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);
23 #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
25 static bool kernfs_lockdep(struct kernfs_node *kn)
27 #ifdef CONFIG_DEBUG_LOCK_ALLOC
28 return kn->flags & KERNFS_LOCKDEP;
36 * @name: Null terminated string to hash
37 * @ns: Namespace tag to hash
39 * Returns 31 bit hash of ns + name (so it fits in an off_t )
41 static unsigned int kernfs_name_hash(const char *name, const void *ns)
43 unsigned long hash = init_name_hash();
44 unsigned int len = strlen(name);
46 hash = partial_name_hash(*name++, hash);
47 hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
49 /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
57 static int kernfs_name_compare(unsigned int hash, const char *name,
58 const void *ns, const struct kernfs_node *kn)
61 return hash - kn->hash;
64 return strcmp(name, kn->name);
67 static int kernfs_sd_compare(const struct kernfs_node *left,
68 const struct kernfs_node *right)
70 return kernfs_name_compare(left->hash, left->name, left->ns, right);
74 * kernfs_link_sibling - link kernfs_node into sibling rbtree
75 * @kn: kernfs_node of interest
77 * Link @kn into its sibling rbtree which starts from
78 * @kn->parent->dir.children.
81 * mutex_lock(kernfs_mutex)
84 * 0 on susccess -EEXIST on failure.
86 static int kernfs_link_sibling(struct kernfs_node *kn)
88 struct rb_node **node = &kn->parent->dir.children.rb_node;
89 struct rb_node *parent = NULL;
91 if (kernfs_type(kn) == KERNFS_DIR)
92 kn->parent->dir.subdirs++;
95 struct kernfs_node *pos;
98 pos = rb_to_kn(*node);
100 result = kernfs_sd_compare(kn, pos);
102 node = &pos->rb.rb_left;
104 node = &pos->rb.rb_right;
108 /* add new node and rebalance the tree */
109 rb_link_node(&kn->rb, parent, node);
110 rb_insert_color(&kn->rb, &kn->parent->dir.children);
115 * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
116 * @kn: kernfs_node of interest
118 * Unlink @kn from its sibling rbtree which starts from
119 * kn->parent->dir.children.
122 * mutex_lock(kernfs_mutex)
124 static bool kernfs_unlink_sibling(struct kernfs_node *kn)
126 if (RB_EMPTY_NODE(&kn->rb))
129 if (kernfs_type(kn) == KERNFS_DIR)
130 kn->parent->dir.subdirs--;
132 rb_erase(&kn->rb, &kn->parent->dir.children);
133 RB_CLEAR_NODE(&kn->rb);
138 * kernfs_get_active - get an active reference to kernfs_node
139 * @kn: kernfs_node to get an active reference to
141 * Get an active reference of @kn. This function is noop if @kn
145 * Pointer to @kn on success, NULL on failure.
147 struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
152 if (kernfs_lockdep(kn))
153 rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
156 * Try to obtain an active ref. If @kn is deactivated, we block
157 * till either it's reactivated or killed.
160 if (atomic_inc_unless_negative(&kn->active))
163 wait_event(kernfs_root(kn)->deactivate_waitq,
164 atomic_read(&kn->active) >= 0 ||
165 RB_EMPTY_NODE(&kn->rb));
166 } while (!RB_EMPTY_NODE(&kn->rb));
168 if (kernfs_lockdep(kn))
169 rwsem_release(&kn->dep_map, 1, _RET_IP_);
174 * kernfs_put_active - put an active reference to kernfs_node
175 * @kn: kernfs_node to put an active reference to
177 * Put an active reference to @kn. This function is noop if @kn
180 void kernfs_put_active(struct kernfs_node *kn)
182 struct kernfs_root *root = kernfs_root(kn);
188 if (kernfs_lockdep(kn))
189 rwsem_release(&kn->dep_map, 1, _RET_IP_);
190 v = atomic_dec_return(&kn->active);
191 if (likely(v != KN_DEACTIVATED_BIAS))
194 wake_up_all(&root->deactivate_waitq);
198 * kernfs_drain - drain kernfs_node
199 * @kn: kernfs_node to drain
201 * Drain existing usages of @kn. Mutiple removers may invoke this function
202 * concurrently on @kn and all will return after draining is complete.
