2 * fs/kernfs/dir.c - kernfs directory implementation
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
8 * This file is released under the GPLv2.
11 #include <linux/sched.h>
13 #include <linux/namei.h>
14 #include <linux/idr.h>
15 #include <linux/slab.h>
16 #include <linux/security.h>
17 #include <linux/hash.h>
19 #include "kernfs-internal.h"
21 DEFINE_MUTEX(kernfs_mutex
);
22 static DEFINE_SPINLOCK(kernfs_rename_lock
); /* kn->parent and ->name */
23 static char kernfs_pr_cont_buf
[PATH_MAX
]; /* protected by rename_lock */
25 #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
27 static bool kernfs_active(struct kernfs_node
*kn
)
29 lockdep_assert_held(&kernfs_mutex
);
30 return atomic_read(&kn
->active
) >= 0;
33 static bool kernfs_lockdep(struct kernfs_node
*kn
)
35 #ifdef CONFIG_DEBUG_LOCK_ALLOC
36 return kn
->flags
& KERNFS_LOCKDEP
;
42 static int kernfs_name_locked(struct kernfs_node
*kn
, char *buf
, size_t buflen
)
44 return strlcpy(buf
, kn
->parent
? kn
->name
: "/", buflen
);
47 static char * __must_check
kernfs_path_locked(struct kernfs_node
*kn
, char *buf
,
50 char *p
= buf
+ buflen
;
56 len
= strlen(kn
->name
);
57 if (p
- buf
< len
+ 1) {
63 memcpy(p
, kn
->name
, len
);
66 } while (kn
&& kn
->parent
);
72 * kernfs_name - obtain the name of a given node
73 * @kn: kernfs_node of interest
74 * @buf: buffer to copy @kn's name into
75 * @buflen: size of @buf
77 * Copies the name of @kn into @buf of @buflen bytes. The behavior is
78 * similar to strlcpy(). It returns the length of @kn's name and if @buf
79 * isn't long enough, it's filled upto @buflen-1 and nul terminated.
81 * This function can be called from any context.
83 int kernfs_name(struct kernfs_node
*kn
, char *buf
, size_t buflen
)
88 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
89 ret
= kernfs_name_locked(kn
, buf
, buflen
);
90 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
95 * kernfs_path - build full path of a given node
96 * @kn: kernfs_node of interest
97 * @buf: buffer to copy @kn's name into
98 * @buflen: size of @buf
100 * Builds and returns the full path of @kn in @buf of @buflen bytes. The
101 * path is built from the end of @buf so the returned pointer usually
102 * doesn't match @buf. If @buf isn't long enough, @buf is nul terminated
103 * and %NULL is returned.
105 char *kernfs_path(struct kernfs_node
*kn
, char *buf
, size_t buflen
)
110 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
111 p
= kernfs_path_locked(kn
, buf
, buflen
);
112 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
117 * pr_cont_kernfs_name - pr_cont name of a kernfs_node
118 * @kn: kernfs_node of interest
120 * This function can be called from any context.
122 void pr_cont_kernfs_name(struct kernfs_node
*kn
)
126 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
128 kernfs_name_locked(kn
, kernfs_pr_cont_buf
, sizeof(kernfs_pr_cont_buf
));
129 pr_cont("%s", kernfs_pr_cont_buf
);
131 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
135 * pr_cont_kernfs_path - pr_cont path of a kernfs_node
136 * @kn: kernfs_node of interest
138 * This function can be called from any context.
140 void pr_cont_kernfs_path(struct kernfs_node
*kn
)
145 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
147 p
= kernfs_path_locked(kn
, kernfs_pr_cont_buf
,
148 sizeof(kernfs_pr_cont_buf
));
152 pr_cont("<name too long>");
154 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
158 * kernfs_get_parent - determine the parent node and pin it
159 * @kn: kernfs_node of interest
161 * Determines @kn's parent, pins and returns it. This function can be
162 * called from any context.
164 struct kernfs_node
*kernfs_get_parent(struct kernfs_node
*kn
)
166 struct kernfs_node
*parent
;
169 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
172 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
179 * @name: Null terminated string to hash
180 * @ns: Namespace tag to hash
182 * Returns 31 bit hash of ns + name (so it fits in an off_t )
184 static unsigned int kernfs_name_hash(const char *name
, const void *ns
)
186 unsigned long hash
= init_name_hash();
187 unsigned int len
= strlen(name
);
189 hash
= partial_name_hash(*name
++, hash
);
190 hash
= (end_name_hash(hash
) ^ hash_ptr((void *)ns
, 31));
192 /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
200 static int kernfs_name_compare(unsigned int hash
, const char *name
,
201 const void *ns
, const struct kernfs_node
*kn
)
203 if (hash
!= kn
->hash
)
204 return hash
- kn
->hash
;
207 return strcmp(name
, kn
->name
);
210 static int kernfs_sd_compare(const struct kernfs_node
*left
,
211 const struct kernfs_node
*right
)
213 return kernfs_name_compare(left
->hash
, left
->name
, left
->ns
, right
);
217 * kernfs_link_sibling - link kernfs_node into sibling rbtree
218 * @kn: kernfs_node of interest
220 * Link @kn into its sibling rbtree which starts from
221 * @kn->parent->dir.children.
