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
);
115 EXPORT_SYMBOL_GPL(kernfs_path
);
118 * pr_cont_kernfs_name - pr_cont name of a kernfs_node
119 * @kn: kernfs_node of interest
121 * This function can be called from any context.
123 void pr_cont_kernfs_name(struct kernfs_node
*kn
)
127 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
129 kernfs_name_locked(kn
, kernfs_pr_cont_buf
, sizeof(kernfs_pr_cont_buf
));
130 pr_cont("%s", kernfs_pr_cont_buf
);
132 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
136 * pr_cont_kernfs_path - pr_cont path of a kernfs_node
137 * @kn: kernfs_node of interest
139 * This function can be called from any context.
141 void pr_cont_kernfs_path(struct kernfs_node
*kn
)
146 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
148 p
= kernfs_path_locked(kn
, kernfs_pr_cont_buf
,
149 sizeof(kernfs_pr_cont_buf
));
153 pr_cont("<name too long>");
155 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
159 * kernfs_get_parent - determine the parent node and pin it
160 * @kn: kernfs_node of interest
162 * Determines @kn's parent, pins and returns it. This function can be
163 * called from any context.
165 struct kernfs_node
*kernfs_get_parent(struct kernfs_node
*kn
)
167 struct kernfs_node
*parent
;
170 spin_lock_irqsave(&kernfs_rename_lock
, flags
);
173 spin_unlock_irqrestore(&kernfs_rename_lock
, flags
);
180 * @name: Null terminated string to hash
181 * @ns: Namespace tag to hash
183 * Returns 31 bit hash of ns + name (so it fits in an off_t )
185 static unsigned int kernfs_name_hash(const char *name
, const void *ns
)
187 unsigned long hash
= init_name_hash();
188 unsigned int len
= strlen(name
);
190 hash
= partial_name_hash(*name
++, hash
);
191 hash
= (end_name_hash(hash
) ^ hash_ptr((void *)ns
, 31));
193 /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
201 static int kernfs_name_compare(unsigned int hash
, const char *name
,
202 const void *ns
, const struct kernfs_node
*kn
)
212 return strcmp(name
, kn
->name
);
215 static int kernfs_sd_compare(const struct kernfs_node
*left
,
216 const struct kernfs_node
*right
)
218 return kernfs_name_compare(left
->hash
, left
->name
, left
->ns
, right
);
222 * kernfs_link_sibling - link kernfs_node into sibling rbtree
223 * @kn: kernfs_node of interest
225 * Link @kn into its sibling rbtree which starts from
226 * @kn->parent->dir.children.
229 * mutex_lock(kernfs_mutex)
232 * 0 on susccess -EEXIST on failure.
234 static int kernfs_link_sibling(struct kernfs_node
*kn
)
236 struct rb_node
**node
= &kn
->parent
->dir
.children
.rb_node
;
237 struct rb_node
*parent
= NULL
;
240 struct kernfs_node
*pos
;
243 pos
= rb_to_kn(*node
);
245 result
= kernfs_sd_compare(kn
, pos
);
247 node
= &pos
->rb
.rb_left
;
249 node
= &pos
->rb
.rb_right
;
254 /* add new node and rebalance the tree */
255 rb_link_node(&kn
->rb
, parent
, node
);
256 rb_insert_color(&kn
->rb
, &kn
->parent
->dir
.children
);
258 /* successfully added, account subdir number */
259 if (kernfs_type(kn
) == KERNFS_DIR
)
260 kn
->parent
->dir
.subdirs
++;
266 * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
267 * @kn: kernfs_node of interest
269 * Try to unlink @kn from its sibling rbtree which starts from
270 * kn->parent->dir.children. Returns %true if @kn was actually
271 * removed, %false if @kn wasn't on the rbtree.
274 * mutex_lock(kernfs_mutex)
276 static bool kernfs_unlink_sibling(struct kernfs_node
*kn
)
278 if (RB_EMPTY_NODE(&kn
->rb
))
281 if (kernfs_type(kn
) == KERNFS_DIR
)
282 kn
->parent
->dir
.subdirs
--;
284 rb_erase(&kn
->rb
, &kn
->parent
->dir
.children
);
285 RB_CLEAR_NODE(&kn
->rb
);
290 * kernfs_get_active - get an active reference to kernfs_node
291 * @kn: kernfs_node to get an active reference to
293 * Get an active reference of @kn. This function is noop if @kn
297 * Pointer to @kn on success, NULL on failure.