203 * Returns %true if drain is performed and kernfs_mutex was temporarily
204 * released. %false if @kn was already drained and no operation was
207 * The caller is responsible for ensuring @kn stays pinned while this
208 * function is in progress even if it gets removed by someone else.
210 static bool kernfs_drain(struct kernfs_node *kn)
211 __releases(&kernfs_mutex) __acquires(&kernfs_mutex)
213 struct kernfs_root *root = kernfs_root(kn);
215 lockdep_assert_held(&kernfs_mutex);
216 WARN_ON_ONCE(atomic_read(&kn->active) >= 0);
219 * We want to go through the active ref lockdep annotation at least
220 * once for all node removals, but the lockdep annotation can't be
221 * nested inside kernfs_mutex and deactivation can't make forward
222 * progress if we keep dropping the mutex. Use JUST_ACTIVATED to
223 * force the slow path once for each deactivation if lockdep is
226 if ((!kernfs_lockdep(kn) || !(kn->flags & KERNFS_JUST_DEACTIVATED)) &&
227 atomic_read(&kn->active) == KN_DEACTIVATED_BIAS)
230 kn->flags &= ~KERNFS_JUST_DEACTIVATED;
231 mutex_unlock(&kernfs_mutex);
233 if (kernfs_lockdep(kn)) {
234 rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
235 if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
236 lock_contended(&kn->dep_map, _RET_IP_);
239 wait_event(root->deactivate_waitq,
240 atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
242 if (kernfs_lockdep(kn)) {
243 lock_acquired(&kn->dep_map, _RET_IP_);
244 rwsem_release(&kn->dep_map, 1, _RET_IP_);
247 mutex_lock(&kernfs_mutex);
252 * kernfs_get - get a reference count on a kernfs_node
253 * @kn: the target kernfs_node
255 void kernfs_get(struct kernfs_node *kn)
258 WARN_ON(!atomic_read(&kn->count));
259 atomic_inc(&kn->count);
262 EXPORT_SYMBOL_GPL(kernfs_get);
265 * kernfs_put - put a reference count on a kernfs_node
266 * @kn: the target kernfs_node
268 * Put a reference count of @kn and destroy it if it reached zero.
270 void kernfs_put(struct kernfs_node *kn)
272 struct kernfs_node *parent;
273 struct kernfs_root *root;
275 if (!kn || !atomic_dec_and_test(&kn->count))
277 root = kernfs_root(kn);
280 * Moving/renaming is always done while holding reference.
281 * kn->parent won't change beneath us.
285 WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,
286 "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
287 parent ? parent->name : "", kn->name, atomic_read(&kn->active));
289 if (kernfs_type(kn) == KERNFS_LINK)
290 kernfs_put(kn->symlink.target_kn);
291 if (!(kn->flags & KERNFS_STATIC_NAME))
294 if (kn->iattr->ia_secdata)
295 security_release_secctx(kn->iattr->ia_secdata,
296 kn->iattr->ia_secdata_len);
297 simple_xattrs_free(&kn->iattr->xattrs);
300 ida_simple_remove(&root->ino_ida, kn->ino);
301 kmem_cache_free(kernfs_node_cache, kn);
305 if (atomic_dec_and_test(&kn->count))
308 /* just released the root kn, free @root too */
309 ida_destroy(&root->ino_ida);
313 EXPORT_SYMBOL_GPL(kernfs_put);
315 static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
317 struct kernfs_node *kn;
319 if (flags & LOOKUP_RCU)
322 /* Always perform fresh lookup for negatives */
323 if (!dentry->d_inode)
324 goto out_bad_unlocked;
326 kn = dentry->d_fsdata;
327 mutex_lock(&kernfs_mutex);
329 /* Force fresh lookup if removed */
330 if (kn->parent && RB_EMPTY_NODE(&kn->rb))
333 /* The kernfs node has been moved? */
334 if (dentry->d_parent->d_fsdata != kn->parent)
337 /* The kernfs node has been renamed */
338 if (strcmp(dentry->d_name.name, kn->name) != 0)
341 /* The kernfs node has been moved to a different namespace */
342 if (kn->parent && kernfs_ns_enabled(kn->parent) &&
343 kernfs_info(dentry->d_sb)->ns != kn->ns)
346 mutex_unlock(&kernfs_mutex);
350 mutex_unlock(&kernfs_mutex);
353 * @dentry doesn't match the underlying kernfs node, drop the
354 * dentry and force lookup. If we have submounts we must allow the
355 * vfs caches to lie about the state of the filesystem to prevent
356 * leaks and other nasty things, so use check_submounts_and_drop()
357 * instead of d_drop().