224 * mutex_lock(kernfs_mutex)
227 * 0 on susccess -EEXIST on failure.
229 static int kernfs_link_sibling(struct kernfs_node
*kn
)
231 struct rb_node
**node
= &kn
->parent
->dir
.children
.rb_node
;
232 struct rb_node
*parent
= NULL
;
234 if (kernfs_type(kn
) == KERNFS_DIR
)
235 kn
->parent
->dir
.subdirs
++;
238 struct kernfs_node
*pos
;
241 pos
= rb_to_kn(*node
);
243 result
= kernfs_sd_compare(kn
, pos
);
245 node
= &pos
->rb
.rb_left
;
247 node
= &pos
->rb
.rb_right
;
251 /* add new node and rebalance the tree */
252 rb_link_node(&kn
->rb
, parent
, node
);
253 rb_insert_color(&kn
->rb
, &kn
->parent
->dir
.children
);
258 * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
259 * @kn: kernfs_node of interest
261 * Try to unlink @kn from its sibling rbtree which starts from
262 * kn->parent->dir.children. Returns %true if @kn was actually
263 * removed, %false if @kn wasn't on the rbtree.
266 * mutex_lock(kernfs_mutex)
268 static bool kernfs_unlink_sibling(struct kernfs_node
*kn
)
270 if (RB_EMPTY_NODE(&kn
->rb
))
273 if (kernfs_type(kn
) == KERNFS_DIR
)
274 kn
->parent
->dir
.subdirs
--;
276 rb_erase(&kn
->rb
, &kn
->parent
->dir
.children
);
277 RB_CLEAR_NODE(&kn
->rb
);
282 * kernfs_get_active - get an active reference to kernfs_node
283 * @kn: kernfs_node to get an active reference to
285 * Get an active reference of @kn. This function is noop if @kn
289 * Pointer to @kn on success, NULL on failure.
291 struct kernfs_node
*kernfs_get_active(struct kernfs_node
*kn
)
296 if (!atomic_inc_unless_negative(&kn
->active
))
299 if (kernfs_lockdep(kn
))
300 rwsem_acquire_read(&kn
->dep_map
, 0, 1, _RET_IP_
);
305 * kernfs_put_active - put an active reference to kernfs_node
306 * @kn: kernfs_node to put an active reference to
308 * Put an active reference to @kn. This function is noop if @kn
311 void kernfs_put_active(struct kernfs_node
*kn
)
313 struct kernfs_root
*root
= kernfs_root(kn
);
319 if (kernfs_lockdep(kn
))
320 rwsem_release(&kn
->dep_map
, 1, _RET_IP_
);
321 v
= atomic_dec_return(&kn
->active
);
322 if (likely(v
!= KN_DEACTIVATED_BIAS
))
325 wake_up_all(&root
->deactivate_waitq
);
329 * kernfs_drain - drain kernfs_node
330 * @kn: kernfs_node to drain
332 * Drain existing usages and nuke all existing mmaps of @kn. Mutiple
333 * removers may invoke this function concurrently on @kn and all will
334 * return after draining is complete.
336 static void kernfs_drain(struct kernfs_node
*kn
)
337 __releases(&kernfs_mutex
) __acquires(&kernfs_mutex
)
339 struct kernfs_root
*root
= kernfs_root(kn
);
341 lockdep_assert_held(&kernfs_mutex
);
342 WARN_ON_ONCE(kernfs_active(kn
));
344 mutex_unlock(&kernfs_mutex
);
346 if (kernfs_lockdep(kn
)) {
347 rwsem_acquire(&kn
->dep_map
, 0, 0, _RET_IP_
);
348 if (atomic_read(&kn
->active
) != KN_DEACTIVATED_BIAS
)
349 lock_contended(&kn
->dep_map
, _RET_IP_
);
352 /* but everyone should wait for draining */
353 wait_event(root
->deactivate_waitq
,
354 atomic_read(&kn
->active
) == KN_DEACTIVATED_BIAS
);
356 if (kernfs_lockdep(kn
)) {
357 lock_acquired(&kn
->dep_map
, _RET_IP_
);
358 rwsem_release(&kn
->dep_map
, 1, _RET_IP_
);
361 kernfs_unmap_bin_file(kn
);
363 mutex_lock(&kernfs_mutex
);
367 * kernfs_get - get a reference count on a kernfs_node
368 * @kn: the target kernfs_node
370 void kernfs_get(struct kernfs_node
*kn
)
373 WARN_ON(!atomic_read(&kn
->count
));
374 atomic_inc(&kn
->count
);
377 EXPORT_SYMBOL_GPL(kernfs_get
);
380 * kernfs_put - put a reference count on a kernfs_node
381 * @kn: the target kernfs_node
383 * Put a reference count of @kn and destroy it if it reached zero.
385 void kernfs_put(struct kernfs_node
*kn
)
387 struct kernfs_node
*parent
;
388 struct kernfs_root
*root
;
390 if (!kn
|| !atomic_dec_and_test(&kn
->count
))
392 root
= kernfs_root(kn
);
395 * Moving/renaming is always done while holding reference.
