1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* -*- mode: c; c-basic-offset: 8; -*-
3 * vim: noexpandtab sw=8 ts=8 sts=0:
5 * dir.c - Operations for configfs directories.
8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
10 * configfs Copyright (C) 2005 Oracle. All rights reserved.
16 #include <linux/fsnotify.h>
17 #include <linux/mount.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
20 #include <linux/err.h>
22 #include <linux/configfs.h>
23 #include "configfs_internal.h"
25 DECLARE_RWSEM(configfs_rename_sem);
27 * Protects mutations of configfs_dirent linkage together with proper i_mutex
28 * Also protects mutations of symlinks linkage to target configfs_dirent
29 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
30 * and configfs_dirent_lock locked, in that order.
31 * This allows one to safely traverse configfs_dirent trees and symlinks without
32 * having to lock inodes.
34 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
35 * unlocked is not reliable unless in detach_groups() called from
36 * rmdir()/unregister() and from configfs_attach_group()
38 DEFINE_SPINLOCK(configfs_dirent_lock);
40 static void configfs_d_iput(struct dentry * dentry,
43 struct configfs_dirent *sd = dentry->d_fsdata;
46 /* Coordinate with configfs_readdir */
47 spin_lock(&configfs_dirent_lock);
49 * Set sd->s_dentry to null only when this dentry is the one
50 * that is going to be killed. Otherwise configfs_d_iput may
51 * run just after configfs_attach_attr and set sd->s_dentry to
52 * NULL even it's still in use.
54 if (sd->s_dentry == dentry)
57 spin_unlock(&configfs_dirent_lock);
63 const struct dentry_operations configfs_dentry_ops = {
64 .d_iput = configfs_d_iput,
65 .d_delete = always_delete_dentry,
71 * Helpers to make lockdep happy with our recursive locking of default groups'
72 * inodes (see configfs_attach_group() and configfs_detach_group()).
73 * We put default groups i_mutexes in separate classes according to their depth
74 * from the youngest non-default group ancestor.
76 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
77 * groups A/B and A/C will have their inode's mutex in class
78 * default_group_class[0], and default group A/C/D will be in
79 * default_group_class[1].
81 * The lock classes are declared and assigned in inode.c, according to the
83 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
84 * default groups, and reset to -1 when all default groups are attached. During
85 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
86 * inode's mutex is set to default_group_class[s_depth - 1].
89 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
94 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
95 struct configfs_dirent *sd)
97 int parent_depth = parent_sd->s_depth;
99 if (parent_depth >= 0)
100 sd->s_depth = parent_depth + 1;
104 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
107 * item's i_mutex class is already setup, so s_depth is now only
108 * used to set new sub-directories s_depth, which is always done
109 * with item's i_mutex locked.
112 * sd->s_depth == -1 iff we are a non default group.
113 * else (we are a default group) sd->s_depth > 0 (see
116 if (sd->s_depth == -1)
118 * We are a non default group and we are going to create
125 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
127 /* We will not create default groups anymore. */
131 #else /* CONFIG_LOCKDEP */
133 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
137 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
138 struct configfs_dirent *sd)
143 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
148 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
152 #endif /* CONFIG_LOCKDEP */
155 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
157 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
158 void *element, int type)
160 struct configfs_dirent * sd;
162 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
164 return ERR_PTR(-ENOMEM);
166 atomic_set(&sd->s_count, 1);
167 INIT_LIST_HEAD(&sd->s_links);
168 INIT_LIST_HEAD(&sd->s_children);
169 sd->s_element = element;
171 configfs_init_dirent_depth(sd);
172 spin_lock(&configfs_dirent_lock);
173 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
174 spin_unlock(&configfs_dirent_lock);
175 kmem_cache_free(configfs_dir_cachep, sd);
176 return ERR_PTR(-ENOENT);
178 list_add(&sd->s_sibling, &parent_sd->s_children);
179 spin_unlock(&configfs_dirent_lock);
186 * Return -EEXIST if there is already a configfs element with the same
187 * name for the same parent.