359 if (check_submounts_and_drop(dentry) != 0)
365 static void kernfs_dop_release(struct dentry *dentry)
367 kernfs_put(dentry->d_fsdata);
370 const struct dentry_operations kernfs_dops = {
371 .d_revalidate = kernfs_dop_revalidate,
372 .d_release = kernfs_dop_release,
375 struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name,
376 umode_t mode, unsigned flags)
378 char *dup_name = NULL;
379 struct kernfs_node *kn;
382 if (!(flags & KERNFS_STATIC_NAME)) {
383 name = dup_name = kstrdup(name, GFP_KERNEL);
388 kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL);
392 ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL);
397 atomic_set(&kn->count, 1);
398 atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
400 RB_CLEAR_NODE(&kn->rb);
409 kmem_cache_free(kernfs_node_cache, kn);
416 * kernfs_add_one - add kernfs_node to parent without warning
417 * @kn: kernfs_node to be added
418 * @parent: the parent kernfs_node to add @kn to
420 * Get @parent and set @kn->parent to it and increment nlink of the
421 * parent inode if @kn is a directory and link into the children list
425 * 0 on success, -EEXIST if entry with the given name already
428 int kernfs_add_one(struct kernfs_node *kn, struct kernfs_node *parent)
430 struct kernfs_iattrs *ps_iattr;
434 if (!kernfs_get_active(parent))
437 mutex_lock(&kernfs_mutex);
440 has_ns = kernfs_ns_enabled(parent);
441 if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
442 has_ns ? "required" : "invalid", parent->name, kn->name))
445 if (kernfs_type(parent) != KERNFS_DIR)
448 kn->hash = kernfs_name_hash(kn->name, kn->ns);
452 ret = kernfs_link_sibling(kn);
456 /* Update timestamps on the parent */
457 ps_iattr = parent->iattr;
459 struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
460 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
463 /* Mark the entry added into directory tree */
464 atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
468 mutex_unlock(&kernfs_mutex);
469 kernfs_put_active(parent);
474 * kernfs_find_ns - find kernfs_node with the given name
475 * @parent: kernfs_node to search under
476 * @name: name to look for
477 * @ns: the namespace tag to use
479 * Look for kernfs_node with name @name under @parent. Returns pointer to
480 * the found kernfs_node on success, %NULL on failure.
482 static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent,
483 const unsigned char *name,
486 struct rb_node *node = parent->dir.children.rb_node;
487 bool has_ns = kernfs_ns_enabled(parent);
490 lockdep_assert_held(&kernfs_mutex);
492 if (has_ns != (bool)ns) {
493 WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
494 has_ns ? "required" : "invalid", parent->name, name);
498 hash = kernfs_name_hash(name, ns);
500 struct kernfs_node *kn;
504 result = kernfs_name_compare(hash, name, ns, kn);
506 node = node->rb_left;
508 node = node->rb_right;
516 * kernfs_find_and_get_ns - find and get kernfs_node with the given name
517 * @parent: kernfs_node to search under
518 * @name: name to look for
519 * @ns: the namespace tag to use
521 * Look for kernfs_node with name @name under @parent and get a reference
522 * if found. This function may sleep and returns pointer to the found
523 * kernfs_node on success, %NULL on failure.