396 * kn->parent won't change beneath us.
400 WARN_ONCE(atomic_read(&kn
->active
) != KN_DEACTIVATED_BIAS
,
401 "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
402 parent
? parent
->name
: "", kn
->name
, atomic_read(&kn
->active
));
404 if (kernfs_type(kn
) == KERNFS_LINK
)
405 kernfs_put(kn
->symlink
.target_kn
);
406 if (!(kn
->flags
& KERNFS_STATIC_NAME
))
409 if (kn
->iattr
->ia_secdata
)
410 security_release_secctx(kn
->iattr
->ia_secdata
,
411 kn
->iattr
->ia_secdata_len
);
412 simple_xattrs_free(&kn
->iattr
->xattrs
);
415 ida_simple_remove(&root
->ino_ida
, kn
->ino
);
416 kmem_cache_free(kernfs_node_cache
, kn
);
420 if (atomic_dec_and_test(&kn
->count
))
423 /* just released the root kn, free @root too */
424 ida_destroy(&root
->ino_ida
);
428 EXPORT_SYMBOL_GPL(kernfs_put
);
430 static int kernfs_dop_revalidate(struct dentry
*dentry
, unsigned int flags
)
432 struct kernfs_node
*kn
;
434 if (flags
& LOOKUP_RCU
)
437 /* Always perform fresh lookup for negatives */
438 if (!dentry
->d_inode
)
439 goto out_bad_unlocked
;
441 kn
= dentry
->d_fsdata
;
442 mutex_lock(&kernfs_mutex
);
444 /* The kernfs node has been deactivated */
445 if (!kernfs_active(kn
))
448 /* The kernfs node has been moved? */
449 if (dentry
->d_parent
->d_fsdata
!= kn
->parent
)
452 /* The kernfs node has been renamed */
453 if (strcmp(dentry
->d_name
.name
, kn
->name
) != 0)
456 /* The kernfs node has been moved to a different namespace */
457 if (kn
->parent
&& kernfs_ns_enabled(kn
->parent
) &&
458 kernfs_info(dentry
->d_sb
)->ns
!= kn
->ns
)
461 mutex_unlock(&kernfs_mutex
);
465 mutex_unlock(&kernfs_mutex
);
468 * @dentry doesn't match the underlying kernfs node, drop the
469 * dentry and force lookup. If we have submounts we must allow the
470 * vfs caches to lie about the state of the filesystem to prevent
471 * leaks and other nasty things, so use check_submounts_and_drop()
472 * instead of d_drop().
474 if (check_submounts_and_drop(dentry
) != 0)
480 static void kernfs_dop_release(struct dentry
*dentry
)
482 kernfs_put(dentry
->d_fsdata
);
485 const struct dentry_operations kernfs_dops
= {
486 .d_revalidate
= kernfs_dop_revalidate
,
487 .d_release
= kernfs_dop_release
,
491 * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
492 * @dentry: the dentry in question
494 * Return the kernfs_node associated with @dentry. If @dentry is not a
495 * kernfs one, %NULL is returned.
497 * While the returned kernfs_node will stay accessible as long as @dentry
498 * is accessible, the returned node can be in any state and the caller is
499 * fully responsible for determining what's accessible.
501 struct kernfs_node
*kernfs_node_from_dentry(struct dentry
*dentry
)
503 if (dentry
->d_sb
->s_op
== &kernfs_sops
)
504 return dentry
->d_fsdata
;
508 static struct kernfs_node
*__kernfs_new_node(struct kernfs_root
*root
,
509 const char *name
, umode_t mode
,
512 char *dup_name
= NULL
;
513 struct kernfs_node
*kn
;
516 if (!(flags
& KERNFS_STATIC_NAME
)) {
517 name
= dup_name
= kstrdup(name
, GFP_KERNEL
);
522 kn
= kmem_cache_zalloc(kernfs_node_cache
, GFP_KERNEL
);
526 ret
= ida_simple_get(&root
->ino_ida
, 1, 0, GFP_KERNEL
);
531 atomic_set(&kn
->count
, 1);
532 atomic_set(&kn
->active
, KN_DEACTIVATED_BIAS
);
533 RB_CLEAR_NODE(&kn
->rb
);
542 kmem_cache_free(kernfs_node_cache
, kn
);
548 struct kernfs_node
*kernfs_new_node(struct kernfs_node
*parent
,
549 const char *name
, umode_t mode
,
552 struct kernfs_node
*kn
;
554 kn
= __kernfs_new_node(kernfs_root(parent
), name
, mode
, flags
);
563 * kernfs_add_one - add kernfs_node to parent without warning
564 * @kn: kernfs_node to be added
566 * The caller must already have initialized @kn->parent. This
567 * function increments nlink of the parent's inode if @kn is a
568 * directory and link into the children list of the parent.
