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[linux-2.6/verdex.git] / fs / namei.c
blob145e852c4bd02d717c3dd9e3b63caa6804870f25
1 /*
2 * linux/fs/namei.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 /*
8 * Some corrections by tytso.
9 */
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
12 * lookup logic.
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
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>
34 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
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).
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.
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.
53 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
54 * resolution to correspond with current state of the code.
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.
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.
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.
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.
84 * [10-Sep-98 Alan Modra] Another symlink change.
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).
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...
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...
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..
111 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
112 * PATH_MAX includes the nul terminator --RR.
114 static inline int do_getname(const char __user *filename, char *page)
116 int retval;
117 unsigned long len = PATH_MAX;
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;
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;
136 char * getname(const char __user * filename)
138 char *tmp, *result;
140 result = ERR_PTR(-ENOMEM);
141 tmp = __getname();
142 if (tmp) {
143 int retval = do_getname(filename, tmp);
145 result = tmp;
146 if (retval < 0) {
147 __putname(tmp);
148 result = ERR_PTR(retval);
151 audit_getname(result);
152 return result;
155 #ifdef CONFIG_AUDITSYSCALL
156 void putname(const char *name)
158 if (unlikely(current->audit_context))
159 audit_putname(name);
160 else
161 __putname(name);
163 EXPORT_SYMBOL(putname);
164 #endif
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
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..
178 int generic_permission(struct inode *inode, int mask,
179 int (*check_acl)(struct inode *inode, int mask))
181 umode_t mode = inode->i_mode;
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;
194 if (in_group_p(inode->i_gid))
195 mode >>= 3;
199 * If the DACs are ok we don't need any capability check.
201 if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask))
202 return 0;
204 check_capabilities:
206 * Read/write DACs are always overridable.
207 * Executable DACs are overridable if at least one exec bit is set.
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;
215 * Searching includes executable on directories, else just read.
217 if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
218 if (capable(CAP_DAC_READ_SEARCH))
219 return 0;
221 return -EACCES;
224 int permission(struct inode *inode, int mask, struct nameidata *nd)
226 int retval, submask;
228 if (mask & MAY_WRITE) {
229 umode_t mode = inode->i_mode;
232 * Nobody gets write access to a read-only fs.
234 if (IS_RDONLY(inode) &&
235 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
236 return -EROFS;
239 * Nobody gets write access to an immutable file.
241 if (IS_IMMUTABLE(inode))
242 return -EACCES;
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;
255 return security_inode_permission(inode, mask, nd);
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.
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.
276 int get_write_access(struct inode * inode)
278 spin_lock(&inode->i_lock);
279 if (atomic_read(&inode->i_writecount) < 0) {
280 spin_unlock(&inode->i_lock);
281 return -ETXTBSY;
283 atomic_inc(&inode->i_writecount);
284 spin_unlock(&inode->i_lock);
286 return 0;
289 int deny_write_access(struct file * file)
291 struct inode *inode = file->f_dentry->d_inode;
293 spin_lock(&inode->i_lock);
294 if (atomic_read(&inode->i_writecount) > 0) {
295 spin_unlock(&inode->i_lock);
296 return -ETXTBSY;
298 atomic_dec(&inode->i_writecount);
299 spin_unlock(&inode->i_lock);
301 return 0;
304 void path_release(struct nameidata *nd)
306 dput(nd->dentry);
307 mntput(nd->mnt);
311 * umount() mustn't call path_release()/mntput() as that would clear
312 * mnt_expiry_mark
314 void path_release_on_umount(struct nameidata *nd)
316 dput(nd->dentry);
317 mntput_no_expire(nd->mnt);
321 * Internal lookup() using the new generic dcache.
322 * SMP-safe
324 static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
326 struct dentry * dentry = __d_lookup(parent, name);
328 /* lockess __d_lookup may fail due to concurrent d_move()
329 * in some unrelated directory, so try with d_lookup
331 if (!dentry)
332 dentry = d_lookup(parent, name);
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;
340 return dentry;
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.
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.
353 static inline int exec_permission_lite(struct inode *inode,
354 struct nameidata *nd)
356 umode_t mode = inode->i_mode;
358 if (inode->i_op && inode->i_op->permission)
359 return -EAGAIN;
361 if (current->fsuid == inode->i_uid)
362 mode >>= 6;
363 else if (in_group_p(inode->i_gid))
364 mode >>= 3;
366 if (mode & MAY_EXEC)
367 goto ok;
369 if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
370 goto ok;
372 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
373 goto ok;
375 if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
376 goto ok;
378 return -EACCES;
380 return security_inode_permission(inode, MAY_EXEC, nd);
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..
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
391 static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
393 struct dentry * result;
394 struct inode *dir = parent->d_inode;
396 down(&dir->i_sem);
398 * First re-do the cached lookup just in case it was created
399 * while we waited for the directory semaphore..
401 * FIXME! This could use version numbering or similar to
402 * avoid unnecessary cache lookups.
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).
409 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
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;
422 up(&dir->i_sem);
423 return result;
427 * Uhhuh! Nasty case: the cache was re-populated while
428 * we waited on the semaphore. Need to revalidate.
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);
437 return result;
440 static int __emul_lookup_dentry(const char *, struct nameidata *);
442 /* SMP-safe */
443 static inline int
444 walk_init_root(const char *name, struct nameidata *nd)
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);
455 nd->mnt = mntget(current->fs->rootmnt);
456 nd->dentry = dget(current->fs->root);
457 read_unlock(&current->fs->lock);
458 return 1;
461 static inline int __vfs_follow_link(struct nameidata *nd, const char *link)
463 int res = 0;
464 char *name;
465 if (IS_ERR(link))
466 goto fail;
468 if (*link == '/') {
469 path_release(nd);
470 if (!walk_init_root(link, nd))
471 /* weird __emul_prefix() stuff did it */
472 goto out;
474 res = link_path_walk(link, nd);
475 out:
476 if (nd->depth || res || nd->last_type!=LAST_NORM)
477 return res;
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...
483 name = __getname();
484 if (unlikely(!name)) {
485 path_release(nd);
486 return -ENOMEM;
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);
496 struct path {
497 struct vfsmount *mnt;
498 struct dentry *dentry;
501 static inline int __do_follow_link(struct path *path, struct nameidata *nd)
503 int error;
504 void *cookie;
505 struct dentry *dentry = path->dentry;
507 touch_atime(path->mnt, dentry);
508 nd_set_link(nd, NULL);
510 if (path->mnt == nd->mnt)
511 mntget(path->mnt);
512 cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
513 error = PTR_ERR(cookie);
514 if (!IS_ERR(cookie)) {
515 char *s = nd_get_link(nd);
516 error = 0;
517 if (s)
518 error = __vfs_follow_link(nd, s);
519 if (dentry->d_inode->i_op->put_link)
520 dentry->d_inode->i_op->put_link(dentry, nd, cookie);
522 dput(dentry);
523 mntput(path->mnt);
525 return error;
528 static inline void dput_path(struct path *path, struct nameidata *nd)
530 dput(path->dentry);
531 if (path->mnt != nd->mnt)
532 mntput(path->mnt);
535 static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
537 dput(nd->dentry);
538 if (nd->mnt != path->mnt)
539 mntput(nd->mnt);
540 nd->mnt = path->mnt;
541 nd->dentry = path->dentry;
545 * This limits recursive symlink follows to 8, while
546 * limiting consecutive symlinks to 40.
548 * Without that kind of total limit, nasty chains of consecutive
549 * symlinks can cause almost arbitrarily long lookups.