299 struct kernfs_node
*kernfs_get_active(struct kernfs_node
*kn
)
304 if (!atomic_inc_unless_negative(&kn
->active
))
307 if (kernfs_lockdep(kn
))
308 rwsem_acquire_read(&kn
->dep_map
, 0, 1, _RET_IP_
);
313 * kernfs_put_active - put an active reference to kernfs_node
314 * @kn: kernfs_node to put an active reference to
316 * Put an active reference to @kn. This function is noop if @kn
319 void kernfs_put_active(struct kernfs_node
*kn
)
321 struct kernfs_root
*root
= kernfs_root(kn
);
327 if (kernfs_lockdep(kn
))
328 rwsem_release(&kn
->dep_map
, 1, _RET_IP_
);
329 v
= atomic_dec_return(&kn
->active
);
330 if (likely(v
!= KN_DEACTIVATED_BIAS
))
333 wake_up_all(&root
->deactivate_waitq
);
337 * kernfs_drain - drain kernfs_node
338 * @kn: kernfs_node to drain
340 * Drain existing usages and nuke all existing mmaps of @kn. Mutiple
341 * removers may invoke this function concurrently on @kn and all will
342 * return after draining is complete.
344 static void kernfs_drain(struct kernfs_node
*kn
)
345 __releases(&kernfs_mutex
) __acquires(&kernfs_mutex
)
347 struct kernfs_root
*root
= kernfs_root(kn
);
349 lockdep_assert_held(&kernfs_mutex
);
350 WARN_ON_ONCE(kernfs_active(kn
));
352 mutex_unlock(&kernfs_mutex
);
354 if (kernfs_lockdep(kn
)) {
355 rwsem_acquire(&kn
->dep_map
, 0, 0, _RET_IP_
);
356 if (atomic_read(&kn
->active
) != KN_DEACTIVATED_BIAS
)
357 lock_contended(&kn
->dep_map
, _RET_IP_
);
360 /* but everyone should wait for draining */
361 wait_event(root
->deactivate_waitq
,
362 atomic_read(&kn
->active
) == KN_DEACTIVATED_BIAS
);
364 if (kernfs_lockdep(kn
)) {
365 lock_acquired(&kn
->dep_map
, _RET_IP_
);
366 rwsem_release(&kn
->dep_map
, 1, _RET_IP_
);
369 kernfs_unmap_bin_file(kn
);
371 mutex_lock(&kernfs_mutex
);
375 * kernfs_get - get a reference count on a kernfs_node
376 * @kn: the target kernfs_node
378 void kernfs_get(struct kernfs_node
*kn
)
381 WARN_ON(!atomic_read(&kn
->count
));
382 atomic_inc(&kn
->count
);
385 EXPORT_SYMBOL_GPL(kernfs_get
);
388 * kernfs_put - put a reference count on a kernfs_node
389 * @kn: the target kernfs_node
391 * Put a reference count of @kn and destroy it if it reached zero.
393 void kernfs_put(struct kernfs_node
*kn
)
395 struct kernfs_node
*parent
;
396 struct kernfs_root
*root
;
398 if (!kn
|| !atomic_dec_and_test(&kn
->count
))
400 root
= kernfs_root(kn
);
403 * Moving/renaming is always done while holding reference.
404 * kn->parent won't change beneath us.
408 WARN_ONCE(atomic_read(&kn
->active
) != KN_DEACTIVATED_BIAS
,
409 "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
410 parent
? parent
->name
: "", kn
->name
, atomic_read(&kn
->active
));
412 if (kernfs_type(kn
) == KERNFS_LINK
)
413 kernfs_put(kn
->symlink
.target_kn
);
415 kfree_const(kn
->name
);
418 if (kn
->iattr
->ia_secdata
)
419 security_release_secctx(kn
->iattr
->ia_secdata
,
420 kn
->iattr
->ia_secdata_len
);
421 simple_xattrs_free(&kn
->iattr
->xattrs
);
424 ida_simple_remove(&root
->ino_ida
, kn
->ino
);
425 kmem_cache_free(kernfs_node_cache
, kn
);
429 if (atomic_dec_and_test(&kn
->count
))
432 /* just released the root kn, free @root too */
433 ida_destroy(&root
->ino_ida
);
437 EXPORT_SYMBOL_GPL(kernfs_put
);
439 static int kernfs_dop_revalidate(struct dentry
*dentry
, unsigned int flags
)
441 struct kernfs_node
*kn
;
443 if (flags
& LOOKUP_RCU
)
446 /* Always perform fresh lookup for negatives */
447 if (d_really_is_negative(dentry
))
448 goto out_bad_unlocked
;
450 kn
= dentry
->d_fsdata
;
451 mutex_lock(&kernfs_mutex
);
453 /* The kernfs node has been deactivated */
454 if (!kernfs_active(kn
))
457 /* The kernfs node has been moved? */
458 if (dentry
->d_parent
->d_fsdata
!= kn
->parent
)
461 /* The kernfs node has been renamed */
462 if (strcmp(dentry
->d_name
.name
, kn
->name
) != 0)
465 /* The kernfs node has been moved to a different namespace */
466 if (kn
->parent
&& kernfs_ns_enabled(kn
->parent
) &&
467 kernfs_info(dentry
->d_sb
)->ns
!= kn
->ns
)
470 mutex_unlock(&kernfs_mutex
);
473 mutex_unlock(&kernfs_mutex
);
478 static void kernfs_dop_release(struct dentry
*dentry
)
480 kernfs_put(dentry
->d_fsdata
);
483 const struct dentry_operations kernfs_dops
= {
484 .d_revalidate
= kernfs_dop_revalidate
,
485 .d_release
= kernfs_dop_release
,
489 * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
490 * @dentry: the dentry in question
492 * Return the kernfs_node associated with @dentry. If @dentry is not a
493 * kernfs one, %NULL is returned.