571 * 0 on success, -EEXIST if entry with the given name already
574 int kernfs_add_one(struct kernfs_node
*kn
)
576 struct kernfs_node
*parent
= kn
->parent
;
577 struct kernfs_iattrs
*ps_iattr
;
581 mutex_lock(&kernfs_mutex
);
584 has_ns
= kernfs_ns_enabled(parent
);
585 if (WARN(has_ns
!= (bool)kn
->ns
, KERN_WARNING
"kernfs: ns %s in '%s' for '%s'\n",
586 has_ns
? "required" : "invalid", parent
->name
, kn
->name
))
589 if (kernfs_type(parent
) != KERNFS_DIR
)
593 if ((parent
->flags
& KERNFS_ACTIVATED
) && !kernfs_active(parent
))
596 kn
->hash
= kernfs_name_hash(kn
->name
, kn
->ns
);
598 ret
= kernfs_link_sibling(kn
);
602 /* Update timestamps on the parent */
603 ps_iattr
= parent
->iattr
;
605 struct iattr
*ps_iattrs
= &ps_iattr
->ia_iattr
;
606 ps_iattrs
->ia_ctime
= ps_iattrs
->ia_mtime
= CURRENT_TIME
;
609 mutex_unlock(&kernfs_mutex
);
612 * Activate the new node unless CREATE_DEACTIVATED is requested.
613 * If not activated here, the kernfs user is responsible for
614 * activating the node with kernfs_activate(). A node which hasn't
615 * been activated is not visible to userland and its removal won't
616 * trigger deactivation.
618 if (!(kernfs_root(kn
)->flags
& KERNFS_ROOT_CREATE_DEACTIVATED
))
623 mutex_unlock(&kernfs_mutex
);
628 * kernfs_find_ns - find kernfs_node with the given name
629 * @parent: kernfs_node to search under
630 * @name: name to look for
631 * @ns: the namespace tag to use
633 * Look for kernfs_node with name @name under @parent. Returns pointer to
634 * the found kernfs_node on success, %NULL on failure.
636 static struct kernfs_node
*kernfs_find_ns(struct kernfs_node
*parent
,
637 const unsigned char *name
,
640 struct rb_node
*node
= parent
->dir
.children
.rb_node
;
641 bool has_ns
= kernfs_ns_enabled(parent
);
644 lockdep_assert_held(&kernfs_mutex
);
646 if (has_ns
!= (bool)ns
) {
647 WARN(1, KERN_WARNING
"kernfs: ns %s in '%s' for '%s'\n",
648 has_ns
? "required" : "invalid", parent
->name
, name
);
652 hash
= kernfs_name_hash(name
, ns
);
654 struct kernfs_node
*kn
;
658 result
= kernfs_name_compare(hash
, name
, ns
, kn
);
660 node
= node
->rb_left
;
662 node
= node
->rb_right
;
670 * kernfs_find_and_get_ns - find and get kernfs_node with the given name
671 * @parent: kernfs_node to search under
672 * @name: name to look for
673 * @ns: the namespace tag to use
675 * Look for kernfs_node with name @name under @parent and get a reference
676 * if found. This function may sleep and returns pointer to the found
677 * kernfs_node on success, %NULL on failure.
679 struct kernfs_node
*kernfs_find_and_get_ns(struct kernfs_node
*parent
,
680 const char *name
, const void *ns
)
682 struct kernfs_node
*kn
;
684 mutex_lock(&kernfs_mutex
);
685 kn
= kernfs_find_ns(parent
, name
, ns
);
687 mutex_unlock(&kernfs_mutex
);
691 EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns
);
694 * kernfs_create_root - create a new kernfs hierarchy
695 * @scops: optional syscall operations for the hierarchy
696 * @flags: KERNFS_ROOT_* flags
697 * @priv: opaque data associated with the new directory
699 * Returns the root of the new hierarchy on success, ERR_PTR() value on
702 struct kernfs_root
*kernfs_create_root(struct kernfs_syscall_ops
*scops
,
703 unsigned int flags
, void *priv
)
705 struct kernfs_root
*root
;
706 struct kernfs_node
*kn
;
708 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
710 return ERR_PTR(-ENOMEM
);
712 ida_init(&root
->ino_ida
);
714 kn
= __kernfs_new_node(root
, "", S_IFDIR
| S_IRUGO
| S_IXUGO
,
717 ida_destroy(&root
->ino_ida
);
719 return ERR_PTR(-ENOMEM
);
725 root
->syscall_ops
= scops
;
728 init_waitqueue_head(&root
->deactivate_waitq
);
730 if (!(root
->flags
& KERNFS_ROOT_CREATE_DEACTIVATED
))
737 * kernfs_destroy_root - destroy a kernfs hierarchy
738 * @root: root of the hierarchy to destroy
740 * Destroy the hierarchy anchored at @root by removing all existing
741 * directories and destroying @root.
743 void kernfs_destroy_root(struct kernfs_root
*root
)
745 kernfs_remove(root
->kn
); /* will also free @root */
749 * kernfs_create_dir_ns - create a directory
750 * @parent: parent in which to create a new directory
751 * @name: name of the new directory
752 * @mode: mode of the new directory
753 * @priv: opaque data associated with the new directory
754 * @ns: optional namespace tag of the directory
756 * Returns the created node on success, ERR_PTR() value on failure.