551 static inline int do_follow_link(struct path *path, struct nameidata *nd)
553 int err = -ELOOP;
554 if (current->link_count >= MAX_NESTED_LINKS)
555 goto loop;
556 if (current->total_link_count >= 40)
557 goto loop;
558 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
559 cond_resched();
560 err = security_inode_follow_link(path->dentry, nd);
561 if (err)
562 goto loop;
563 current->link_count++;
564 current->total_link_count++;
565 nd->depth++;
566 err = __do_follow_link(path, nd);
567 current->link_count--;
568 nd->depth--;
569 return err;
570 loop:
571 dput_path(path, nd);
572 path_release(nd);
573 return err;
576 int follow_up(struct vfsmount **mnt, struct dentry **dentry)
578 struct vfsmount *parent;
579 struct dentry *mountpoint;
580 spin_lock(&vfsmount_lock);
581 parent=(*mnt)->mnt_parent;
582 if (parent == *mnt) {
583 spin_unlock(&vfsmount_lock);
584 return 0;
586 mntget(parent);
587 mountpoint=dget((*mnt)->mnt_mountpoint);
588 spin_unlock(&vfsmount_lock);
589 dput(*dentry);
590 *dentry = mountpoint;
591 mntput(*mnt);
592 *mnt = parent;
593 return 1;
596 /* no need for dcache_lock, as serialization is taken care in
597 * namespace.c
599 static int __follow_mount(struct path *path)
601 int res = 0;
602 while (d_mountpoint(path->dentry)) {
603 struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
604 if (!mounted)
605 break;
606 dput(path->dentry);
607 if (res)
608 mntput(path->mnt);
609 path->mnt = mounted;
610 path->dentry = dget(mounted->mnt_root);
611 res = 1;
613 return res;
616 static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
618 while (d_mountpoint(*dentry)) {
619 struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
620 if (!mounted)
621 break;
622 dput(*dentry);
623 mntput(*mnt);
624 *mnt = mounted;
625 *dentry = dget(mounted->mnt_root);
629 /* no need for dcache_lock, as serialization is taken care in
630 * namespace.c
632 int follow_down(struct vfsmount **mnt, struct dentry **dentry)
634 struct vfsmount *mounted;
636 mounted = lookup_mnt(*mnt, *dentry);
637 if (mounted) {
638 dput(*dentry);
639 mntput(*mnt);
640 *mnt = mounted;
641 *dentry = dget(mounted->mnt_root);
642 return 1;
644 return 0;
647 static inline void follow_dotdot(struct nameidata *nd)
649 while(1) {
650 struct vfsmount *parent;
651 struct dentry *old = nd->dentry;
653 read_lock(&current->fs->lock);
654 if (nd->dentry == current->fs->root &&
655 nd->mnt == current->fs->rootmnt) {
656 read_unlock(&current->fs->lock);
657 break;
659 read_unlock(&current->fs->lock);
660 spin_lock(&dcache_lock);
661 if (nd->dentry != nd->mnt->mnt_root) {
662 nd->dentry = dget(nd->dentry->d_parent);
663 spin_unlock(&dcache_lock);
664 dput(old);
665 break;
667 spin_unlock(&dcache_lock);
668 spin_lock(&vfsmount_lock);
669 parent = nd->mnt->mnt_parent;
670 if (parent == nd->mnt) {
671 spin_unlock(&vfsmount_lock);
672 break;
674 mntget(parent);
675 nd->dentry = dget(nd->mnt->mnt_mountpoint);
676 spin_unlock(&vfsmount_lock);
677 dput(old);
678 mntput(nd->mnt);
679 nd->mnt = parent;
681 follow_mount(&nd->mnt, &nd->dentry);
685 * It's more convoluted than I'd like it to be, but... it's still fairly
686 * small and for now I'd prefer to have fast path as straight as possible.
687 * It _is_ time-critical.
689 static int do_lookup(struct nameidata *nd, struct qstr *name,
690 struct path *path)
692 struct vfsmount *mnt = nd->mnt;
693 struct dentry *dentry = __d_lookup(nd->dentry, name);
695 if (!dentry)
696 goto need_lookup;
697 if (dentry->d_op && dentry->d_op->d_revalidate)
698 goto need_revalidate;
699 done:
700 path->mnt = mnt;
701 path->dentry = dentry;
702 __follow_mount(path);
703 return 0;
705 need_lookup:
706 dentry = real_lookup(nd->dentry, name, nd);
707 if (IS_ERR(dentry))
708 goto fail;
709 goto done;
711 need_revalidate:
712 if (dentry->d_op->d_revalidate(dentry, nd))
713 goto done;
714 if (d_invalidate(dentry))
715 goto done;
716 dput(dentry);
717 goto need_lookup;
719 fail:
720 return PTR_ERR(dentry);
724 * Name resolution.
725 * This is the basic name resolution function, turning a pathname into
726 * the final dentry. We expect 'base' to be positive and a directory.
728 * Returns 0 and nd will have valid dentry and mnt on success.
729 * Returns error and drops reference to input namei data on failure.
731 static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
733 struct path next;
734 struct inode *inode;
735 int err;
736 unsigned int lookup_flags = nd->flags;
738 while (*name=='/')
739 name++;
740 if (!*name)
741 goto return_reval;
743 inode = nd->dentry->d_inode;
744 if (nd->depth)
745 lookup_flags = LOOKUP_FOLLOW;
747 /* At this point we know we have a real path component. */
748 for(;;) {
749 unsigned long hash;
750 struct qstr this;
751 unsigned int c;
753 err = exec_permission_lite(inode, nd);
754 if (err == -EAGAIN) {
755 err = permission(inode, MAY_EXEC, nd);
757 if (err)
758 break;
760 this.name = name;
761 c = *(const unsigned char *)name;
763 hash = init_name_hash();
764 do {
765 name++;
766 hash = partial_name_hash(c, hash);
767 c = *(const unsigned char *)name;
768 } while (c && (c != '/'));
769 this.len = name - (const char *) this.name;
770 this.hash = end_name_hash(hash);
772 /* remove trailing slashes? */
773 if (!c)
774 goto last_component;
775 while (*++name == '/');
776 if (!*name)
777 goto last_with_slashes;
780 * "." and ".." are special - ".." especially so because it has
781 * to be able to know about the current root directory and
782 * parent relationships.
784 if (this.name[0] == '.') switch (this.len) {
785 default:
786 break;
787 case 2:
788 if (this.name[1] != '.')
789 break;
790 follow_dotdot(nd);
791 inode = nd->dentry->d_inode;
792 /* fallthrough */
793 case 1:
794 continue;
797 * See if the low-level filesystem might want
798 * to use its own hash..
800 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
801 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
802 if (err < 0)
803 break;
805 nd->flags |= LOOKUP_CONTINUE;
806 /* This does the actual lookups.. */
807 err = do_lookup(nd, &this, &next);
808 if (err)
809 break;
811 err = -ENOENT;
812 inode = next.dentry->d_inode;
813 if (!inode)
814 goto out_dput;
815 err = -ENOTDIR;
816 if (!inode->i_op)
817 goto out_dput;
819 if (inode->i_op->follow_link) {
820 err = do_follow_link(&next, nd);
821 if (err)
822 goto return_err;
823 err = -ENOENT;
824 inode = nd->dentry->d_inode;
825 if (!inode)
826 break;
827 err = -ENOTDIR;
828 if (!inode->i_op)
829 break;
830 } else
831 path_to_nameidata(&next, nd);
832 err = -ENOTDIR;
833 if (!inode->i_op->lookup)
834 break;
835 continue;
836 /* here ends the main loop */
838 last_with_slashes:
839 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
840 last_component:
841 nd->flags &= ~LOOKUP_CONTINUE;
842 if (lookup_flags & LOOKUP_PARENT)
843 goto lookup_parent;
844 if (this.name[0] == '.') switch (this.len) {
845 default:
846 break;
847 case 2:
848 if (this.name[1] != '.')