495 * While the returned kernfs_node will stay accessible as long as @dentry
496 * is accessible, the returned node can be in any state and the caller is
497 * fully responsible for determining what's accessible.
499 struct kernfs_node
*kernfs_node_from_dentry(struct dentry
*dentry
)
501 if (dentry
->d_sb
->s_op
== &kernfs_sops
)
502 return dentry
->d_fsdata
;
506 static struct kernfs_node
*__kernfs_new_node(struct kernfs_root
*root
,
507 const char *name
, umode_t mode
,
510 struct kernfs_node
*kn
;
513 name
= kstrdup_const(name
, GFP_KERNEL
);
517 kn
= kmem_cache_zalloc(kernfs_node_cache
, GFP_KERNEL
);
521 ret
= ida_simple_get(&root
->ino_ida
, 1, 0, GFP_KERNEL
);
526 atomic_set(&kn
->count
, 1);
527 atomic_set(&kn
->active
, KN_DEACTIVATED_BIAS
);
528 RB_CLEAR_NODE(&kn
->rb
);
537 kmem_cache_free(kernfs_node_cache
, kn
);
543 struct kernfs_node
*kernfs_new_node(struct kernfs_node
*parent
,
544 const char *name
, umode_t mode
,
547 struct kernfs_node
*kn
;
549 kn
= __kernfs_new_node(kernfs_root(parent
), name
, mode
, flags
);
558 * kernfs_add_one - add kernfs_node to parent without warning
559 * @kn: kernfs_node to be added
561 * The caller must already have initialized @kn->parent. This
562 * function increments nlink of the parent's inode if @kn is a
563 * directory and link into the children list of the parent.
566 * 0 on success, -EEXIST if entry with the given name already
569 int kernfs_add_one(struct kernfs_node
*kn
)
571 struct kernfs_node
*parent
= kn
->parent
;
572 struct kernfs_iattrs
*ps_iattr
;
576 mutex_lock(&kernfs_mutex
);
579 has_ns
= kernfs_ns_enabled(parent
);
580 if (WARN(has_ns
!= (bool)kn
->ns
, KERN_WARNING
"kernfs: ns %s in '%s' for '%s'\n",
581 has_ns
? "required" : "invalid", parent
->name
, kn
->name
))
584 if (kernfs_type(parent
) != KERNFS_DIR
)
588 if ((parent
->flags
& KERNFS_ACTIVATED
) && !kernfs_active(parent
))
591 kn
->hash
= kernfs_name_hash(kn
->name
, kn
->ns
);
593 ret
= kernfs_link_sibling(kn
);
597 /* Update timestamps on the parent */
598 ps_iattr
= parent
->iattr
;
600 struct iattr
*ps_iattrs
= &ps_iattr
->ia_iattr
;
601 ps_iattrs
->ia_ctime
= ps_iattrs
->ia_mtime
= CURRENT_TIME
;
604 mutex_unlock(&kernfs_mutex
);
607 * Activate the new node unless CREATE_DEACTIVATED is requested.
608 * If not activated here, the kernfs user is responsible for
609 * activating the node with kernfs_activate(). A node which hasn't
610 * been activated is not visible to userland and its removal won't
611 * trigger deactivation.
613 if (!(kernfs_root(kn
)->flags
& KERNFS_ROOT_CREATE_DEACTIVATED
))
618 mutex_unlock(&kernfs_mutex
);
623 * kernfs_find_ns - find kernfs_node with the given name
624 * @parent: kernfs_node to search under
625 * @name: name to look for
626 * @ns: the namespace tag to use
628 * Look for kernfs_node with name @name under @parent. Returns pointer to
629 * the found kernfs_node on success, %NULL on failure.