758 struct kernfs_node
*kernfs_create_dir_ns(struct kernfs_node
*parent
,
759 const char *name
, umode_t mode
,
760 void *priv
, const void *ns
)
762 struct kernfs_node
*kn
;
766 kn
= kernfs_new_node(parent
, name
, mode
| S_IFDIR
, KERNFS_DIR
);
768 return ERR_PTR(-ENOMEM
);
770 kn
->dir
.root
= parent
->dir
.root
;
775 rc
= kernfs_add_one(kn
);
783 static struct dentry
*kernfs_iop_lookup(struct inode
*dir
,
784 struct dentry
*dentry
,
788 struct kernfs_node
*parent
= dentry
->d_parent
->d_fsdata
;
789 struct kernfs_node
*kn
;
791 const void *ns
= NULL
;
793 mutex_lock(&kernfs_mutex
);
795 if (kernfs_ns_enabled(parent
))
796 ns
= kernfs_info(dir
->i_sb
)->ns
;
798 kn
= kernfs_find_ns(parent
, dentry
->d_name
.name
, ns
);
801 if (!kn
|| !kernfs_active(kn
)) {
806 dentry
->d_fsdata
= kn
;
808 /* attach dentry and inode */
809 inode
= kernfs_get_inode(dir
->i_sb
, kn
);
811 ret
= ERR_PTR(-ENOMEM
);
815 /* instantiate and hash dentry */
816 ret
= d_materialise_unique(dentry
, inode
);
818 mutex_unlock(&kernfs_mutex
);
822 static int kernfs_iop_mkdir(struct inode
*dir
, struct dentry
*dentry
,
825 struct kernfs_node
*parent
= dir
->i_private
;
826 struct kernfs_syscall_ops
*scops
= kernfs_root(parent
)->syscall_ops
;
829 if (!scops
|| !scops
->mkdir
)
832 if (!kernfs_get_active(parent
))
835 ret
= scops
->mkdir(parent
, dentry
->d_name
.name
, mode
);
837 kernfs_put_active(parent
);
841 static int kernfs_iop_rmdir(struct inode
*dir
, struct dentry
*dentry
)
843 struct kernfs_node
*kn
= dentry
->d_fsdata
;
844 struct kernfs_syscall_ops
*scops
= kernfs_root(kn
)->syscall_ops
;
847 if (!scops
|| !scops
->rmdir
)
850 if (!kernfs_get_active(kn
))
853 ret
= scops
->rmdir(kn
);
855 kernfs_put_active(kn
);
859 static int kernfs_iop_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
860 struct inode
*new_dir
, struct dentry
*new_dentry
)
862 struct kernfs_node
*kn
= old_dentry
->d_fsdata
;
863 struct kernfs_node
*new_parent
= new_dir
->i_private
;
864 struct kernfs_syscall_ops
*scops
= kernfs_root(kn
)->syscall_ops
;
867 if (!scops
|| !scops
->rename
)
870 if (!kernfs_get_active(kn
))
873 if (!kernfs_get_active(new_parent
)) {
874 kernfs_put_active(kn
);
878 ret
= scops
->rename(kn
, new_parent
, new_dentry
->d_name
.name
);
880 kernfs_put_active(new_parent
);
881 kernfs_put_active(kn
);
885 const struct inode_operations kernfs_dir_iops
= {
886 .lookup
= kernfs_iop_lookup
,
887 .permission
= kernfs_iop_permission
,
888 .setattr
= kernfs_iop_setattr
,
889 .getattr
= kernfs_iop_getattr
,
890 .setxattr
= kernfs_iop_setxattr
,
891 .removexattr
= kernfs_iop_removexattr
,
892 .getxattr
= kernfs_iop_getxattr
,
893 .listxattr
= kernfs_iop_listxattr
,
895 .mkdir
= kernfs_iop_mkdir
,
896 .rmdir
= kernfs_iop_rmdir
,
897 .rename
= kernfs_iop_rename
,
900 static struct kernfs_node
*kernfs_leftmost_descendant(struct kernfs_node
*pos
)
902 struct kernfs_node
*last
;
909 if (kernfs_type(pos
) != KERNFS_DIR
)
912 rbn
= rb_first(&pos
->dir
.children
);
923 * kernfs_next_descendant_post - find the next descendant for post-order walk
924 * @pos: the current position (%NULL to initiate traversal)
925 * @root: kernfs_node whose descendants to walk
927 * Find the next descendant to visit for post-order traversal of @root's
928 * descendants. @root is included in the iteration and the last node to be
931 static struct kernfs_node
*kernfs_next_descendant_post(struct kernfs_node
*pos
,
932 struct kernfs_node
*root
)
936 lockdep_assert_held(&kernfs_mutex
);
938 /* if first iteration, visit leftmost descendant which may be root */
940 return kernfs_leftmost_descendant(root
);
942 /* if we visited @root, we're done */
946 /* if there's an unvisited sibling, visit its leftmost descendant */
947 rbn
= rb_next(&pos
->rb
);
949 return kernfs_leftmost_descendant(rb_to_kn(rbn
));
951 /* no sibling left, visit parent */
956 * kernfs_activate - activate a node which started deactivated
957 * @kn: kernfs_node whose subtree is to be activated
959 * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node
960 * needs to be explicitly activated. A node which hasn't been activated
961 * isn't visible to userland and deactivation is skipped during its
962 * removal. This is useful to construct atomic init sequences where
963 * creation of multiple nodes should either succeed or fail atomically.