849 break;
850 follow_dotdot(nd);
851 inode = nd->dentry->d_inode;
852 /* fallthrough */
853 case 1:
854 goto return_reval;
856 if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
857 err = nd->dentry->d_op->d_hash(nd->dentry, &this);
858 if (err < 0)
859 break;
861 err = do_lookup(nd, &this, &next);
862 if (err)
863 break;
864 inode = next.dentry->d_inode;
865 if ((lookup_flags & LOOKUP_FOLLOW)
866 && inode && inode->i_op && inode->i_op->follow_link) {
867 err = do_follow_link(&next, nd);
868 if (err)
869 goto return_err;
870 inode = nd->dentry->d_inode;
871 } else
872 path_to_nameidata(&next, nd);
873 err = -ENOENT;
874 if (!inode)
875 break;
876 if (lookup_flags & LOOKUP_DIRECTORY) {
877 err = -ENOTDIR;
878 if (!inode->i_op || !inode->i_op->lookup)
879 break;
881 goto return_base;
882 lookup_parent:
883 nd->last = this;
884 nd->last_type = LAST_NORM;
885 if (this.name[0] != '.')
886 goto return_base;
887 if (this.len == 1)
888 nd->last_type = LAST_DOT;
889 else if (this.len == 2 && this.name[1] == '.')
890 nd->last_type = LAST_DOTDOT;
891 else
892 goto return_base;
893 return_reval:
895 * We bypassed the ordinary revalidation routines.
896 * We may need to check the cached dentry for staleness.
898 if (nd->dentry && nd->dentry->d_sb &&
899 (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
900 err = -ESTALE;
901 /* Note: we do not d_invalidate() */
902 if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
903 break;
905 return_base:
906 return 0;
907 out_dput:
908 dput_path(&next, nd);
909 break;
911 path_release(nd);
912 return_err:
913 return err;
917 * Wrapper to retry pathname resolution whenever the underlying
918 * file system returns an ESTALE.
920 * Retry the whole path once, forcing real lookup requests
921 * instead of relying on the dcache.
923 int fastcall link_path_walk(const char *name, struct nameidata *nd)
925 struct nameidata save = *nd;
926 int result;
928 /* make sure the stuff we saved doesn't go away */
929 dget(save.dentry);
930 mntget(save.mnt);
932 result = __link_path_walk(name, nd);
933 if (result == -ESTALE) {
934 *nd = save;
935 dget(nd->dentry);
936 mntget(nd->mnt);
937 nd->flags |= LOOKUP_REVAL;
938 result = __link_path_walk(name, nd);
941 dput(save.dentry);
942 mntput(save.mnt);
944 return result;
947 int fastcall path_walk(const char * name, struct nameidata *nd)
949 current->total_link_count = 0;
950 return link_path_walk(name, nd);
954 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
955 * everything is done. Returns 0 and drops input nd, if lookup failed;
957 static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
959 if (path_walk(name, nd))
960 return 0; /* something went wrong... */
962 if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
963 struct dentry *old_dentry = nd->dentry;
964 struct vfsmount *old_mnt = nd->mnt;
965 struct qstr last = nd->last;
966 int last_type = nd->last_type;
968 * NAME was not found in alternate root or it's a directory. Try to find
969 * it in the normal root:
971 nd->last_type = LAST_ROOT;
972 read_lock(&current->fs->lock);
973 nd->mnt = mntget(current->fs->rootmnt);
974 nd->dentry = dget(current->fs->root);
975 read_unlock(&current->fs->lock);
976 if (path_walk(name, nd) == 0) {
977 if (nd->dentry->d_inode) {
978 dput(old_dentry);
979 mntput(old_mnt);
980 return 1;
982 path_release(nd);
984 nd->dentry = old_dentry;
985 nd->mnt = old_mnt;
986 nd->last = last;
987 nd->last_type = last_type;
989 return 1;
992 void set_fs_altroot(void)
994 char *emul = __emul_prefix();
995 struct nameidata nd;
996 struct vfsmount *mnt = NULL, *oldmnt;
997 struct dentry *dentry = NULL, *olddentry;
998 int err;
1000 if (!emul)
1001 goto set_it;
1002 err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
1003 if (!err) {
1004 mnt = nd.mnt;
1005 dentry = nd.dentry;
1007 set_it:
1008 write_lock(&current->fs->lock);
1009 oldmnt = current->fs->altrootmnt;
1010 olddentry = current->fs->altroot;
1011 current->fs->altrootmnt = mnt;
1012 current->fs->altroot = dentry;
1013 write_unlock(&current->fs->lock);
1014 if (olddentry) {
1015 dput(olddentry);
1016 mntput(oldmnt);
1020 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1021 int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd)
1023 int retval = 0;
1025 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1026 nd->flags = flags;
1027 nd->depth = 0;
1029 read_lock(&current->fs->lock);
1030 if (*name=='/') {
1031 if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
1032 nd->mnt = mntget(current->fs->altrootmnt);
1033 nd->dentry = dget(current->fs->altroot);
1034 read_unlock(&current->fs->lock);
1035 if (__emul_lookup_dentry(name,nd))
1036 goto out; /* found in altroot */
1037 read_lock(&current->fs->lock);
1039 nd->mnt = mntget(current->fs->rootmnt);
1040 nd->dentry = dget(current->fs->root);
1041 } else {
1042 nd->mnt = mntget(current->fs->pwdmnt);
1043 nd->dentry = dget(current->fs->pwd);
1045 read_unlock(&current->fs->lock);
1046 current->total_link_count = 0;
1047 retval = link_path_walk(name, nd);
1048 out:
1049 if (unlikely(current->audit_context
1050 && nd && nd->dentry && nd->dentry->d_inode))
1051 audit_inode(name, nd->dentry->d_inode);
1052 return retval;
1056 * Restricted form of lookup. Doesn't follow links, single-component only,
1057 * needs parent already locked. Doesn't follow mounts.
1058 * SMP-safe.
1060 static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
1062 struct dentry * dentry;
1063 struct inode *inode;
1064 int err;
1066 inode = base->d_inode;
1067 err = permission(inode, MAY_EXEC, nd);
1068 dentry = ERR_PTR(err);
1069 if (err)
1070 goto out;
1073 * See if the low-level filesystem might want
1074 * to use its own hash..
1076 if (base->d_op && base->d_op->d_hash) {
1077 err = base->d_op->d_hash(base, name);
1078 dentry = ERR_PTR(err);
1079 if (err < 0)
1080 goto out;
1083 dentry = cached_lookup(base, name, nd);
1084 if (!dentry) {
1085 struct dentry *new = d_alloc(base, name);
1086 dentry = ERR_PTR(-ENOMEM);
1087 if (!new)
1088 goto out;
1089 dentry = inode->i_op->lookup(inode, new, nd);
1090 if (!dentry)
1091 dentry = new;
1092 else
1093 dput(new);
1095 out:
1096 return dentry;
1099 struct dentry * lookup_hash(struct qstr *name, struct dentry * base)
1101 return __lookup_hash(name, base, NULL);
1104 /* SMP-safe */
1105 struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
1107 unsigned long hash;
1108 struct qstr this;
1109 unsigned int c;
1111 this.name = name;
1112 this.len = len;
1113 if (!len)
1114 goto access;
1116 hash = init_name_hash();
1117 while (len--) {
1118 c = *(const unsigned char *)name++;
1119 if (c == '/' || c == '\0')
1120 goto access;
1121 hash = partial_name_hash(c, hash);
1123 this.hash = end_name_hash(hash);
1125 return lookup_hash(&this, base);
1126 access:
1127 return ERR_PTR(-EACCES);
1131 * namei()
1133 * is used by most simple commands to get the inode of a specified name.