631 static struct kernfs_node
*kernfs_find_ns(struct kernfs_node
*parent
,
632 const unsigned char *name
,
635 struct rb_node
*node
= parent
->dir
.children
.rb_node
;
636 bool has_ns
= kernfs_ns_enabled(parent
);
639 lockdep_assert_held(&kernfs_mutex
);
641 if (has_ns
!= (bool)ns
) {
642 WARN(1, KERN_WARNING
"kernfs: ns %s in '%s' for '%s'\n",
643 has_ns
? "required" : "invalid", parent
->name
, name
);
647 hash
= kernfs_name_hash(name
, ns
);
649 struct kernfs_node
*kn
;
653 result
= kernfs_name_compare(hash
, name
, ns
, kn
);
655 node
= node
->rb_left
;
657 node
= node
->rb_right
;
665 * kernfs_find_and_get_ns - find and get kernfs_node with the given name
666 * @parent: kernfs_node to search under
667 * @name: name to look for
668 * @ns: the namespace tag to use
670 * Look for kernfs_node with name @name under @parent and get a reference
671 * if found. This function may sleep and returns pointer to the found
672 * kernfs_node on success, %NULL on failure.
674 struct kernfs_node
*kernfs_find_and_get_ns(struct kernfs_node
*parent
,
675 const char *name
, const void *ns
)
677 struct kernfs_node
*kn
;
679 mutex_lock(&kernfs_mutex
);
680 kn
= kernfs_find_ns(parent
, name
, ns
);
682 mutex_unlock(&kernfs_mutex
);
686 EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns
);
689 * kernfs_create_root - create a new kernfs hierarchy
690 * @scops: optional syscall operations for the hierarchy
691 * @flags: KERNFS_ROOT_* flags
692 * @priv: opaque data associated with the new directory
694 * Returns the root of the new hierarchy on success, ERR_PTR() value on
697 struct kernfs_root
*kernfs_create_root(struct kernfs_syscall_ops
*scops
,
698 unsigned int flags
, void *priv
)
700 struct kernfs_root
*root
;
701 struct kernfs_node
*kn
;
703 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
705 return ERR_PTR(-ENOMEM
);
707 ida_init(&root
->ino_ida
);
708 INIT_LIST_HEAD(&root
->supers
);
710 kn
= __kernfs_new_node(root
, "", S_IFDIR
| S_IRUGO
| S_IXUGO
,
713 ida_destroy(&root
->ino_ida
);
715 return ERR_PTR(-ENOMEM
);
721 root
->syscall_ops
= scops
;
724 init_waitqueue_head(&root
->deactivate_waitq
);
726 if (!(root
->flags
& KERNFS_ROOT_CREATE_DEACTIVATED
))
733 * kernfs_destroy_root - destroy a kernfs hierarchy
734 * @root: root of the hierarchy to destroy
736 * Destroy the hierarchy anchored at @root by removing all existing
737 * directories and destroying @root.
739 void kernfs_destroy_root(struct kernfs_root
*root
)
741 kernfs_remove(root
->kn
); /* will also free @root */
745 * kernfs_create_dir_ns - create a directory
746 * @parent: parent in which to create a new directory
747 * @name: name of the new directory
748 * @mode: mode of the new directory
749 * @priv: opaque data associated with the new directory
750 * @ns: optional namespace tag of the directory
752 * Returns the created node on success, ERR_PTR() value on failure.
754 struct kernfs_node
*kernfs_create_dir_ns(struct kernfs_node
*parent
,
755 const char *name
, umode_t mode
,
756 void *priv
, const void *ns
)
758 struct kernfs_node
*kn
;
762 kn
= kernfs_new_node(parent
, name
, mode
| S_IFDIR
, KERNFS_DIR
);
764 return ERR_PTR(-ENOMEM
);
766 kn
->dir
.root
= parent
->dir
.root
;
771 rc
= kernfs_add_one(kn
);
779 static struct dentry
*kernfs_iop_lookup(struct inode
*dir
,
780 struct dentry
*dentry
,
784 struct kernfs_node
*parent
= dentry
->d_parent
->d_fsdata
;
785 struct kernfs_node
*kn
;
787 const void *ns
= NULL
;
789 mutex_lock(&kernfs_mutex
);
791 if (kernfs_ns_enabled(parent
))
792 ns
= kernfs_info(dir
->i_sb
)->ns
;
794 kn
= kernfs_find_ns(parent
, dentry
->d_name
.name
, ns
);
797 if (!kn
|| !kernfs_active(kn
)) {
802 dentry
->d_fsdata
= kn
;
804 /* attach dentry and inode */
805 inode
= kernfs_get_inode(dir
->i_sb
, kn
);
807 ret
= ERR_PTR(-ENOMEM
);
811 /* instantiate and hash dentry */
812 ret
= d_splice_alias(inode
, dentry
);
814 mutex_unlock(&kernfs_mutex
);
818 static int kernfs_iop_mkdir(struct inode
*dir
, struct dentry
*dentry
,
821 struct kernfs_node