525 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
526 const char *name, const void *ns)
528 struct kernfs_node *kn;
530 mutex_lock(&kernfs_mutex);
531 kn = kernfs_find_ns(parent, name, ns);
533 mutex_unlock(&kernfs_mutex);
537 EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
540 * kernfs_create_root - create a new kernfs hierarchy
541 * @kdops: optional directory syscall operations for the hierarchy
542 * @priv: opaque data associated with the new directory
544 * Returns the root of the new hierarchy on success, ERR_PTR() value on
547 struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv)
549 struct kernfs_root *root;
550 struct kernfs_node *kn;
552 root = kzalloc(sizeof(*root), GFP_KERNEL);
554 return ERR_PTR(-ENOMEM);
556 ida_init(&root->ino_ida);
558 kn = kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO, KERNFS_DIR);
560 ida_destroy(&root->ino_ida);
562 return ERR_PTR(-ENOMEM);
565 atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
570 root->dir_ops = kdops;
572 init_waitqueue_head(&root->deactivate_waitq);
578 * kernfs_destroy_root - destroy a kernfs hierarchy
579 * @root: root of the hierarchy to destroy
581 * Destroy the hierarchy anchored at @root by removing all existing
582 * directories and destroying @root.
584 void kernfs_destroy_root(struct kernfs_root *root)
586 kernfs_remove(root->kn); /* will also free @root */
590 * kernfs_create_dir_ns - create a directory
591 * @parent: parent in which to create a new directory
592 * @name: name of the new directory
593 * @mode: mode of the new directory
594 * @priv: opaque data associated with the new directory
595 * @ns: optional namespace tag of the directory
597 * Returns the created node on success, ERR_PTR() value on failure.
599 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
600 const char *name, umode_t mode,
601 void *priv, const void *ns)
603 struct kernfs_node *kn;
607 kn = kernfs_new_node(kernfs_root(parent), name, mode | S_IFDIR,
610 return ERR_PTR(-ENOMEM);
612 kn->dir.root = parent->dir.root;
617 rc = kernfs_add_one(kn, parent);
625 static struct dentry *kernfs_iop_lookup(struct inode *dir,
626 struct dentry *dentry,
630 struct kernfs_node *parent = dentry->d_parent->d_fsdata;
631 struct kernfs_node *kn;
633 const void *ns = NULL;
635 mutex_lock(&kernfs_mutex);
637 if (kernfs_ns_enabled(parent))
638 ns = kernfs_info(dir->i_sb)->ns;
640 kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
648 dentry->d_fsdata = kn;
650 /* attach dentry and inode */
651 inode = kernfs_get_inode(dir->i_sb, kn);
653 ret = ERR_PTR(-ENOMEM);
657 /* instantiate and hash dentry */
658 ret = d_materialise_unique(dentry, inode);
660 mutex_unlock(&kernfs_mutex);
664 static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry,
667 struct kernfs_node *parent = dir->i_private;
668 struct kernfs_dir_ops *kdops = kernfs_root(parent)->dir_ops;
670 if (!kdops || !kdops->mkdir)
673 return kdops->mkdir(parent, dentry->d_name.name, mode);
676 static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry)
678 struct kernfs_node *kn = dentry->d_fsdata;
679 struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops;
681 if (!kdops || !kdops->rmdir)
684 return kdops->rmdir(kn);
687 static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry,
688 struct inode *new_dir, struct dentry *new_dentry)
690 struct kernfs_node *kn = old_dentry->d_fsdata;
691 struct kernfs_node *new_parent = new_dir->i_private;
692 struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops;
694 if (!kdops || !kdops->rename)
697 return kdops->rename(kn, new_parent, new_dentry->d_name.name);
700 const struct inode_operations kernfs_dir_iops = {
701 .lookup = kernfs_iop_lookup,
702 .permission = kernfs_iop_permission,
703 .setattr = kernfs_iop_setattr,
704 .getattr = kernfs_iop_getattr,
705 .setxattr = kernfs_iop_setxattr,
706 .removexattr = kernfs_iop_removexattr,
707 .getxattr = kernfs_iop_getxattr,
708 .listxattr = kernfs_iop_listxattr,
710 .mkdir = kernfs_iop_mkdir,