1134 * Open, link etc use their own routines, but this is enough for things
1135 * like 'chmod' etc.
1137 * namei exists in two versions: namei/lnamei. The only difference is
1138 * that namei follows links, while lnamei does not.
1139 * SMP-safe
1141 int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
1143 char *tmp = getname(name);
1144 int err = PTR_ERR(tmp);
1146 if (!IS_ERR(tmp)) {
1147 err = path_lookup(tmp, flags, nd);
1148 putname(tmp);
1150 return err;
1154 * It's inline, so penalty for filesystems that don't use sticky bit is
1155 * minimal.
1157 static inline int check_sticky(struct inode *dir, struct inode *inode)
1159 if (!(dir->i_mode & S_ISVTX))
1160 return 0;
1161 if (inode->i_uid == current->fsuid)
1162 return 0;
1163 if (dir->i_uid == current->fsuid)
1164 return 0;
1165 return !capable(CAP_FOWNER);
1169 * Check whether we can remove a link victim from directory dir, check
1170 * whether the type of victim is right.
1171 * 1. We can't do it if dir is read-only (done in permission())
1172 * 2. We should have write and exec permissions on dir
1173 * 3. We can't remove anything from append-only dir
1174 * 4. We can't do anything with immutable dir (done in permission())
1175 * 5. If the sticky bit on dir is set we should either
1176 * a. be owner of dir, or
1177 * b. be owner of victim, or
1178 * c. have CAP_FOWNER capability
1179 * 6. If the victim is append-only or immutable we can't do antyhing with
1180 * links pointing to it.
1181 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1182 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1183 * 9. We can't remove a root or mountpoint.
1184 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1185 * nfs_async_unlink().
1187 static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1189 int error;
1191 if (!victim->d_inode)
1192 return -ENOENT;
1194 BUG_ON(victim->d_parent->d_inode != dir);
1196 error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
1197 if (error)
1198 return error;
1199 if (IS_APPEND(dir))
1200 return -EPERM;
1201 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1202 IS_IMMUTABLE(victim->d_inode))
1203 return -EPERM;
1204 if (isdir) {
1205 if (!S_ISDIR(victim->d_inode->i_mode))
1206 return -ENOTDIR;
1207 if (IS_ROOT(victim))
1208 return -EBUSY;
1209 } else if (S_ISDIR(victim->d_inode->i_mode))
1210 return -EISDIR;
1211 if (IS_DEADDIR(dir))
1212 return -ENOENT;
1213 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1214 return -EBUSY;
1215 return 0;
1218 /* Check whether we can create an object with dentry child in directory
1219 * dir.
1220 * 1. We can't do it if child already exists (open has special treatment for
1221 * this case, but since we are inlined it's OK)
1222 * 2. We can't do it if dir is read-only (done in permission())
1223 * 3. We should have write and exec permissions on dir
1224 * 4. We can't do it if dir is immutable (done in permission())
1226 static inline int may_create(struct inode *dir, struct dentry *child,
1227 struct nameidata *nd)
1229 if (child->d_inode)
1230 return -EEXIST;
1231 if (IS_DEADDIR(dir))
1232 return -ENOENT;
1233 return permission(dir,MAY_WRITE | MAY_EXEC, nd);
1237 * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
1238 * reasons.
1240 * O_DIRECTORY translates into forcing a directory lookup.
1242 static inline int lookup_flags(unsigned int f)
1244 unsigned long retval = LOOKUP_FOLLOW;
1246 if (f & O_NOFOLLOW)
1247 retval &= ~LOOKUP_FOLLOW;
1249 if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
1250 retval &= ~LOOKUP_FOLLOW;
1252 if (f & O_DIRECTORY)
1253 retval |= LOOKUP_DIRECTORY;
1255 return retval;
1259 * p1 and p2 should be directories on the same fs.
1261 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1263 struct dentry *p;
1265 if (p1 == p2) {
1266 down(&p1->d_inode->i_sem);
1267 return NULL;
1270 down(&p1->d_inode->i_sb->s_vfs_rename_sem);
1272 for (p = p1; p->d_parent != p; p = p->d_parent) {
1273 if (p->d_parent == p2) {
1274 down(&p2->d_inode->i_sem);
1275 down(&p1->d_inode->i_sem);
1276 return p;
1280 for (p = p2; p->d_parent != p; p = p->d_parent) {
1281 if (p->d_parent == p1) {
1282 down(&p1->d_inode->i_sem);
1283 down(&p2->d_inode->i_sem);
1284 return p;
1288 down(&p1->d_inode->i_sem);
1289 down(&p2->d_inode->i_sem);
1290 return NULL;
1293 void unlock_rename(struct dentry *p1, struct dentry *p2)
1295 up(&p1->d_inode->i_sem);
1296 if (p1 != p2) {
1297 up(&p2->d_inode->i_sem);
1298 up(&p1->d_inode->i_sb->s_vfs_rename_sem);
1302 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1303 struct nameidata *nd)
1305 int error = may_create(dir, dentry, nd);
1307 if (error)
1308 return error;
1310 if (!dir->i_op || !dir->i_op->create)
1311 return -EACCES; /* shouldn't it be ENOSYS? */
1312 mode &= S_IALLUGO;
1313 mode |= S_IFREG;
1314 error = security_inode_create(dir, dentry, mode);
1315 if (error)
1316 return error;
1317 DQUOT_INIT(dir);
1318 error = dir->i_op->create(dir, dentry, mode, nd);
1319 if (!error) {
1320 fsnotify_create(dir, dentry->d_name.name);
1321 security_inode_post_create(dir, dentry, mode);
1323 return error;
1326 int may_open(struct nameidata *nd, int acc_mode, int flag)
1328 struct dentry *dentry = nd->dentry;
1329 struct inode *inode = dentry->d_inode;
1330 int error;
1332 if (!inode)
1333 return -ENOENT;
1335 if (S_ISLNK(inode->i_mode))
1336 return -ELOOP;
1338 if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
1339 return -EISDIR;
1341 error = permission(inode, acc_mode, nd);
1342 if (error)
1343 return error;
1346 * FIFO's, sockets and device files are special: they don't
1347 * actually live on the filesystem itself, and as such you
1348 * can write to them even if the filesystem is read-only.
1350 if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
1351 flag &= ~O_TRUNC;
1352 } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
1353 if (nd->mnt->mnt_flags & MNT_NODEV)
1354 return -EACCES;
1356 flag &= ~O_TRUNC;
1357 } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
1358 return -EROFS;
1360 * An append-only file must be opened in append mode for writing.
1362 if (IS_APPEND(inode)) {
1363 if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
1364 return -EPERM;
1365 if (flag & O_TRUNC)
1366 return -EPERM;
1369 /* O_NOATIME can only be set by the owner or superuser */
1370 if (flag & O_NOATIME)
1371 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
1372 return -EPERM;
1375 * Ensure there are no outstanding leases on the file.
1377 error = break_lease(inode, flag);
1378 if (error)
1379 return error;
1381 if (flag & O_TRUNC) {
1382 error = get_write_access(inode);
1383 if (error)
1384 return error;
1387 * Refuse to truncate files with mandatory locks held on them.
1389 error = locks_verify_locked(inode);
1390 if (!error) {
1391 DQUOT_INIT(inode);
1393 error = do_truncate(dentry, 0);
1395 put_write_access(inode);
1396 if (error)
1397 return error;
1398 } else
1399 if (flag & FMODE_WRITE)
1400 DQUOT_INIT(inode);
1402 return 0;
1406 * open_namei()
1408 * namei for open - this is in fact almost the whole open-routine.
