name[oldnd.last.len])
2271                         goto exit4;
2272                 if (newnd.last.name[newnd.last.len])
2273                         goto exit4;
2274         }
2275         /* source should not be ancestor of target */
2276         error = -EINVAL;
2277         if (old_dentry == trap)
2278                 goto exit4;
2279         new_dentry = lookup_hash(&newnd.last, new_dir);
2280         error = PTR_ERR(new_dentry);
2281         if (IS_ERR(new_dentry))
2282                 goto exit4;
2283         /* target should not be an ancestor of source */
2284         error = -ENOTEMPTY;
2285         if (new_dentry == trap)
2286                 goto exit5;
2287
2288         error = vfs_rename(old_dir->d_inode, old_dentry,
2289                                    new_dir->d_inode, new_dentry);
2290 exit5:
2291         dput(new_dentry);
2292 exit4:
2293         dput(old_dentry);
2294 exit3:
2295         unlock_rename(new_dir, old_dir);
2296 exit2:
2297         path_release(&newnd);
2298 exit1:
2299         path_release(&oldnd);
2300 exit:
2301         return error;
2302 }
2303
2304 asmlinkage long sys_rename(const char __user * oldname, const char __user * newname)
2305 {
2306         int error;
2307         char * from;
2308         char * to;
2309
2310         from = getname(oldname);
2311         if(IS_ERR(from))
2312                 return PTR_ERR(from);
2313         to = getname(newname);
2314         error = PTR_ERR(to);
2315         if (!IS_ERR(to)) {
2316                 error = do_rename(from,to);
2317                 putname(to);
2318         }
2319         putname(from);
2320         return error;
2321 }
2322
2323 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2324 {
2325         int len;
2326
2327         len = PTR_ERR(link);
2328         if (IS_ERR(link))
2329                 goto out;
2330
2331         len = strlen(link);
2332         if (len > (unsigned) buflen)
2333                 len = buflen;
2334         if (copy_to_user(buffer, link, len))
2335                 len = -EFAULT;
2336 out:
2337         return len;
2338 }
2339
2340 /*
2341  * A helper for ->readlink().  This should be used *ONLY* for symlinks that
2342  * have ->follow_link() touching nd only in nd_set_link().  Using (or not
2343  * using) it for any given inode is up to filesystem.
2344  */
2345 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2346 {
2347         struct nameidata nd;
2348         int res;
2349         nd.depth = 0;
2350         res = dentry->d_inode->i_op->follow_link(dentry, &nd);
2351         if (!res) {
2352                 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2353                 if (dentry->d_inode->i_op->put_link)
2354                         dentry->d_inode->i_op->put_link(dentry, &nd);
2355         }
2356         return res;
2357 }
2358
2359 int vfs_follow_link(struct nameidata *nd, const char *link)
2360 {
2361         return __vfs_follow_link(nd, link);
2362 }
2363
2364 /* get the link contents into pagecache */
2365 static char *page_getlink(struct dentry * dentry, struct page **ppage)
2366 {
2367         struct page * page;
2368         struct address_space *mapping = dentry->d_inode->i_mapping;
2369         page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
2370                                 NULL);
2371         if (IS_ERR(page))
2372                 goto sync_fail;
2373         wait_on_page_locked(page);
2374         if (!PageUptodate(page))
2375                 goto async_fail;
2376         *ppage = page;
2377         return kmap(page);
2378
2379 async_fail:
2380         page_cache_release(page);
2381         return ERR_PTR(-EIO);
2382
2383 sync_fail:
2384         return (char*)page;
2385 }
2386
2387 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2388 {
2389         struct page *page = NULL;