711 .rmdir = kernfs_iop_rmdir,
712 .rename = kernfs_iop_rename,
715 static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos)
717 struct kernfs_node *last;
724 if (kernfs_type(pos) != KERNFS_DIR)
727 rbn = rb_first(&pos->dir.children);
738 * kernfs_next_descendant_post - find the next descendant for post-order walk
739 * @pos: the current position (%NULL to initiate traversal)
740 * @root: kernfs_node whose descendants to walk
742 * Find the next descendant to visit for post-order traversal of @root's
743 * descendants. @root is included in the iteration and the last node to be
746 static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
747 struct kernfs_node *root)
751 lockdep_assert_held(&kernfs_mutex);
753 /* if first iteration, visit leftmost descendant which may be root */
755 return kernfs_leftmost_descendant(root);
757 /* if we visited @root, we're done */
761 /* if there's an unvisited sibling, visit its leftmost descendant */
762 rbn = rb_next(&pos->rb);
764 return kernfs_leftmost_descendant(rb_to_kn(rbn));
766 /* no sibling left, visit parent */
770 static void __kernfs_deactivate(struct kernfs_node *kn)
772 struct kernfs_node *pos;
774 lockdep_assert_held(&kernfs_mutex);
776 /* prevent any new usage under @kn by deactivating all nodes */
778 while ((pos = kernfs_next_descendant_post(pos, kn))) {
779 if (!pos->deact_depth++) {
780 WARN_ON_ONCE(atomic_read(&pos->active) < 0);
781 atomic_add(KN_DEACTIVATED_BIAS, &pos->active);
782 pos->flags |= KERNFS_JUST_DEACTIVATED;
787 * Drain the subtree. If kernfs_drain() blocked to drain, which is
788 * indicated by %true return, it temporarily released kernfs_mutex
789 * and the rbtree might have been modified inbetween breaking our
790 * future walk. Restart the walk after each %true return.
793 while ((pos = kernfs_next_descendant_post(pos, kn))) {
797 drained = kernfs_drain(pos);
804 static void __kernfs_reactivate(struct kernfs_node *kn)
806 struct kernfs_node *pos;
808 lockdep_assert_held(&kernfs_mutex);
811 while ((pos = kernfs_next_descendant_post(pos, kn))) {
812 if (!--pos->deact_depth) {
813 WARN_ON_ONCE(atomic_read(&pos->active) >= 0);
814 atomic_sub(KN_DEACTIVATED_BIAS, &pos->active);
816 WARN_ON_ONCE(pos->deact_depth < 0);
819 /* some nodes reactivated, kick get_active waiters */
820 wake_up_all(&kernfs_root(kn)->deactivate_waitq);
823 static void __kernfs_deactivate_self(struct kernfs_node *kn)
826 * Take out ourself out of the active ref dependency chain and
827 * deactivate. If we're called without an active ref, lockdep will
830 kernfs_put_active(kn);
831 __kernfs_deactivate(kn);
834 static void __kernfs_reactivate_self(struct kernfs_node *kn)
836 __kernfs_reactivate(kn);
838 * Restore active ref dropped by deactivate_self() so that it's
839 * balanced on return. put_active() will soon be called on @kn, so
840 * this can't break anything regardless of @kn's state.
842 atomic_inc(&kn->active);
843 if (kernfs_lockdep(kn))
844 rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_);
848 * kernfs_deactivate - deactivate subtree of a node
849 * @kn: kernfs_node to deactivate subtree of
851 * Deactivate the subtree of @kn. On return, there's no active operation
852 * going on under @kn and creation or renaming of a node under @kn is
853 * blocked until @kn is reactivated or removed. This function can be
854 * called multiple times and nests properly. Each invocation should be
855 * paired with kernfs_reactivate().
857 * For a kernfs user which uses simple locking, the subsystem lock would
858 * nest inside active reference. This becomes problematic if the user
859 * tries to remove nodes while holding the subystem lock as it would create
860 * a reverse locking dependency from the subsystem lock to active ref.
861 * This function can be used to break such reverse dependency. The user
862 * can call this function outside the subsystem lock and then proceed to
863 * invoke kernfs_remove() while holding the subsystem lock without
864 * introducing such reverse dependency.