1410 * Note that the low bits of "flag" aren't the same as in the open
1411 * system call - they are 00 - no permissions needed
1412 * 01 - read permission needed
1413 * 10 - write permission needed
1414 * 11 - read/write permissions needed
1415 * which is a lot more logical, and also allows the "no perm" needed
1416 * for symlinks (where the permissions are checked later).
1417 * SMP-safe
1419 int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
1421 int acc_mode, error = 0;
1422 struct path path;
1423 struct dentry *dir;
1424 int count = 0;
1426 acc_mode = ACC_MODE(flag);
1428 /* Allow the LSM permission hook to distinguish append
1429 access from general write access. */
1430 if (flag & O_APPEND)
1431 acc_mode |= MAY_APPEND;
1433 /* Fill in the open() intent data */
1434 nd->intent.open.flags = flag;
1435 nd->intent.open.create_mode = mode;
1438 * The simplest case - just a plain lookup.
1440 if (!(flag & O_CREAT)) {
1441 error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd);
1442 if (error)
1443 return error;
1444 goto ok;
1448 * Create - we need to know the parent.
1450 error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd);
1451 if (error)
1452 return error;
1455 * We have the parent and last component. First of all, check
1456 * that we are not asked to creat(2) an obvious directory - that
1457 * will not do.
1459 error = -EISDIR;
1460 if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
1461 goto exit;
1463 dir = nd->dentry;
1464 nd->flags &= ~LOOKUP_PARENT;
1465 down(&dir->d_inode->i_sem);
1466 path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1467 path.mnt = nd->mnt;
1469 do_last:
1470 error = PTR_ERR(path.dentry);
1471 if (IS_ERR(path.dentry)) {
1472 up(&dir->d_inode->i_sem);
1473 goto exit;
1476 /* Negative dentry, just create the file */
1477 if (!path.dentry->d_inode) {
1478 if (!IS_POSIXACL(dir->d_inode))
1479 mode &= ~current->fs->umask;
1480 error = vfs_create(dir->d_inode, path.dentry, mode, nd);
1481 up(&dir->d_inode->i_sem);
1482 dput(nd->dentry);
1483 nd->dentry = path.dentry;
1484 if (error)
1485 goto exit;
1486 /* Don't check for write permission, don't truncate */
1487 acc_mode = 0;
1488 flag &= ~O_TRUNC;
1489 goto ok;
1493 * It already exists.
1495 up(&dir->d_inode->i_sem);
1497 error = -EEXIST;
1498 if (flag & O_EXCL)
1499 goto exit_dput;
1501 if (__follow_mount(&path)) {
1502 error = -ELOOP;
1503 if (flag & O_NOFOLLOW)
1504 goto exit_dput;
1506 error = -ENOENT;
1507 if (!path.dentry->d_inode)
1508 goto exit_dput;
1509 if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
1510 goto do_link;
1512 path_to_nameidata(&path, nd);
1513 error = -EISDIR;
1514 if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
1515 goto exit;
1517 error = may_open(nd, acc_mode, flag);
1518 if (error)
1519 goto exit;
1520 return 0;
1522 exit_dput:
1523 dput_path(&path, nd);
1524 exit:
1525 path_release(nd);
1526 return error;
1528 do_link:
1529 error = -ELOOP;
1530 if (flag & O_NOFOLLOW)
1531 goto exit_dput;
1533 * This is subtle. Instead of calling do_follow_link() we do the
1534 * thing by hands. The reason is that this way we have zero link_count
1535 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1536 * After that we have the parent and last component, i.e.
1537 * we are in the same situation as after the first path_walk().
1538 * Well, almost - if the last component is normal we get its copy
1539 * stored in nd->last.name and we will have to putname() it when we
1540 * are done. Procfs-like symlinks just set LAST_BIND.
1542 nd->flags |= LOOKUP_PARENT;
1543 error = security_inode_follow_link(path.dentry, nd);
1544 if (error)
1545 goto exit_dput;
1546 error = __do_follow_link(&path, nd);
1547 if (error)
1548 return error;
1549 nd->flags &= ~LOOKUP_PARENT;
1550 if (nd->last_type == LAST_BIND)
1551 goto ok;
1552 error = -EISDIR;
1553 if (nd->last_type != LAST_NORM)
1554 goto exit;
1555 if (nd->last.name[nd->last.len]) {
1556 putname(nd->last.name);
1557 goto exit;
1559 error = -ELOOP;
1560 if (count++==32) {
1561 putname(nd->last.name);
1562 goto exit;
1564 dir = nd->dentry;
1565 down(&dir->d_inode->i_sem);
1566 path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
1567 path.mnt = nd->mnt;
1568 putname(nd->last.name);
1569 goto do_last;
1573 * lookup_create - lookup a dentry, creating it if it doesn't exist
1574 * @nd: nameidata info
1575 * @is_dir: directory flag
1577 * Simple function to lookup and return a dentry and create it
1578 * if it doesn't exist. Is SMP-safe.
1580 * Returns with nd->dentry->d_inode->i_sem locked.
1582 struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1584 struct dentry *dentry = ERR_PTR(-EEXIST);
1586 down(&nd->dentry->d_inode->i_sem);
1588 * Yucky last component or no last component at all?
1589 * (foo/., foo/.., /////)
1591 if (nd->last_type != LAST_NORM)
1592 goto fail;
1593 nd->flags &= ~LOOKUP_PARENT;
1596 * Do the final lookup.
1598 dentry = lookup_hash(&nd->last, nd->dentry);
1599 if (IS_ERR(dentry))
1600 goto fail;
1603 * Special case - lookup gave negative, but... we had foo/bar/
1604 * From the vfs_mknod() POV we just have a negative dentry -
1605 * all is fine. Let's be bastards - you had / on the end, you've
1606 * been asking for (non-existent) directory. -ENOENT for you.