*parent
= dir
->i_private
;
822 struct kernfs_syscall_ops
*scops
= kernfs_root(parent
)->syscall_ops
;
825 if (!scops
|| !scops
->mkdir
)
828 if (!kernfs_get_active(parent
))
831 ret
= scops
->mkdir(parent
, dentry
->d_name
.name
, mode
);
833 kernfs_put_active(parent
);
837 static int kernfs_iop_rmdir(struct inode
*dir
, struct dentry
*dentry
)
839 struct kernfs_node
*kn
= dentry
->d_fsdata
;
840 struct kernfs_syscall_ops
*scops
= kernfs_root(kn
)->syscall_ops
;
843 if (!scops
|| !scops
->rmdir
)
846 if (!kernfs_get_active(kn
))
849 ret
= scops
->rmdir(kn
);
851 kernfs_put_active(kn
);
855 static int kernfs_iop_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
856 struct inode
*new_dir
, struct dentry
*new_dentry
)
858 struct kernfs_node
*kn
= old_dentry
->d_fsdata
;
859 struct kernfs_node
*new_parent
= new_dir
->i_private
;
860 struct kernfs_syscall_ops
*scops
= kernfs_root(kn
)->syscall_ops
;
863 if (!scops
|| !scops
->rename
)
866 if (!kernfs_get_active(kn
))
869 if (!kernfs_get_active(new_parent
)) {
870 kernfs_put_active(kn
);
874 ret
= scops
->rename(kn
, new_parent
, new_dentry
->d_name
.name
);
876 kernfs_put_active(new_parent
);
877 kernfs_put_active(kn
);
881 const struct inode_operations kernfs_dir_iops
= {
882 .lookup
= kernfs_iop_lookup
,
883 .permission
= kernfs_iop_permission
,
884 .setattr
= kernfs_iop_setattr
,
885 .getattr
= kernfs_iop_getattr
,
886 .setxattr
= kernfs_iop_setxattr
,
887 .removexattr
= kernfs_iop_removexattr
,
888 .getxattr
= kernfs_iop_getxattr
,
889 .listxattr
= kernfs_iop_listxattr
,
891 .mkdir
= kernfs_iop_mkdir
,
892 .rmdir
= kernfs_iop_rmdir
,
893 .rename
= kernfs_iop_rename
,
896 static struct kernfs_node
*kernfs_leftmost_descendant(struct kernfs_node
*pos
)
898 struct kernfs_node
*last
;
905 if (kernfs_type(pos
) != KERNFS_DIR
)
908 rbn
= rb_first(&pos
->dir
.children
);
919 * kernfs_next_descendant_post - find the next descendant for post-order walk
920 * @pos: the current position (%NULL to initiate traversal)
921 * @root: kernfs_node whose descendants to walk
923 * Find the next descendant to visit for post-order traversal of @root's
924 * descendants. @root is included in the iteration and the last node to be
927 static struct kernfs_node
*kernfs_next_descendant_post(struct kernfs_node
*pos
,
928 struct kernfs_node
*root
)
932 lockdep_assert_held(&kernfs_mutex
);
934 /* if first iteration, visit leftmost descendant which may be root */
936 return kernfs_leftmost_descendant(root
);
938 /* if we visited @root, we're done */
942 /* if there's an unvisited sibling, visit its leftmost descendant */
943 rbn
= rb_next(&pos
->rb
);
945 return kernfs_leftmost_descendant(rb_to_kn(rbn
));
947 /* no sibling left, visit parent */
952 * kernfs_activate - activate a node which started deactivated
953 * @kn: kernfs_node whose subtree is to be activated
955 * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node
956 * needs to be explicitly activated. A node which hasn't been activated
957 * isn't visible to userland and deactivation is skipped during its
958 * removal. This is useful to construct atomic init sequences where
959 * creation of multiple nodes should either succeed or fail atomically.
961 * The caller is responsible for ensuring that this function is not called
962 * after kernfs_remove*() is invoked on @kn.
964 void kernfs_activate(struct kernfs_node
*kn
)
966 struct kernfs_node
*pos
;
968 mutex_lock(&kernfs_mutex
);
971 while ((pos
= kernfs_next_descendant_post(pos
, kn
))) {
972 if (!pos
|| (pos
->flags
& KERNFS_ACTIVATED
))
975 WARN_ON_ONCE(pos
->parent
&& RB_EMPTY_NODE(&pos
->rb
));
976 WARN_ON_ONCE(atomic_read(&pos
->active
) != KN_DEACTIVATED_BIAS
);
978 atomic_sub(KN_DEACTIVATED_BIAS
, &pos
->active
);
979 pos
->flags
|= KERNFS_ACTIVATED
;
982 mutex_unlock(&kernfs_mutex
);
985 static void __kernfs_remove(struct kernfs_node
*kn
)
987 struct kernfs_node
*pos
;
989 lockdep_assert_held(&kernfs_mutex
);
992 * Short-circuit if non-root @kn has already finished removal.