189 * called with parent inode's i_mutex held
191 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
192 const unsigned char *new)
194 struct configfs_dirent * sd;
196 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
198 const unsigned char *existing = configfs_get_name(sd);
199 if (strcmp(existing, new))
210 int configfs_make_dirent(struct configfs_dirent * parent_sd,
211 struct dentry * dentry, void * element,
212 umode_t mode, int type)
214 struct configfs_dirent * sd;
216 sd = configfs_new_dirent(parent_sd, element, type);
221 sd->s_dentry = dentry;
223 dentry->d_fsdata = configfs_get(sd);
228 static void init_dir(struct inode * inode)
230 inode->i_op = &configfs_dir_inode_operations;
231 inode->i_fop = &configfs_dir_operations;
233 /* directory inodes start off with i_nlink == 2 (for "." entry) */
237 static void configfs_init_file(struct inode * inode)
239 inode->i_size = PAGE_SIZE;
240 inode->i_fop = &configfs_file_operations;
243 static void configfs_init_bin_file(struct inode *inode)
246 inode->i_fop = &configfs_bin_file_operations;
249 static void init_symlink(struct inode * inode)
251 inode->i_op = &configfs_symlink_inode_operations;
255 * configfs_create_dir - create a directory for an config_item.
256 * @item: config_itemwe're creating directory for.
257 * @dentry: config_item's dentry.
259 * Note: user-created entries won't be allowed under this new directory
260 * until it is validated by configfs_dir_set_ready()
263 static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
266 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
267 struct dentry *p = dentry->d_parent;
271 error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
275 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
276 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
280 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
281 error = configfs_create(dentry, mode, init_dir);
283 inc_nlink(d_inode(p));
284 item->ci_dentry = dentry;
286 struct configfs_dirent *sd = dentry->d_fsdata;
288 spin_lock(&configfs_dirent_lock);
289 list_del_init(&sd->s_sibling);
290 spin_unlock(&configfs_dirent_lock);
298 * Allow userspace to create new entries under a new directory created with
299 * configfs_create_dir(), and under all of its chidlren directories recursively.
300 * @sd configfs_dirent of the new directory to validate
302 * Caller must hold configfs_dirent_lock.
304 static void configfs_dir_set_ready(struct configfs_dirent *sd)
306 struct configfs_dirent *child_sd;
308 sd->s_type &= ~CONFIGFS_USET_CREATING;
309 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
310 if (child_sd->s_type & CONFIGFS_USET_CREATING)
311 configfs_dir_set_ready(child_sd);
315 * Check that a directory does not belong to a directory hierarchy being
316 * attached and not validated yet.
317 * @sd configfs_dirent of the directory to check
319 * @return non-zero iff the directory was validated
321 * Note: takes configfs_dirent_lock, so the result may change from false to true
322 * in two consecutive calls, but never from true to false.
324 int configfs_dirent_is_ready(struct configfs_dirent *sd)
328 spin_lock(&configfs_dirent_lock);
329 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
330 spin_unlock(&configfs_dirent_lock);
335 int configfs_create_link(struct configfs_symlink *sl,
336 struct dentry *parent,
337 struct dentry *dentry)
340 umode_t mode = S_IFLNK | S_IRWXUGO;
342 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
345 err = configfs_create(dentry, mode, init_symlink);
347 struct configfs_dirent *sd = dentry->d_fsdata;
349 spin_lock(&configfs_dirent_lock);
350 list_del_init(&sd->s_sibling);
351 spin_unlock(&configfs_dirent_lock);
359 static void remove_dir(struct dentry * d)
361 struct dentry * parent = dget(d->d_parent);
362 struct configfs_dirent * sd;
365 spin_lock(&configfs_dirent_lock);
366 list_del_init(&sd->s_sibling);
367 spin_unlock(&configfs_dirent_lock);
369 if (d_really_is_positive(d))
370 simple_rmdir(d_inode(parent),d);
372 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
378 * configfs_remove_dir - remove an config_item's directory.
379 * @item: config_item we're removing.
381 * The only thing special about this is that we remove any files in
382 * the directory before we remove the directory, and we've inlined
383 * what used to be configfs_rmdir() below, instead of calling separately.
385 * Caller holds the mutex of the item's inode
388 static void configfs_remove_dir(struct config_item * item)
390 struct dentry * dentry = dget(item->ci_dentry);
397 * Drop reference from dget() on entrance.
403 /* attaches attribute's configfs_dirent to the dentry corresponding to the
406 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
408 struct configfs_attribute * attr = sd->s_element;
411 spin_lock(&configfs_dirent_lock);
412 dentry->d_fsdata = configfs_get(sd);
413 sd->s_dentry = dentry;
414 spin_unlock(&configfs_dirent_lock);
416 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
417 (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) ?
418 configfs_init_bin_file :
425 static struct dentry * configfs_lookup(struct inode *dir,
426 struct dentry *dentry,
429 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
430 struct configfs_dirent * sd;
435 * Fake invisibility if dir belongs to a group/default groups hierarchy
438 * This forbids userspace to read/write attributes of items which may
439 * not complete their initialization, since the dentries of the
440 * attributes won't be instantiated.