1608 if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
1609 goto enoent;
1610 return dentry;
1611 enoent:
1612 dput(dentry);
1613 dentry = ERR_PTR(-ENOENT);
1614 fail:
1615 return dentry;
1617 EXPORT_SYMBOL_GPL(lookup_create);
1619 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1621 int error = may_create(dir, dentry, NULL);
1623 if (error)
1624 return error;
1626 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1627 return -EPERM;
1629 if (!dir->i_op || !dir->i_op->mknod)
1630 return -EPERM;
1632 error = security_inode_mknod(dir, dentry, mode, dev);
1633 if (error)
1634 return error;
1636 DQUOT_INIT(dir);
1637 error = dir->i_op->mknod(dir, dentry, mode, dev);
1638 if (!error) {
1639 fsnotify_create(dir, dentry->d_name.name);
1640 security_inode_post_mknod(dir, dentry, mode, dev);
1642 return error;
1645 asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev)
1647 int error = 0;
1648 char * tmp;
1649 struct dentry * dentry;
1650 struct nameidata nd;
1652 if (S_ISDIR(mode))
1653 return -EPERM;
1654 tmp = getname(filename);
1655 if (IS_ERR(tmp))
1656 return PTR_ERR(tmp);
1658 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1659 if (error)
1660 goto out;
1661 dentry = lookup_create(&nd, 0);
1662 error = PTR_ERR(dentry);
1664 if (!IS_POSIXACL(nd.dentry->d_inode))
1665 mode &= ~current->fs->umask;
1666 if (!IS_ERR(dentry)) {
1667 switch (mode & S_IFMT) {
1668 case 0: case S_IFREG:
1669 error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
1670 break;
1671 case S_IFCHR: case S_IFBLK:
1672 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
1673 new_decode_dev(dev));
1674 break;
1675 case S_IFIFO: case S_IFSOCK:
1676 error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
1677 break;
1678 case S_IFDIR:
1679 error = -EPERM;
1680 break;
1681 default:
1682 error = -EINVAL;
1684 dput(dentry);
1686 up(&nd.dentry->d_inode->i_sem);
1687 path_release(&nd);
1688 out:
1689 putname(tmp);
1691 return error;
1694 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1696 int error = may_create(dir, dentry, NULL);
1698 if (error)
1699 return error;
1701 if (!dir->i_op || !dir->i_op->mkdir)
1702 return -EPERM;
1704 mode &= (S_IRWXUGO|S_ISVTX);
1705 error = security_inode_mkdir(dir, dentry, mode);
1706 if (error)
1707 return error;
1709 DQUOT_INIT(dir);
1710 error = dir->i_op->mkdir(dir, dentry, mode);
1711 if (!error) {
1712 fsnotify_mkdir(dir, dentry->d_name.name);
1713 security_inode_post_mkdir(dir,dentry, mode);
1715 return error;
1718 asmlinkage long sys_mkdir(const char __user * pathname, int mode)
1720 int error = 0;
1721 char * tmp;
1723 tmp = getname(pathname);
1724 error = PTR_ERR(tmp);
1725 if (!IS_ERR(tmp)) {
1726 struct dentry *dentry;
1727 struct nameidata nd;
1729 error = path_lookup(tmp, LOOKUP_PARENT, &nd);
1730 if (error)
1731 goto out;
1732 dentry = lookup_create(&nd, 1);
1733 error = PTR_ERR(dentry);
1734 if (!IS_ERR(dentry)) {
1735 if (!IS_POSIXACL(nd.dentry->d_inode))
1736 mode &= ~current->fs->umask;
1737 error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
1738 dput(dentry);
1740 up(&nd.dentry->d_inode->i_sem);
1741 path_release(&nd);
1742 out:
1743 putname(tmp);
1746 return error;
1750 * We try to drop the dentry early: we should have
1751 * a usage count of 2 if we're the only user of this
1752 * dentry, and if that is true (possibly after pruning
1753 * the dcache), then we drop the dentry now.
1755 * A low-level filesystem can, if it choses, legally
1756 * do a
1758 * if (!d_unhashed(dentry))
1759 * return -EBUSY;
1761 * if it cannot handle the case of removing a directory
1762 * that is still in use by something else..
1764 void dentry_unhash(struct dentry *dentry)
1766 dget(dentry);
1767 if (atomic_read(&dentry->d_count))
1768 shrink_dcache_parent(dentry);
1769 spin_lock(&dcache_lock);
1770 spin_lock(&dentry->d_lock);
1771 if (atomic_read(&dentry->d_count) == 2)
1772 __d_drop(dentry);
1773 spin_unlock(&dentry->d_lock);
1774 spin_unlock(&dcache_lock);
1777 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
1779 int error = may_delete(dir, dentry, 1);
1781 if (error)
1782 return error;
1784 if (!dir->i_op || !dir->i_op->rmdir)
1785 return -EPERM;
1787 DQUOT_INIT(dir);
1789 down(&dentry->d_inode->i_sem);
1790 dentry_unhash(dentry);
1791 if (d_mountpoint(dentry))
1792 error = -EBUSY;
1793 else {
1794 error = security_inode_rmdir(dir, dentry);
1795 if (!error) {
1796 error = dir->i_op->rmdir(dir, dentry);
1797 if (!error)
1798 dentry->d_inode->i_flags |= S_DEAD;
1801 up(&dentry->d_inode->i_sem);
1802 if (!error) {
1803 d_delete(dentry);
1805 dput(dentry);
1807 return error;
1810 asmlinkage long sys_rmdir(const char __user * pathname)
1812 int error = 0;
1813 char * name;
1814 struct dentry *dentry;
1815 struct nameidata nd;
1817 name = getname(pathname);
1818 if(IS_ERR(name))
1819 return PTR_ERR(name);
1821 error = path_lookup(name, LOOKUP_PARENT, &nd);
1822 if (error)
1823 goto exit;
1825 switch(nd.last_type) {
1826 case LAST_DOTDOT:
1827 error = -ENOTEMPTY;
1828 goto exit1;
1829 case LAST_DOT:
1830 error = -EINVAL;
1831 goto exit1;
1832 case LAST_ROOT:
1833 error = -EBUSY;
1834 goto exit1;
1836 down(&nd.dentry->d_inode->i_sem);
1837 dentry = lookup_hash(&nd.last, nd.dentry);
1838 error = PTR_ERR(dentry);
1839 if (!IS_ERR(dentry)) {
1840 error = vfs_rmdir(nd.dentry->d_inode, dentry);
1841 dput(dentry);
1843 up(&nd.dentry->d_inode->i_sem);
1844 exit1:
1845 path_release(&nd);
1846 exit:
1847 putname(name);
1848 return error;
1851 int vfs_unlink(struct inode *dir, struct dentry *dentry)
1853 int error = may_delete(dir, dentry, 0);
1855 if (error)
1856 return error;
1858 if (!dir->i_op || !dir->i_op->unlink)
1859 return -EPERM;
1861 DQUOT_INIT(dir);
1863 down(&dentry->d_inode->i_sem);
1864 if (d_mountpoint(dentry))
1865 error = -EBUSY;
1866 else {
1867 error = security_inode_unlink(dir, dentry);
1868 if (!error)
1869 error = dir->i_op->unlink(dir, dentry);
1871 up(&dentry->d_inode->i_sem);
1873 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
1874 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
1875 d_delete(dentry);
1878 return error;
1882 * Make sure that the actual truncation of the file will occur outside its
1883 * directory's i_sem. Truncate can take a long time if there is a lot of
1884 * writeout happening, and we don't want to prevent access to the directory
1885 * while waiting on the I/O.
1887 asmlinkage long sys_unlink(const char __user * pathname)
1889 int error = 0;
1890 char * name;
1891 struct dentry *dentry;
1892 struct nameidata nd;
1893 struct inode *inode = NULL;
1895 name = getname(pathname);
1896 if(IS_ERR(name))
1897 return PTR_ERR(name);
1899 error = path_lookup(name, LOOKUP_PARENT, &nd);
1900 if (error)
1901 goto exit;
1902 error = -EISDIR;
1903 if (nd.last_type != LAST_NORM)
1904 goto exit1;
1905 down(&nd.dentry->d_inode->i_sem);
1906 dentry = lookup_hash(&nd.last, nd.dentry);
1907 error = PTR_ERR(dentry);
1908 if (!IS_ERR(dentry)) {
1909 /* Why not before? Because we want correct error value */
1910 if (nd.last.name[nd.last.len])
1911 goto slashes;
1912 inode = dentry->d_inode;
1913 if (inode)
1914 atomic_inc(&inode->i_count);
1915 error = vfs_unlink(nd.dentry->d_inode, dentry);
1916 exit2:
1917 dput(dentry);
1919 up(&nd.dentry->d_inode->i_sem);
1920 if (inode)
1921 iput(inode); /* truncate the inode here */
1922 exit1:
1923 path_release(&nd);
1924 exit:
1925 putname(name);
1926 return error;
1928 slashes:
1929 error = !dentry->d_inode ? -ENOENT :
1930 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
1931 goto exit2;
1934 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
1936 int error = may_create(dir, dentry, NULL);
1938 if (error)
1939 return error;
1941 if (!dir->i_op || !dir->i_op->symlink)
1942 return -EPERM;
1944 error = security_inode_symlink(dir, dentry, oldname);
1945 if (error)
1946 return error;
1948 DQUOT_INIT(dir);
1949 error = dir->i_op->symlink(dir, dentry, oldname);
1950 if (!error) {
1951 fsnotify_create(dir, dentry->d_name.name);
1952 security_inode_post_symlink(dir, dentry, oldname);
1954 return error;
1957 asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname)
1959 int error = 0;
1960 char * from;
1961 char * to;
1963 from = getname(oldname);
1964 if(IS_ERR(from))
1965 return PTR_ERR(from);
1966 to = getname(newname);
1967 error = PTR_ERR(to);
1968 if (!IS_ERR(to)) {
1969 struct dentry *dentry;
1970 struct nameidata nd;
1972 error = path_lookup(to, LOOKUP_PARENT, &nd);
1973 if (error)
1974 goto out;
1975 dentry = lookup_create(&nd, 0);
1976 error = PTR_ERR(dentry);
1977 if (!IS_ERR(dentry)) {
1978 error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
1979 dput(dentry);
1981 up(&nd.dentry->d_inode->i_sem);
1982 path_release(&nd);
1983 out:
1984 putname(to);
1986 putname(from);
1987 return error;
1990 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
1992 struct inode *inode = old_dentry->d_inode;
1993 int error;
1995 if (!inode)
1996 return -ENOENT;
1998 error = may_create(dir, new_dentry, NULL);
1999 if (error)
2000 return error;
2002 if (dir->i_sb != inode->i_sb)
2003 return -EXDEV;
2006 * A link to an append-only or immutable file cannot be created.