965 * The caller is responsible for ensuring that this function is not called
966 * after kernfs_remove*() is invoked on @kn.
968 void kernfs_activate(struct kernfs_node
*kn
)
970 struct kernfs_node
*pos
;
972 mutex_lock(&kernfs_mutex
);
975 while ((pos
= kernfs_next_descendant_post(pos
, kn
))) {
976 if (!pos
|| (pos
->flags
& KERNFS_ACTIVATED
))
979 WARN_ON_ONCE(pos
->parent
&& RB_EMPTY_NODE(&pos
->rb
));
980 WARN_ON_ONCE(atomic_read(&pos
->active
) != KN_DEACTIVATED_BIAS
);
982 atomic_sub(KN_DEACTIVATED_BIAS
, &pos
->active
);
983 pos
->flags
|= KERNFS_ACTIVATED
;
986 mutex_unlock(&kernfs_mutex
);
989 static void __kernfs_remove(struct kernfs_node
*kn
)
991 struct kernfs_node
*pos
;
993 lockdep_assert_held(&kernfs_mutex
);
996 * Short-circuit if non-root @kn has already finished removal.
997 * This is for kernfs_remove_self() which plays with active ref
1000 if (!kn
|| (kn
->parent
&& RB_EMPTY_NODE(&kn
->rb
)))
1003 pr_debug("kernfs %s: removing\n", kn
->name
);
1005 /* prevent any new usage under @kn by deactivating all nodes */
1007 while ((pos
= kernfs_next_descendant_post(pos
, kn
)))
1008 if (kernfs_active(pos
))
1009 atomic_add(KN_DEACTIVATED_BIAS
, &pos
->active
);
1011 /* deactivate and unlink the subtree node-by-node */
1013 pos
= kernfs_leftmost_descendant(kn
);
1016 * kernfs_drain() drops kernfs_mutex temporarily and @pos's
1017 * base ref could have been put by someone else by the time
1018 * the function returns. Make sure it doesn't go away
1024 * Drain iff @kn was activated. This avoids draining and
1025 * its lockdep annotations for nodes which have never been
1026 * activated and allows embedding kernfs_remove() in create
1027 * error paths without worrying about draining.
1029 if (kn
->flags
& KERNFS_ACTIVATED
)
1032 WARN_ON_ONCE(atomic_read(&kn
->active
) != KN_DEACTIVATED_BIAS
);
1035 * kernfs_unlink_sibling() succeeds once per node. Use it
1036 * to decide who's responsible for cleanups.
1038 if (!pos
->parent
|| kernfs_unlink_sibling(pos
)) {
1039 struct kernfs_iattrs
*ps_iattr
=
1040 pos
->parent
? pos
->parent
->iattr
: NULL
;
1042 /* update timestamps on the parent */
1044 ps_iattr
->ia_iattr
.ia_ctime
= CURRENT_TIME
;
1045 ps_iattr
->ia_iattr
.ia_mtime
= CURRENT_TIME
;
1052 } while (pos
!= kn
);
1056 * kernfs_remove - remove a kernfs_node recursively
1057 * @kn: the kernfs_node to remove
1059 * Remove @kn along with all its subdirectories and files.
1061 void kernfs_remove(struct kernfs_node
*kn
)
1063 mutex_lock(&kernfs_mutex
);
1064 __kernfs_remove(kn
);
1065 mutex_unlock(&kernfs_mutex
);
1069 * kernfs_break_active_protection - break out of active protection
1070 * @kn: the self kernfs_node
1072 * The caller must be running off of a kernfs operation which is invoked
1073 * with an active reference - e.g. one of kernfs_ops. Each invocation of
1074 * this function must also be matched with an invocation of
1075 * kernfs_unbreak_active_protection().
1077 * This function releases the active reference of @kn the caller is
1078 * holding. Once this function is called, @kn may be removed at any point
1079 * and the caller is solely responsible for ensuring that the objects it
1080 * dereferences are accessible.
1082 void kernfs_break_active_protection(struct kernfs_node
*kn
)
1085 * Take out ourself out of the active ref dependency chain. If
1086 * we're called without an active ref, lockdep will complain.
1088 kernfs_put_active(kn
);
1092 * kernfs_unbreak_active_protection - undo kernfs_break_active_protection()
1093 * @kn: the self kernfs_node
1095 * If kernfs_break_active_protection() was called, this function must be
1096 * invoked before finishing the kernfs operation. Note that while this
1097 * function restores the active reference, it doesn't and can't actually
1098 * restore the active protection - @kn may already or be in the process of
1099 * being removed. Once kernfs_break_active_protection() is invoked, that
1100 * protection is irreversibly gone for the kernfs operation instance.
1102 * While this function may be called at any point after
1103 * kernfs_break_active_protection() is invoked, its most useful location
1104 * would be right before the enclosing kernfs operation returns.