993 * This is for kernfs_remove_self() which plays with active ref
996 if (!kn
|| (kn
->parent
&& RB_EMPTY_NODE(&kn
->rb
)))
999 pr_debug("kernfs %s: removing\n", kn
->name
);
1001 /* prevent any new usage under @kn by deactivating all nodes */
1003 while ((pos
= kernfs_next_descendant_post(pos
, kn
)))
1004 if (kernfs_active(pos
))
1005 atomic_add(KN_DEACTIVATED_BIAS
, &pos
->active
);
1007 /* deactivate and unlink the subtree node-by-node */
1009 pos
= kernfs_leftmost_descendant(kn
);
1012 * kernfs_drain() drops kernfs_mutex temporarily and @pos's
1013 * base ref could have been put by someone else by the time
1014 * the function returns. Make sure it doesn't go away
1020 * Drain iff @kn was activated. This avoids draining and
1021 * its lockdep annotations for nodes which have never been
1022 * activated and allows embedding kernfs_remove() in create
1023 * error paths without worrying about draining.
1025 if (kn
->flags
& KERNFS_ACTIVATED
)
1028 WARN_ON_ONCE(atomic_read(&kn
->active
) != KN_DEACTIVATED_BIAS
);
1031 * kernfs_unlink_sibling() succeeds once per node. Use it
1032 * to decide who's responsible for cleanups.
1034 if (!pos
->parent
|| kernfs_unlink_sibling(pos
)) {
1035 struct kernfs_iattrs
*ps_iattr
=
1036 pos
->parent
? pos
->parent
->iattr
: NULL
;
1038 /* update timestamps on the parent */
1040 ps_iattr
->ia_iattr
.ia_ctime
= CURRENT_TIME
;
1041 ps_iattr
->ia_iattr
.ia_mtime
= CURRENT_TIME
;
1048 } while (pos
!= kn
);
1052 * kernfs_remove - remove a kernfs_node recursively
1053 * @kn: the kernfs_node to remove
1055 * Remove @kn along with all its subdirectories and files.
1057 void kernfs_remove(struct kernfs_node
*kn
)
1059 mutex_lock(&kernfs_mutex
);
1060 __kernfs_remove(kn
);
1061 mutex_unlock(&kernfs_mutex
);
1065 * kernfs_break_active_protection - break out of active protection
1066 * @kn: the self kernfs_node
1068 * The caller must be running off of a kernfs operation which is invoked
1069 * with an active reference - e.g. one of kernfs_ops. Each invocation of
1070 * this function must also be matched with an invocation of
1071 * kernfs_unbreak_active_protection().
1073 * This function releases the active reference of @kn the caller is
1074 * holding. Once this function is called, @kn may be removed at any point
1075 * and the caller is solely responsible for ensuring that the objects it
1076 * dereferences are accessible.
1078 void kernfs_break_active_protection(struct kernfs_node
*kn
)
1081 * Take out ourself out of the active ref dependency chain. If
1082 * we're called without an active ref, lockdep will complain.
1084 kernfs_put_active(kn
);
1088 * kernfs_unbreak_active_protection - undo kernfs_break_active_protection()
1089 * @kn: the self kernfs_node
1091 * If kernfs_break_active_protection() was called, this function must be
1092 * invoked before finishing the kernfs operation. Note that while this
1093 * function restores the active reference, it doesn't and can't actually
1094 * restore the active protection - @kn may already or be in the process of
1095 * being removed. Once kernfs_break_active_protection() is invoked, that
1096 * protection is irreversibly gone for the kernfs operation instance.
1098 * While this function may be called at any point after
1099 * kernfs_break_active_protection() is invoked, its most useful location
1100 * would be right before the enclosing kernfs operation returns.
1102 void kernfs_unbreak_active_protection(struct kernfs_node
*kn
)
1105 * @kn->active could be in any state; however, the increment we do
1106 * here will be undone as soon as the enclosing kernfs operation
1107 * finishes and this temporary bump can't break anything. If @kn
1108 * is alive, nothing changes. If @kn is being deactivated, the
1109 * soon-to-follow put will either finish deactivation or restore
1110 * deactivated state. If @kn is already removed, the temporary
1111 * bump is guaranteed to be gone before @kn is released.
1113 atomic_inc(&kn
->active
);
1114 if (kernfs_lockdep(kn
))
1115 rwsem_acquire(&kn
->dep_map
, 0, 1, _RET_IP_
);
1119 * kernfs_remove_self - remove a kernfs_node from its own method
1120 * @kn: the self kernfs_node to remove
1122 * The caller must be running off of a kernfs operation which is invoked
1123 * with an active reference - e.g. one of kernfs_ops. This can be used to
1124 * implement a file operation which deletes itself.