2008 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2009 return -EPERM;
2010 if (!dir->i_op || !dir->i_op->link)
2011 return -EPERM;
2012 if (S_ISDIR(old_dentry->d_inode->i_mode))
2013 return -EPERM;
2015 error = security_inode_link(old_dentry, dir, new_dentry);
2016 if (error)
2017 return error;
2019 down(&old_dentry->d_inode->i_sem);
2020 DQUOT_INIT(dir);
2021 error = dir->i_op->link(old_dentry, dir, new_dentry);
2022 up(&old_dentry->d_inode->i_sem);
2023 if (!error) {
2024 fsnotify_create(dir, new_dentry->d_name.name);
2025 security_inode_post_link(old_dentry, dir, new_dentry);
2027 return error;
2031 * Hardlinks are often used in delicate situations. We avoid
2032 * security-related surprises by not following symlinks on the
2033 * newname. --KAB
2035 * We don't follow them on the oldname either to be compatible
2036 * with linux 2.0, and to avoid hard-linking to directories
2037 * and other special files. --ADM
2039 asmlinkage long sys_link(const char __user * oldname, const char __user * newname)
2041 struct dentry *new_dentry;
2042 struct nameidata nd, old_nd;
2043 int error;
2044 char * to;
2046 to = getname(newname);
2047 if (IS_ERR(to))
2048 return PTR_ERR(to);
2050 error = __user_walk(oldname, 0, &old_nd);
2051 if (error)
2052 goto exit;
2053 error = path_lookup(to, LOOKUP_PARENT, &nd);
2054 if (error)
2055 goto out;
2056 error = -EXDEV;
2057 if (old_nd.mnt != nd.mnt)
2058 goto out_release;
2059 new_dentry = lookup_create(&nd, 0);
2060 error = PTR_ERR(new_dentry);
2061 if (!IS_ERR(new_dentry)) {
2062 error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
2063 dput(new_dentry);
2065 up(&nd.dentry->d_inode->i_sem);
2066 out_release:
2067 path_release(&nd);
2068 out:
2069 path_release(&old_nd);
2070 exit:
2071 putname(to);
2073 return error;
2077 * The worst of all namespace operations - renaming directory. "Perverted"
2078 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2079 * Problems:
2080 * a) we can get into loop creation. Check is done in is_subdir().
2081 * b) race potential - two innocent renames can create a loop together.
2082 * That's where 4.4 screws up. Current fix: serialization on
2083 * sb->s_vfs_rename_sem. We might be more accurate, but that's another
2084 * story.
2085 * c) we have to lock _three_ objects - parents and victim (if it exists).
2086 * And that - after we got ->i_sem on parents (until then we don't know
2087 * whether the target exists). Solution: try to be smart with locking
2088 * order for inodes. We rely on the fact that tree topology may change
2089 * only under ->s_vfs_rename_sem _and_ that parent of the object we
2090 * move will be locked. Thus we can rank directories by the tree
2091 * (ancestors first) and rank all non-directories after them.
2092 * That works since everybody except rename does "lock parent, lookup,
2093 * lock child" and rename is under ->s_vfs_rename_sem.
2094 * HOWEVER, it relies on the assumption that any object with ->lookup()
2095 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2096 * we'd better make sure that there's no link(2) for them.
2097 * d) some filesystems don't support opened-but-unlinked directories,
2098 * either because of layout or because they are not ready to deal with
2099 * all cases correctly. The latter will be fixed (taking this sort of
2100 * stuff into VFS), but the former is not going away. Solution: the same
2101 * trick as in rmdir().
2102 * e) conversion from fhandle to dentry may come in the wrong moment - when
2103 * we are removing the target. Solution: we will have to grab ->i_sem
2104 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2105 * ->i_sem on parents, which works but leads to some truely excessive
2106 * locking].
2108 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2109 struct inode *new_dir, struct dentry *new_dentry)
2111 int error = 0;
2112 struct inode *target;
2115 * If we are going to change the parent - check write permissions,
2116 * we'll need to flip '..'.
2118 if (new_dir != old_dir) {
2119 error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
2120 if (error)
2121 return error;
2124 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2125 if (error)
2126 return error;
2128 target = new_dentry->d_inode;
2129 if (target) {
2130 down(&target->i_sem);
2131 dentry_unhash(new_dentry);
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 (target) {
2138 if (!error)
2139 target->i_flags |= S_DEAD;
2140 up(&target->i_sem);
2141 if (d_unhashed(new_dentry))
2142 d_rehash(new_dentry);
2143 dput(new_dentry);
2145 if (!error) {
2146 d_move(old_dentry,new_dentry);
2147 security_inode_post_rename(old_dir, old_dentry,
2148 new_dir, new_dentry);
2150 return error;
2153 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2154 struct inode *new_dir, struct dentry *new_dentry)
2156 struct inode *target;
2157 int error;
2159 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2160 if (error)
2161 return error;
2163 dget(new_dentry);
2164 target = new_dentry->d_inode;
2165 if (target)
2166 down(&target->i_sem);
2167 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2168 error = -EBUSY;
2169 else
2170 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2171 if (!error) {
2172 /* The following d_move() should become unconditional */
2173 if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME))
2174 d_move(old_dentry, new_dentry);
2175 security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry);
2177 if (target)
2178 up(&target->i_sem);
2179 dput(new_dentry);
2180 return error;
2183 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2184 struct inode *new_dir, struct dentry *new_dentry)
2186 int error;
2187 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2188 const char *old_name;
2190 if (old_dentry->d_inode == new_dentry->d_inode)
2191 return 0;
2193 error = may_delete(old_dir, old_dentry, is_dir);
2194 if (error)
2195 return error;
2197 if (!new_dentry->d_inode)
2198 error = may_create(new_dir, new_dentry, NULL);
2199 else
2200 error = may_delete(new_dir, new_dentry, is_dir);
2201 if (error)
2202 return error;
2204 if (!old_dir->i_op || !old_dir->i_op->rename)
2205 return -EPERM;
2207 DQUOT_INIT(old_dir);
2208 DQUOT_INIT(new_dir);
2210 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
2212 if (is_dir)
2213 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2214 else
2215 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
2216 if (!error) {
2217 const char *new_name = old_dentry->d_name.name;
2218 fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
2219 new_dentry->d_inode, old_dentry->d_inode);