866 void kernfs_deactivate(struct kernfs_node *kn)
868 mutex_lock(&kernfs_mutex);
869 __kernfs_deactivate(kn);
870 mutex_unlock(&kernfs_mutex);
874 * kernfs_reactivate - reactivate subtree of a node
875 * @kn: kernfs_node to reactivate subtree of
877 * Undo kernfs_deactivate().
879 void kernfs_reactivate(struct kernfs_node *kn)
881 mutex_lock(&kernfs_mutex);
882 __kernfs_reactivate(kn);
883 mutex_unlock(&kernfs_mutex);
887 * kernfs_deactivate_self - deactivate subtree of a node from its own method
888 * @kn: the self kernfs_node to deactivate subtree of
890 * The caller must be running off of a kernfs operation which is invoked
891 * with an active reference - e.g. one of kernfs_ops. Once this function
892 * is called, @kn may be removed by someone else while the enclosing method
893 * is in progress. Other than that, this function is equivalent to
894 * kernfs_deactivate() and should be paired with kernfs_reactivate_self().
896 void kernfs_deactivate_self(struct kernfs_node *kn)
898 mutex_lock(&kernfs_mutex);
899 __kernfs_deactivate_self(kn);
900 mutex_unlock(&kernfs_mutex);
904 * kernfs_reactivate_self - reactivate subtree of a node from its own method
905 * @kn: the self kernfs_node to reactivate subtree of
907 * Undo kernfs_deactivate_self().
909 void kernfs_reactivate_self(struct kernfs_node *kn)
911 mutex_lock(&kernfs_mutex);
912 __kernfs_reactivate_self(kn);
913 mutex_unlock(&kernfs_mutex);
916 static void __kernfs_remove(struct kernfs_node *kn)
918 struct kernfs_root *root = kernfs_root(kn);
919 struct kernfs_node *pos;
921 lockdep_assert_held(&kernfs_mutex);
926 pr_debug("kernfs %s: removing\n", kn->name);
928 __kernfs_deactivate(kn);
930 /* unlink the subtree node-by-node */
932 pos = kernfs_leftmost_descendant(kn);
935 * We're gonna release kernfs_mutex to unmap bin files,
936 * Make sure @pos doesn't go away inbetween.
941 * This must be come before unlinking; otherwise, when
942 * there are multiple removers, some may finish before
943 * unmapping is complete.
945 if (pos->flags & KERNFS_HAS_MMAP) {
946 mutex_unlock(&kernfs_mutex);
947 kernfs_unmap_file(pos);
948 mutex_lock(&kernfs_mutex);
952 * kernfs_unlink_sibling() succeeds once per node. Use it
953 * to decide who's responsible for cleanups.
955 if (!pos->parent || kernfs_unlink_sibling(pos)) {
956 struct kernfs_iattrs *ps_iattr =
957 pos->parent ? pos->parent->iattr : NULL;
959 /* update timestamps on the parent */
961 ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME;
962 ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
971 /* some nodes killed, kick get_active waiters */
972 wake_up_all(&root->deactivate_waitq);
976 * kernfs_remove - remove a kernfs_node recursively
977 * @kn: the kernfs_node to remove
979 * Remove @kn along with all its subdirectories and files.
981 void kernfs_remove(struct kernfs_node *kn)
983 mutex_lock(&kernfs_mutex);
985 mutex_unlock(&kernfs_mutex);
989 * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
990 * @parent: parent of the target
991 * @name: name of the kernfs_node to remove
992 * @ns: namespace tag of the kernfs_node to remove
994 * Look for the kernfs_node with @name and @ns under @parent and remove it.
995 * Returns 0 on success, -ENOENT if such entry doesn't exist.