1106 void kernfs_unbreak_active_protection(struct kernfs_node
*kn
)
1109 * @kn->active could be in any state; however, the increment we do
1110 * here will be undone as soon as the enclosing kernfs operation
1111 * finishes and this temporary bump can't break anything. If @kn
1112 * is alive, nothing changes. If @kn is being deactivated, the
1113 * soon-to-follow put will either finish deactivation or restore
1114 * deactivated state. If @kn is already removed, the temporary
1115 * bump is guaranteed to be gone before @kn is released.
1117 atomic_inc(&kn
->active
);
1118 if (kernfs_lockdep(kn
))
1119 rwsem_acquire(&kn
->dep_map
, 0, 1, _RET_IP_
);
1123 * kernfs_remove_self - remove a kernfs_node from its own method
1124 * @kn: the self kernfs_node to remove
1126 * The caller must be running off of a kernfs operation which is invoked
1127 * with an active reference - e.g. one of kernfs_ops. This can be used to
1128 * implement a file operation which deletes itself.
1130 * For example, the "delete" file for a sysfs device directory can be
1131 * implemented by invoking kernfs_remove_self() on the "delete" file
1132 * itself. This function breaks the circular dependency of trying to
1133 * deactivate self while holding an active ref itself. It isn't necessary
1134 * to modify the usual removal path to use kernfs_remove_self(). The
1135 * "delete" implementation can simply invoke kernfs_remove_self() on self
1136 * before proceeding with the usual removal path. kernfs will ignore later
1137 * kernfs_remove() on self.
1139 * kernfs_remove_self() can be called multiple times concurrently on the
1140 * same kernfs_node. Only the first one actually performs removal and
1141 * returns %true. All others will wait until the kernfs operation which
1142 * won self-removal finishes and return %false. Note that the losers wait
1143 * for the completion of not only the winning kernfs_remove_self() but also
1144 * the whole kernfs_ops which won the arbitration. This can be used to
1145 * guarantee, for example, all concurrent writes to a "delete" file to
1146 * finish only after the whole operation is complete.
1148 bool kernfs_remove_self(struct kernfs_node
*kn
)
1152 mutex_lock(&kernfs_mutex
);
1153 kernfs_break_active_protection(kn
);
1156 * SUICIDAL is used to arbitrate among competing invocations. Only
1157 * the first one will actually perform removal. When the removal
1158 * is complete, SUICIDED is set and the active ref is restored
1159 * while holding kernfs_mutex. The ones which lost arbitration
1160 * waits for SUICDED && drained which can happen only after the
1161 * enclosing kernfs operation which executed the winning instance
1162 * of kernfs_remove_self() finished.
1164 if (!(kn
->flags
& KERNFS_SUICIDAL
)) {
1165 kn
->flags
|= KERNFS_SUICIDAL
;
1166 __kernfs_remove(kn
);
1167 kn
->flags
|= KERNFS_SUICIDED
;
1170 wait_queue_head_t
*waitq
= &kernfs_root(kn
)->deactivate_waitq
;
1174 prepare_to_wait(waitq
, &wait
, TASK_UNINTERRUPTIBLE
);
1176 if ((kn
->flags
& KERNFS_SUICIDED
) &&
1177 atomic_read(&kn
->active
) == KN_DEACTIVATED_BIAS
)
1180 mutex_unlock(&kernfs_mutex
);
1182 mutex_lock(&kernfs_mutex
);
1184 finish_wait(waitq
, &wait
);
1185 WARN_ON_ONCE(!RB_EMPTY_NODE(&kn
->rb
));
1190 * This must be done while holding kernfs_mutex; otherwise, waiting
1191 * for SUICIDED && deactivated could finish prematurely.
1193 kernfs_unbreak_active_protection(kn
);
1195 mutex_unlock(&kernfs_mutex
);
1200 * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
1201 * @parent: parent of the target
1202 * @name: name of the kernfs_node to remove
1203 * @ns: namespace tag of the kernfs_node to remove
1205 * Look for the kernfs_node with @name and @ns under @parent and remove it.
1206 * Returns 0 on success, -ENOENT if such entry doesn't exist.
1208 int kernfs_remove_by_name_ns(struct kernfs_node
*parent
, const char *name
,
1211 struct kernfs_node
*kn
;
1214 WARN(1, KERN_WARNING
"kernfs: can not remove '%s', no directory\n",
1219 mutex_lock(&kernfs_mutex
);
1221 kn
= kernfs_find_ns(parent
, name
, ns
);
1223 __kernfs_remove(kn
);
1225 mutex_unlock(&kernfs_mutex
);
1234 * kernfs_rename_ns - move and rename a kernfs_node
1236 * @new_parent: new parent to put @sd under
1237 * @new_name: new name
1238 * @new_ns: new namespace tag
1240 int kernfs_rename_ns(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
1241 const char *new_name
, const void *new_ns
)
1243 struct kernfs_node
*old_parent
;
1244 const char *old_name
= NULL
;
1247 /* can't move or rename root */
1251 mutex_lock(&kernfs_mutex
);
1254 if (!kernfs_active(kn
) || !kernfs_active(new_parent
))
1258 if ((kn
->parent
== new_parent
) && (kn
->ns
== new_ns
) &&
1259 (strcmp(kn
->name
, new_name
) == 0))
1260 goto out
; /* nothing to rename */
1263 if (kernfs_find_ns(new_parent
, new_name
, new_ns
))
1266 /* rename kernfs_node */
1267 if (strcmp(kn
->name
, new_name
) != 0) {
1269 new_name
= kstrdup(new_name
, GFP_KERNEL
);
1277 * Move to the appropriate place in the appropriate directories rbtree.