443 if (!configfs_dirent_is_ready(parent_sd))
446 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
447 if (sd->s_type & CONFIGFS_NOT_PINNED) {
448 const unsigned char * name = configfs_get_name(sd);
450 if (strcmp(name, dentry->d_name.name))
454 err = configfs_attach_attr(sd, dentry);
461 * If it doesn't exist and it isn't a NOT_PINNED item,
462 * it must be negative.
464 if (dentry->d_name.len > NAME_MAX)
465 return ERR_PTR(-ENAMETOOLONG);
475 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
476 * attributes and are removed by rmdir(). We recurse, setting
477 * CONFIGFS_USET_DROPPING on all children that are candidates for
479 * If there is an error, the caller will reset the flags via
480 * configfs_detach_rollback().
482 static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait)
484 struct configfs_dirent *parent_sd = dentry->d_fsdata;
485 struct configfs_dirent *sd;
488 /* Mark that we're trying to drop the group */
489 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
492 if (!list_empty(&parent_sd->s_links))
496 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
497 if (!sd->s_element ||
498 (sd->s_type & CONFIGFS_NOT_PINNED))
500 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
501 /* Abort if racing with mkdir() */
502 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
504 *wait= dget(sd->s_dentry);
509 * Yup, recursive. If there's a problem, blame
510 * deep nesting of default_groups
512 ret = configfs_detach_prep(sd->s_dentry, wait);
526 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
529 static void configfs_detach_rollback(struct dentry *dentry)
531 struct configfs_dirent *parent_sd = dentry->d_fsdata;
532 struct configfs_dirent *sd;
534 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
536 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
537 if (sd->s_type & CONFIGFS_USET_DEFAULT)
538 configfs_detach_rollback(sd->s_dentry);
541 static void detach_attrs(struct config_item * item)
543 struct dentry * dentry = dget(item->ci_dentry);
544 struct configfs_dirent * parent_sd;
545 struct configfs_dirent * sd, * tmp;
550 pr_debug("configfs %s: dropping attrs for dir\n",
551 dentry->d_name.name);
553 parent_sd = dentry->d_fsdata;
554 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
555 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
557 spin_lock(&configfs_dirent_lock);
558 list_del_init(&sd->s_sibling);
559 spin_unlock(&configfs_dirent_lock);
560 configfs_drop_dentry(sd, dentry);
565 * Drop reference from dget() on entrance.
570 static int populate_attrs(struct config_item *item)
572 const struct config_item_type *t = item->ci_type;
573 struct configfs_attribute *attr;
574 struct configfs_bin_attribute *bin_attr;
581 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
582 if ((error = configfs_create_file(item, attr)))
586 if (t->ct_bin_attrs) {
587 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
588 error = configfs_create_bin_file(item, bin_attr);
600 static int configfs_attach_group(struct config_item *parent_item,
601 struct config_item *item,
602 struct dentry *dentry);
603 static void configfs_detach_group(struct config_item *item);
605 static void detach_groups(struct config_group *group)
607 struct dentry * dentry = dget(group->cg_item.ci_dentry);
608 struct dentry *child;
609 struct configfs_dirent *parent_sd;
610 struct configfs_dirent *sd, *tmp;
615 parent_sd = dentry->d_fsdata;
616 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
617 if (!sd->s_element ||
618 !(sd->s_type & CONFIGFS_USET_DEFAULT))
621 child = sd->s_dentry;
623 inode_lock(d_inode(child));
625 configfs_detach_group(sd->s_element);
626 d_inode(child)->i_flags |= S_DEAD;
629 inode_unlock(d_inode(child));
636 * Drop reference from dget() on entrance.
642 * This fakes mkdir(2) on a default_groups[] entry. It
643 * creates a dentry, attachs it, and then does fixup
646 * We could, perhaps, tweak our parent's ->mkdir for a minute and
647 * try using vfs_mkdir. Just a thought.