997 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
1000 struct kernfs_node *kn;
1003 WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n",
1008 mutex_lock(&kernfs_mutex);
1010 kn = kernfs_find_ns(parent, name, ns);
1012 __kernfs_remove(kn);
1014 mutex_unlock(&kernfs_mutex);
1023 * kernfs_rename_ns - move and rename a kernfs_node
1025 * @new_parent: new parent to put @sd under
1026 * @new_name: new name
1027 * @new_ns: new namespace tag
1029 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
1030 const char *new_name, const void *new_ns)
1035 if (!kernfs_get_active(new_parent))
1037 if (!kernfs_get_active(kn))
1038 goto out_put_new_parent;
1040 mutex_lock(&kernfs_mutex);
1043 if ((kn->parent == new_parent) && (kn->ns == new_ns) &&
1044 (strcmp(kn->name, new_name) == 0))
1045 goto out_unlock; /* nothing to rename */
1048 if (kernfs_find_ns(new_parent, new_name, new_ns))
1051 /* rename kernfs_node */
1052 if (strcmp(kn->name, new_name) != 0) {
1054 new_name = kstrdup(new_name, GFP_KERNEL);
1058 if (kn->flags & KERNFS_STATIC_NAME)
1059 kn->flags &= ~KERNFS_STATIC_NAME;
1063 kn->name = new_name;
1067 * Move to the appropriate place in the appropriate directories rbtree.
1069 kernfs_unlink_sibling(kn);
1070 kernfs_get(new_parent);
1071 kernfs_put(kn->parent);
1073 kn->hash = kernfs_name_hash(kn->name, kn->ns);
1074 kn->parent = new_parent;
1075 kernfs_link_sibling(kn);
1079 mutex_unlock(&kernfs_mutex);
1080 kernfs_put_active(kn);
1082 kernfs_put_active(new_parent);
1087 /* Relationship between s_mode and the DT_xxx types */
1088 static inline unsigned char dt_type(struct kernfs_node *kn)
1090 return (kn->mode >> 12) & 15;
1093 static int kernfs_dir_fop_release(struct inode *inode, struct file *filp)
1095 kernfs_put(filp->private_data);
1099 static struct kernfs_node *kernfs_dir_pos(const void *ns,
1100 struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)
1103 int valid = pos->parent == parent && hash == pos->hash;
1108 if (!pos && (hash > 1) && (hash < INT_MAX)) {
1109 struct rb_node *node = parent->dir.children.rb_node;
1111 pos = rb_to_kn(node);
1113 if (hash < pos->hash)
1114 node = node->rb_left;
1115 else if (hash > pos->hash)
1116 node = node->rb_right;
1121 /* Skip over entries in the wrong namespace */
1122 while (pos && pos->ns != ns) {
1123 struct rb_node *node = rb_next(&pos->rb);
1127 pos = rb_to_kn(node);
1132 static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
1133 struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos)
1135 pos = kernfs_dir_pos(ns, parent, ino, pos);
1138 struct rb_node *node = rb_next(&pos->rb);
1142 pos = rb_to_kn(node);
1143 } while (pos && pos->ns != ns);
1147 static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
1149 struct dentry *dentry = file->f_path.dentry;
1150 struct kernfs_node *parent = dentry->d_fsdata;
1151 struct kernfs_node *pos = file->private_data;
1152 const void *ns = NULL;
1154 if (!dir_emit_dots(file, ctx))
1156 mutex_lock(&kernfs_mutex);
1158 if (kernfs_ns_enabled(parent))
1159 ns = kernfs_info(dentry->d_sb)->ns;
1161 for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos);
1163 pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) {
1164 const char *name = pos->name;
1165 unsigned int type = dt_type(pos);
1166 int len = strlen(name);
1167 ino_t ino = pos->ino;
1169 ctx->pos = pos->hash;
1170 file->private_data = pos;
1173 mutex_unlock(&kernfs_mutex);
1174 if (!dir_emit(ctx, name, len, ino, type))
1176 mutex_lock(&kernfs_mutex);
1178 mutex_unlock(&kernfs_mutex);
1179 file->private_data = NULL;
1184 static loff_t kernfs_dir_fop_llseek(struct file *file, loff_t offset,
1187 struct inode *inode = file_inode(file);
1190 mutex_lock(&inode->i_mutex);
1191 ret = generic_file_llseek(file, offset, whence);
1192 mutex_unlock(&inode->i_mutex);
1197 const struct file_operations kernfs_dir_fops = {
1198 .read = generic_read_dir,
1199 .iterate = kernfs_fop_readdir,
1200 .release = kernfs_dir_fop_release,
1201 .llseek = kernfs_dir_fop_llseek,