1279 kernfs_unlink_sibling(kn
);
1280 kernfs_get(new_parent
);
1282 /* rename_lock protects ->parent and ->name accessors */
1283 spin_lock_irq(&kernfs_rename_lock
);
1285 old_parent
= kn
->parent
;
1286 kn
->parent
= new_parent
;
1290 if (!(kn
->flags
& KERNFS_STATIC_NAME
))
1291 old_name
= kn
->name
;
1292 kn
->flags
&= ~KERNFS_STATIC_NAME
;
1293 kn
->name
= new_name
;
1296 spin_unlock_irq(&kernfs_rename_lock
);
1298 kn
->hash
= kernfs_name_hash(kn
->name
, kn
->ns
);
1299 kernfs_link_sibling(kn
);
1301 kernfs_put(old_parent
);
1306 mutex_unlock(&kernfs_mutex
);
1310 /* Relationship between s_mode and the DT_xxx types */
1311 static inline unsigned char dt_type(struct kernfs_node
*kn
)
1313 return (kn
->mode
>> 12) & 15;
1316 static int kernfs_dir_fop_release(struct inode
*inode
, struct file
*filp
)
1318 kernfs_put(filp
->private_data
);
1322 static struct kernfs_node
*kernfs_dir_pos(const void *ns
,
1323 struct kernfs_node
*parent
, loff_t hash
, struct kernfs_node
*pos
)
1326 int valid
= kernfs_active(pos
) &&
1327 pos
->parent
== parent
&& hash
== pos
->hash
;
1332 if (!pos
&& (hash
> 1) && (hash
< INT_MAX
)) {
1333 struct rb_node
*node
= parent
->dir
.children
.rb_node
;
1335 pos
= rb_to_kn(node
);
1337 if (hash
< pos
->hash
)
1338 node
= node
->rb_left
;
1339 else if (hash
> pos
->hash
)
1340 node
= node
->rb_right
;
1345 /* Skip over entries which are dying/dead or in the wrong namespace */
1346 while (pos
&& (!kernfs_active(pos
) || pos
->ns
!= ns
)) {
1347 struct rb_node
*node
= rb_next(&pos
->rb
);
1351 pos
= rb_to_kn(node
);
1356 static struct kernfs_node
*kernfs_dir_next_pos(const void *ns
,
1357 struct kernfs_node
*parent
, ino_t ino
, struct kernfs_node
*pos
)
1359 pos
= kernfs_dir_pos(ns
, parent
, ino
, pos
);
1362 struct rb_node
*node
= rb_next(&pos
->rb
);
1366 pos
= rb_to_kn(node
);
1367 } while (pos
&& (!kernfs_active(pos
) || pos
->ns
!= ns
));
1372 static int kernfs_fop_readdir(struct file
*file
, struct dir_context
*ctx
)
1374 struct dentry
*dentry
= file
->f_path
.dentry
;
1375 struct kernfs_node
*parent
= dentry
->d_fsdata
;
1376 struct kernfs_node
*pos
= file
->private_data
;
1377 const void *ns
= NULL
;
1379 if (!dir_emit_dots(file
, ctx
))
1381 mutex_lock(&kernfs_mutex
);
1383 if (kernfs_ns_enabled(parent
))
1384 ns
= kernfs_info(dentry
->d_sb
)->ns
;
1386 for (pos
= kernfs_dir_pos(ns
, parent
, ctx
->pos
, pos
);
1388 pos
= kernfs_dir_next_pos(ns
, parent
, ctx
->pos
, pos
)) {
1389 const char *name
= pos
->name
;
1390 unsigned int type
= dt_type(pos
);
1391 int len
= strlen(name
);
1392 ino_t ino
= pos
->ino
;
1394 ctx
->pos
= pos
->hash
;
1395 file
->private_data
= pos
;
1398 mutex_unlock(&kernfs_mutex
);
1399 if (!dir_emit(ctx
, name
, len
, ino
, type
))
1401 mutex_lock(&kernfs_mutex
);
1403 mutex_unlock(&kernfs_mutex
);
1404 file
->private_data
= NULL
;
1409 static loff_t
kernfs_dir_fop_llseek(struct file
*file
, loff_t offset
,
1412 struct inode
*inode
= file_inode(file
);
1415 mutex_lock(&inode
->i_mutex
);
1416 ret
= generic_file_llseek(file
, offset
, whence
);
1417 mutex_unlock(&inode
->i_mutex
);
1422 const struct file_operations kernfs_dir_fops
= {
1423 .read
= generic_read_dir
,
1424 .iterate
= kernfs_fop_readdir
,
1425 .release
= kernfs_dir_fop_release
,
1426 .llseek
= kernfs_dir_fop_llseek
,