649 static int create_default_group(struct config_group *parent_group,
650 struct config_group *group)
653 struct configfs_dirent *sd;
654 /* We trust the caller holds a reference to parent */
655 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
657 if (!group->cg_item.ci_name)
658 group->cg_item.ci_name = group->cg_item.ci_namebuf;
661 child = d_alloc_name(parent, group->cg_item.ci_name);
665 ret = configfs_attach_group(&parent_group->cg_item,
666 &group->cg_item, child);
668 sd = child->d_fsdata;
669 sd->s_type |= CONFIGFS_USET_DEFAULT;
671 BUG_ON(d_inode(child));
680 static int populate_groups(struct config_group *group)
682 struct config_group *new_group;
685 list_for_each_entry(new_group, &group->default_groups, group_entry) {
686 ret = create_default_group(group, new_group);
688 detach_groups(group);
696 void configfs_remove_default_groups(struct config_group *group)
698 struct config_group *g, *n;
700 list_for_each_entry_safe(g, n, &group->default_groups, group_entry) {
701 list_del(&g->group_entry);
702 config_item_put(&g->cg_item);
705 EXPORT_SYMBOL(configfs_remove_default_groups);
708 * All of link_obj/unlink_obj/link_group/unlink_group require that
709 * subsys->su_mutex is held.
712 static void unlink_obj(struct config_item *item)
714 struct config_group *group;
716 group = item->ci_group;
718 list_del_init(&item->ci_entry);
720 item->ci_group = NULL;
721 item->ci_parent = NULL;
723 /* Drop the reference for ci_entry */
724 config_item_put(item);
726 /* Drop the reference for ci_parent */
727 config_group_put(group);
731 static void link_obj(struct config_item *parent_item, struct config_item *item)
734 * Parent seems redundant with group, but it makes certain
735 * traversals much nicer.
737 item->ci_parent = parent_item;
740 * We hold a reference on the parent for the child's ci_parent
743 item->ci_group = config_group_get(to_config_group(parent_item));
744 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
747 * We hold a reference on the child for ci_entry on the parent's
750 config_item_get(item);
753 static void unlink_group(struct config_group *group)
755 struct config_group *new_group;
757 list_for_each_entry(new_group, &group->default_groups, group_entry)
758 unlink_group(new_group);
760 group->cg_subsys = NULL;
761 unlink_obj(&group->cg_item);
764 static void link_group(struct config_group *parent_group, struct config_group *group)
766 struct config_group *new_group;
767 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
769 link_obj(&parent_group->cg_item, &group->cg_item);
771 if (parent_group->cg_subsys)
772 subsys = parent_group->cg_subsys;
773 else if (configfs_is_root(&parent_group->cg_item))
774 subsys = to_configfs_subsystem(group);
777 group->cg_subsys = subsys;
779 list_for_each_entry(new_group, &group->default_groups, group_entry)
780 link_group(group, new_group);
784 * The goal is that configfs_attach_item() (and
785 * configfs_attach_group()) can be called from either the VFS or this
786 * module. That is, they assume that the items have been created,
787 * the dentry allocated, and the dcache is all ready to go.
789 * If they fail, they must clean up after themselves as if they
790 * had never been called. The caller (VFS or local function) will
791 * handle cleaning up the dcache bits.
793 * configfs_detach_group() and configfs_detach_item() behave similarly on
794 * the way out. They assume that the proper semaphores are held, they
795 * clean up the configfs items, and they expect their callers will
796 * handle the dcache bits.
798 static int configfs_attach_item(struct config_item *parent_item,
799 struct config_item *item,
800 struct dentry *dentry)
804 ret = configfs_create_dir(item, dentry);
806 ret = populate_attrs(item);
809 * We are going to remove an inode and its dentry but
810 * the VFS may already have hit and used them. Thus,
811 * we must lock them as rmdir() would.
813 inode_lock(d_inode(dentry));
814 configfs_remove_dir(item);
815 d_inode(dentry)->i_flags |= S_DEAD;
817 inode_unlock(d_inode(dentry));
825 /* Caller holds the mutex of the item's inode */
826 static void configfs_detach_item(struct config_item *item)
829 configfs_remove_dir(item);
832 static int configfs_attach_group(struct config_item *parent_item,
833 struct config_item *item,
834 struct dentry *dentry)
837 struct configfs_dirent *sd;
839 ret = configfs_attach_item(parent_item, item, dentry);
841 sd = dentry->d_fsdata;
842 sd->s_type |= CONFIGFS_USET_DIR;
845 * FYI, we're faking mkdir in populate_groups()
846 * We must lock the group's inode to avoid races with the VFS
847 * which can already hit the inode and try to add/remove entries
850 * We must also lock the inode to remove it safely in case of
851 * error, as rmdir() would.