2390         char *s = page_getlink(dentry, &page);
2391         int res = vfs_readlink(dentry,buffer,buflen,s);
2392         if (page) {
2393                 kunmap(page);
2394                 page_cache_release(page);
2395         }
2396         return res;
2397 }
2398
2399 int page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
2400 {
2401         struct page *page;
2402         nd_set_link(nd, page_getlink(dentry, &page));
2403         return 0;
2404 }
2405
2406 void page_put_link(struct dentry *dentry, struct nameidata *nd)
2407 {
2408         if (!IS_ERR(nd_get_link(nd))) {
2409                 struct page *page;
2410                 page = find_get_page(dentry->d_inode->i_mapping, 0);
2411                 if (!page)
2412                         BUG();
2413                 kunmap(page);
2414                 page_cache_release(page);
2415                 page_cache_release(page);
2416         }
2417 }
2418
2419 int page_symlink(struct inode *inode, const char *symname, int len)
2420 {
2421         struct address_space *mapping = inode->i_mapping;
2422         struct page *page = grab_cache_page(mapping, 0);
2423         int err = -ENOMEM;
2424         char *kaddr;
2425
2426         if (!page)
2427                 goto fail;
2428         err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
2429         if (err)
2430                 goto fail_map;
2431         kaddr = kmap_atomic(page, KM_USER0);
2432         memcpy(kaddr, symname, len-1);
2433         kunmap_atomic(kaddr, KM_USER0);
2434         mapping->a_ops->commit_write(NULL, page, 0, len-1);
2435         /*
2436          * Notice that we are _not_ going to block here - end of page is
2437          * unmapped, so this will only try to map the rest of page, see
2438          * that it is unmapped (typically even will not look into inode -
2439          * ->i_size will be enough for everything) and zero it out.
2440          * OTOH it's obviously correct and should make the page up-to-date.
2441          */
2442         if (!PageUptodate(page)) {
2443                 err = mapping->a_ops->readpage(NULL, page);
2444                 wait_on_page_locked(page);
2445         } else {
2446                 unlock_page(page);
2447         }
2448         page_cache_release(page);
2449         if (err < 0)
2450                 goto fail;
2451         mark_inode_dirty(inode);
2452         return 0;
2453 fail_map:
2454         unlock_page(page);
2455         page_cache_release(page);
2456 fail:
2457         return err;
2458 }
2459
2460 struct inode_operations page_symlink_inode_operations = {
2461         .readlink       = generic_readlink,
2462         .follow_link    = page_follow_link_light,
2463         .put_link       = page_put_link,
2464 };
2465
2466 EXPORT_SYMBOL(__user_walk);
2467 EXPORT_SYMBOL(follow_down);
2468 EXPORT_SYMBOL(follow_up);
2469 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2470 EXPORT_SYMBOL(getname);
2471 EXPORT_SYMBOL(lock_rename);
2472 EXPORT_SYMBOL(lookup_hash);
2473 EXPORT_SYMBOL(lookup_one_len);
2474 EXPORT_SYMBOL(page_follow_link_light);
2475 EXPORT_SYMBOL(page_put_link);
2476 EXPORT_SYMBOL(page_readlink);
2477 EXPORT_SYMBOL(page_symlink);
2478 EXPORT_SYMBOL(page_symlink_inode_operations);
2479 EXPORT_SYMBOL(path_lookup);
2480 EXPORT_SYMBOL(path_release);
2481 EXPORT_SYMBOL(path_walk);
2482 EXPORT_SYMBOL(permission);
2483 EXPORT_SYMBOL(unlock_rename);
2484 EXPORT_SYMBOL(vfs_create);
2485 EXPORT_SYMBOL(vfs_follow_link);
2486 EXPORT_SYMBOL(vfs_link);
2487 EXPORT_SYMBOL(vfs_mkdir);
2488 EXPORT_SYMBOL(vfs_mknod);
2489 EXPORT_SYMBOL(generic_permission);
2490 EXPORT_SYMBOL(vfs_readlink);
2491 EXPORT_SYMBOL(vfs_rename);
2492 EXPORT_SYMBOL(vfs_rmdir);
2493 EXPORT_SYMBOL(vfs_symlink);
2494 EXPORT_SYMBOL(vfs_unlink);
2495 EXPORT_SYMBOL(dentry_unhash);
2496 EXPORT_SYMBOL(generic_readlink);