2221 fsnotify_oldname_free(old_name);
2223 return error;
2226 static inline int do_rename(const char * oldname, const char * newname)
2228 int error = 0;
2229 struct dentry * old_dir, * new_dir;
2230 struct dentry * old_dentry, *new_dentry;
2231 struct dentry * trap;
2232 struct nameidata oldnd, newnd;
2234 error = path_lookup(oldname, LOOKUP_PARENT, &oldnd);
2235 if (error)
2236 goto exit;
2238 error = path_lookup(newname, LOOKUP_PARENT, &newnd);
2239 if (error)
2240 goto exit1;
2242 error = -EXDEV;
2243 if (oldnd.mnt != newnd.mnt)
2244 goto exit2;
2246 old_dir = oldnd.dentry;
2247 error = -EBUSY;
2248 if (oldnd.last_type != LAST_NORM)
2249 goto exit2;
2251 new_dir = newnd.dentry;
2252 if (newnd.last_type != LAST_NORM)
2253 goto exit2;
2255 trap = lock_rename(new_dir, old_dir);
2257 old_dentry = lookup_hash(&oldnd.last, old_dir);
2258 error = PTR_ERR(old_dentry);
2259 if (IS_ERR(old_dentry))
2260 goto exit3;
2261 /* source must exist */
2262 error = -ENOENT;
2263 if (!old_dentry->d_inode)
2264 goto exit4;
2265 /* unless the source is a directory trailing slashes give -ENOTDIR */
2266 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2267 error = -ENOTDIR;
2268 if (oldnd.last.name[oldnd.last.len])
2269 goto exit4;
2270 if (newnd.last.name[newnd.last.len])
2271 goto exit4;
2273 /* source should not be ancestor of target */
2274 error = -EINVAL;
2275 if (old_dentry == trap)
2276 goto exit4;
2277 new_dentry = lookup_hash(&newnd.last, new_dir);
2278 error = PTR_ERR(new_dentry);
2279 if (IS_ERR(new_dentry))
2280 goto exit4;
2281 /* target should not be an ancestor of source */
2282 error = -ENOTEMPTY;
2283 if (new_dentry == trap)
2284 goto exit5;
2286 error = vfs_rename(old_dir->d_inode, old_dentry,
2287 new_dir->d_inode, new_dentry);
2288 exit5:
2289 dput(new_dentry);
2290 exit4:
2291 dput(old_dentry);
2292 exit3:
2293 unlock_rename(new_dir, old_dir);
2294 exit2:
2295 path_release(&newnd);
2296 exit1:
2297 path_release(&oldnd);
2298 exit:
2299 return error;
2302 asmlinkage long sys_rename(const char __user * oldname, const char __user * newname)
2304 int error;
2305 char * from;
2306 char * to;
2308 from = getname(oldname);
2309 if(IS_ERR(from))
2310 return PTR_ERR(from);
2311 to = getname(newname);
2312 error = PTR_ERR(to);
2313 if (!IS_ERR(to)) {
2314 error = do_rename(from,to);
2315 putname(to);
2317 putname(from);
2318 return error;
2321 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2323 int len;
2325 len = PTR_ERR(link);
2326 if (IS_ERR(link))
2327 goto out;
2329 len = strlen(link);
2330 if (len > (unsigned) buflen)
2331 len = buflen;
2332 if (copy_to_user(buffer, link, len))
2333 len = -EFAULT;
2334 out:
2335 return len;
2339 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2340 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2341 * using) it for any given inode is up to filesystem.
2343 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2345 struct nameidata nd;
2346 void *cookie;
2348 nd.depth = 0;
2349 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
2350 if (!IS_ERR(cookie)) {
2351 int res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2352 if (dentry->d_inode->i_op->put_link)
2353 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
2354 cookie = ERR_PTR(res);
2356 return PTR_ERR(cookie);
2359 int vfs_follow_link(struct nameidata *nd, const char *link)
2361 return __vfs_follow_link(nd, link);
2364 /* get the link contents into pagecache */
2365 static char *page_getlink(struct dentry * dentry, struct page **ppage)
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);
2379 async_fail:
2380 page_cache_release(page);
2381 return ERR_PTR(-EIO);
2383 sync_fail:
2384 return (char*)page;
2387 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
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);
2396 return res;
2399 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
2401 struct page *page = NULL;
2402 nd_set_link(nd, page_getlink(dentry, &page));
2403 return page;
2406 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2408 struct page *page = cookie;
2410 if (page) {
2411 kunmap(page);
2412 page_cache_release(page);
2416 int page_symlink(struct inode *inode, const char *symname, int len)
2418 struct address_space *mapping = inode->i_mapping;
2419 struct page *page = grab_cache_page(mapping, 0);
2420 int err = -ENOMEM;
2421 char *kaddr;
2423 if (!page)
2424 goto fail;
2425 err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
2426 if (err)
2427 goto fail_map;
2428 kaddr = kmap_atomic(page, KM_USER0);
2429 memcpy(kaddr, symname, len-1);
2430 kunmap_atomic(kaddr, KM_USER0);
2431 mapping->a_ops->commit_write(NULL, page, 0, len-1);
2433 * Notice that we are _not_ going to block here - end of page is
2434 * unmapped, so this will only try to map the rest of page, see
2435 * that it is unmapped (typically even will not look into inode -
2436 * ->i_size will be enough for everything) and zero it out.
2437 * OTOH it's obviously correct and should make the page up-to-date.
2439 if (!PageUptodate(page)) {
2440 err = mapping->a_ops->readpage(NULL, page);
2441 wait_on_page_locked(page);
2442 } else {
2443 unlock_page(page);
2445 page_cache_release(page);
2446 if (err < 0)
2447 goto fail;
2448 mark_inode_dirty(inode);
2449 return 0;
2450 fail_map:
2451 unlock_page(page);
2452 page_cache_release(page);
2453 fail:
2454 return err;
2457 struct inode_operations page_symlink_inode_operations = {
2458 .readlink = generic_readlink,
2459 .follow_link = page_follow_link_light,
2460 .put_link = page_put_link,
2463 EXPORT_SYMBOL(__user_walk);
2464 EXPORT_SYMBOL(follow_down);
2465 EXPORT_SYMBOL(follow_up);
2466 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2467 EXPORT_SYMBOL(getname);
2468 EXPORT_SYMBOL(lock_rename);
2469 EXPORT_SYMBOL(lookup_hash);
2470 EXPORT_SYMBOL(lookup_one_len);
2471 EXPORT_SYMBOL(page_follow_link_light);
2472 EXPORT_SYMBOL(page_put_link);
2473 EXPORT_SYMBOL(page_readlink);
2474 EXPORT_SYMBOL(page_symlink);
2475 EXPORT_SYMBOL(page_symlink_inode_operations);
2476 EXPORT_SYMBOL(path_lookup);
2477 EXPORT_SYMBOL(path_release);
2478 EXPORT_SYMBOL(path_walk);
2479 EXPORT_SYMBOL(permission);
2480 EXPORT_SYMBOL(unlock_rename);
2481 EXPORT_SYMBOL(vfs_create);
2482 EXPORT_SYMBOL(vfs_follow_link);
2483 EXPORT_SYMBOL(vfs_link);
2484 EXPORT_SYMBOL(vfs_mkdir);
2485 EXPORT_SYMBOL(vfs_mknod);
2486 EXPORT_SYMBOL(generic_permission);
2487 EXPORT_SYMBOL(vfs_readlink);
2488 EXPORT_SYMBOL(vfs_rename);
2489 EXPORT_SYMBOL(vfs_rmdir);
2490 EXPORT_SYMBOL(vfs_symlink);
2491 EXPORT_SYMBOL(vfs_unlink);
2492 EXPORT_SYMBOL(dentry_unhash);
2493 EXPORT_SYMBOL(generic_readlink);