1126 * For example, the "delete" file for a sysfs device directory can be
1127 * implemented by invoking kernfs_remove_self() on the "delete" file
1128 * itself. This function breaks the circular dependency of trying to
1129 * deactivate self while holding an active ref itself. It isn't necessary
1130 * to modify the usual removal path to use kernfs_remove_self(). The
1131 * "delete" implementation can simply invoke kernfs_remove_self() on self
1132 * before proceeding with the usual removal path. kernfs will ignore later
1133 * kernfs_remove() on self.
1135 * kernfs_remove_self() can be called multiple times concurrently on the
1136 * same kernfs_node. Only the first one actually performs removal and
1137 * returns %true. All others will wait until the kernfs operation which
1138 * won self-removal finishes and return %false. Note that the losers wait
1139 * for the completion of not only the winning kernfs_remove_self() but also
1140 * the whole kernfs_ops which won the arbitration. This can be used to
1141 * guarantee, for example, all concurrent writes to a "delete" file to
1142 * finish only after the whole operation is complete.
1144 bool kernfs_remove_self(struct kernfs_node
*kn
)
1148 mutex_lock(&kernfs_mutex
);
1149 kernfs_break_active_protection(kn
);
1152 * SUICIDAL is used to arbitrate among competing invocations. Only
1153 * the first one will actually perform removal. When the removal
1154 * is complete, SUICIDED is set and the active ref is restored
1155 * while holding kernfs_mutex. The ones which lost arbitration
1156 * waits for SUICDED && drained which can happen only after the
1157 * enclosing kernfs operation which executed the winning instance
1158 * of kernfs_remove_self() finished.
1160 if (!(kn
->flags
& KERNFS_SUICIDAL
)) {
1161 kn
->flags
|= KERNFS_SUICIDAL
;
1162 __kernfs_remove(kn
);
1163 kn
->flags
|= KERNFS_SUICIDED
;
1166 wait_queue_head_t
*waitq
= &kernfs_root(kn
)->deactivate_waitq
;
1170 prepare_to_wait(waitq
, &wait
, TASK_UNINTERRUPTIBLE
);
1172 if ((kn
->flags
& KERNFS_SUICIDED
) &&
1173 atomic_read(&kn
->active
) == KN_DEACTIVATED_BIAS
)
1176 mutex_unlock(&kernfs_mutex
);
1178 mutex_lock(&kernfs_mutex
);
1180 finish_wait(waitq
, &wait
);
1181 WARN_ON_ONCE(!RB_EMPTY_NODE(&kn
->rb
));
1186 * This must be done while holding kernfs_mutex; otherwise, waiting
1187 * for SUICIDED && deactivated could finish prematurely.
1189 kernfs_unbreak_active_protection(kn
);
1191 mutex_unlock(&kernfs_mutex
);
1196 * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
1197 * @parent: parent of the target
1198 * @name: name of the kernfs_node to remove
1199 * @ns: namespace tag of the kernfs_node to remove
1201 * Look for the kernfs_node with @name and @ns under @parent and remove it.
1202 * Returns 0 on success, -ENOENT if such entry doesn't exist.
1204 int kernfs_remove_by_name_ns(struct kernfs_node
*parent
, const char *name
,
1207 struct kernfs_node
*kn
;
1210 WARN(1, KERN_WARNING
"kernfs: can not remove '%s', no directory\n",
1215 mutex_lock(&kernfs_mutex
);
1217 kn
= kernfs_find_ns(parent
, name
, ns
);
1219 __kernfs_remove(kn
);
1221 mutex_unlock(&kernfs_mutex
);
1230 * kernfs_rename_ns - move and rename a kernfs_node
1232 * @new_parent: new parent to put @sd under
1233 * @new_name: new name
1234 * @new_ns: new namespace tag
1236 int kernfs_rename_ns(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
1237 const char *new_name
, const void *new_ns
)
1239 struct kernfs_node
*old_parent
;
1240 const char *old_name
= NULL
;
1243 /* can't move or rename root */
1247 mutex_lock(&kernfs_mutex
);
1250 if (!kernfs_active(kn
) || !kernfs_active(new_parent
))
1254 if ((kn
->parent
== new_parent
) && (kn
->ns
== new_ns
) &&
1255 (strcmp(kn
->name
, new_name
) == 0))
1256 goto out
; /* nothing to rename */
1259 if (kernfs_find_ns(new_parent
, new_name
, new_ns
))
1262 /* rename kernfs_node */
1263 if (strcmp(kn
->name
, new_name
) != 0) {
1265 new_name
= kstrdup_const(new_name
, GFP_KERNEL
);
1273 * Move to the appropriate place in the appropriate directories rbtree.
1275 kernfs_unlink_sibling(kn
);
1276 kernfs_get(new_parent
);
1278 /* rename_lock protects ->parent and ->name accessors */
1279 spin_lock_irq(&kernfs_rename_lock
);
1281 old_parent
= kn
->parent
;
1282 kn
->parent
= new_parent
;
1286 old_name
= kn
->name
;
1287 kn
->name
= new_name
;
1290 spin_unlock_irq(&kernfs_rename_lock
);
1292 kn
->hash
= kernfs_name_hash(kn
->name
, kn
->ns
);
1293 kernfs_link_sibling(kn
);
1295 kernfs_put(old_parent
);
1296 kfree_const(old_name
);
1300 mutex_unlock(&kernfs_mutex
);
1304 /* Relationship between s_mode and the DT_xxx types */
1305 static inline unsigned char dt_type(struct kernfs_node
*kn
)
1307 return (kn
->mode
>> 12) & 15;
1310 static int kernfs_dir_fop_release(struct inode
*inode
, struct file
*filp
)
1312 kernfs_put(filp
->private_data
);
1316 static struct kernfs_node
*kernfs_dir_pos(const void *ns
,
1317 struct kernfs_node
*parent
, loff_t hash
, struct kernfs_node
*pos
)
1320 int valid
= kernfs_active(pos
) &&
1321 pos
->parent
== parent
&& hash
== pos
->hash
;
1326 if (!pos
&& (hash
> 1) && (hash
< INT_MAX
)) {
1327 struct rb_node
*node
= parent
->dir
.children
.rb_node
;
1329 pos
= rb_to_kn(node
);
1331 if (hash
< pos
->hash
)
1332 node
= node
->rb_left
;
1333 else if (hash
> pos
->hash
)
1334 node
= node
->rb_right
;
1339 /* Skip over entries which are dying/dead or in the wrong namespace */
1340 while (pos
&& (!kernfs_active(pos
) || pos
->ns
!= ns
)) {
1341 struct rb_node
*node
= rb_next(&pos
->rb
);
1345 pos
= rb_to_kn(node
);
1350 static struct kernfs_node
*kernfs_dir_next_pos(const void *ns
,
1351 struct kernfs_node
*parent
, ino_t ino
, struct kernfs_node
*pos
)
1353 pos
= kernfs_dir_pos(ns
, parent
, ino
, pos
);
1356 struct rb_node
*node
= rb_next(&pos
->rb
);
1360 pos
= rb_to_kn(node
);
1361 } while (pos
&& (!kernfs_active(pos
) || pos
->ns
!= ns
));
1366 static int kernfs_fop_readdir(struct file
*file
, struct dir_context
*ctx
)
1368 struct dentry
*dentry
= file
->f_path
.dentry
;
1369 struct kernfs_node
*parent
= dentry
->d_fsdata
;
1370 struct kernfs_node
*pos
= file
->private_data
;
1371 const void *ns
= NULL
;
1373 if (!dir_emit_dots(file
, ctx
))
1375 mutex_lock(&kernfs_mutex
);
1377 if (kernfs_ns_enabled(parent
))
1378 ns
= kernfs_info(dentry
->d_sb
)->ns
;
1380 for (pos
= kernfs_dir_pos(ns
, parent
, ctx
->pos
, pos
);
1382 pos
= kernfs_dir_next_pos(ns
, parent
, ctx
->pos
, pos
)) {
1383 const char *name
= pos
->name
;
1384 unsigned int type
= dt_type(pos
);
1385 int len
= strlen(name
);
1386 ino_t ino
= pos
->ino
;
1388 ctx
->pos
= pos
->hash
;
1389 file
->private_data
= pos
;
1392 mutex_unlock(&kernfs_mutex
);
1393 if (!dir_emit(ctx
, name
, len
, ino
, type
))
1395 mutex_lock(&kernfs_mutex
);
1397 mutex_unlock(&kernfs_mutex
);
1398 file
->private_data
= NULL
;
1403 static loff_t
kernfs_dir_fop_llseek(struct file
*file
, loff_t offset
,
1406 struct inode
*inode
= file_inode(file
);
1409 mutex_lock(&inode
->i_mutex
);
1410 ret
= generic_file_llseek(file
, offset
, whence
);
1411 mutex_unlock(&inode
->i_mutex
);
1416 const struct file_operations kernfs_dir_fops
= {
1417 .read
= generic_read_dir
,
1418 .iterate
= kernfs_fop_readdir
,
1419 .release
= kernfs_dir_fop_release
,
1420 .llseek
= kernfs_dir_fop_llseek
,