853 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
854 configfs_adjust_dir_dirent_depth_before_populate(sd);
855 ret = populate_groups(to_config_group(item));
857 configfs_detach_item(item);
858 d_inode(dentry)->i_flags |= S_DEAD;
861 configfs_adjust_dir_dirent_depth_after_populate(sd);
862 inode_unlock(d_inode(dentry));
870 /* Caller holds the mutex of the group's inode */
871 static void configfs_detach_group(struct config_item *item)
873 detach_groups(to_config_group(item));
874 configfs_detach_item(item);
878 * After the item has been detached from the filesystem view, we are
879 * ready to tear it out of the hierarchy. Notify the client before
880 * we do that so they can perform any cleanup that requires
881 * navigating the hierarchy. A client does not need to provide this
882 * callback. The subsystem semaphore MUST be held by the caller, and
883 * references must be valid for both items. It also assumes the
884 * caller has validated ci_type.
886 static void client_disconnect_notify(struct config_item *parent_item,
887 struct config_item *item)
889 const struct config_item_type *type;
891 type = parent_item->ci_type;
894 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
895 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
900 * Drop the initial reference from make_item()/make_group()
901 * This function assumes that reference is held on item
902 * and that item holds a valid reference to the parent. Also, it
903 * assumes the caller has validated ci_type.
905 static void client_drop_item(struct config_item *parent_item,
906 struct config_item *item)
908 const struct config_item_type *type;
910 type = parent_item->ci_type;
914 * If ->drop_item() exists, it is responsible for the
917 if (type->ct_group_ops && type->ct_group_ops->drop_item)
918 type->ct_group_ops->drop_item(to_config_group(parent_item),
921 config_item_put(item);
925 static void configfs_dump_one(struct configfs_dirent *sd, int level)
927 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
929 #define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type);
930 type_print(CONFIGFS_ROOT);
931 type_print(CONFIGFS_DIR);
932 type_print(CONFIGFS_ITEM_ATTR);
933 type_print(CONFIGFS_ITEM_LINK);
934 type_print(CONFIGFS_USET_DIR);
935 type_print(CONFIGFS_USET_DEFAULT);
936 type_print(CONFIGFS_USET_DROPPING);
940 static int configfs_dump(struct configfs_dirent *sd, int level)
942 struct configfs_dirent *child_sd;
945 configfs_dump_one(sd, level);
947 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
950 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
951 ret = configfs_dump(child_sd, level + 2);
962 * configfs_depend_item() and configfs_undepend_item()
964 * WARNING: Do not call these from a configfs callback!
966 * This describes these functions and their helpers.
968 * Allow another kernel system to depend on a config_item. If this
969 * happens, the item cannot go away until the dependent can live without
970 * it. The idea is to give client modules as simple an interface as
971 * possible. When a system asks them to depend on an item, they just
972 * call configfs_depend_item(). If the item is live and the client
973 * driver is in good shape, we'll happily do the work for them.
975 * Why is the locking complex? Because configfs uses the VFS to handle
976 * all locking, but this function is called outside the normal
977 * VFS->configfs path. So it must take VFS locks to prevent the
978 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
979 * why you can't call these functions underneath configfs callbacks.
981 * Note, btw, that this can be called at *any* time, even when a configfs
982 * subsystem isn't registered, or when configfs is loading or unloading.
983 * Just like configfs_register_subsystem(). So we take the same
984 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
985 * If we can find the target item in the
986 * configfs tree, it must be part of the subsystem tree as well, so we
987 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
988 * locking out mkdir() and rmdir(), who might be racing us.
992 * configfs_depend_prep()
994 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
995 * attributes. This is similar but not the same to configfs_detach_prep().
996 * Note that configfs_detach_prep() expects the parent to be locked when it
997 * is called, but we lock the parent *inside* configfs_depend_prep(). We
998 * do that so we can unlock it if we find nothing.
1000 * Here we do a depth-first search of the dentry hierarchy looking for
1002 * We deliberately ignore items tagged as dropping since they are virtually
1003 * dead, as well as items in the middle of attachment since they virtually
1004 * do not exist yet. This completes the locking out of racing mkdir() and
1006 * Note: subdirectories in the middle of attachment start with s_type =
1007 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1008 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1009 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1011 * If the target is not found, -ENOENT is bubbled up.
1013 * This adds a requirement that all config_items be unique!
1015 * This is recursive. There isn't
1016 * much on the stack, though, so folks that need this function - be careful
1017 * about your stack! Patches will be accepted to make it iterative.
1019 static int configfs_depend_prep(struct dentry *origin,
1020 struct config_item *target)
1022 struct configfs_dirent *child_sd, *sd;
1025 BUG_ON(!origin || !origin->d_fsdata);
1026 sd = origin->d_fsdata;
1028 if (sd->s_element == target) /* Boo-yah */
1031 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1032 if ((child_sd->s_type & CONFIGFS_DIR) &&
1033 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1034 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1035 ret = configfs_depend_prep(child_sd->s_dentry,
1038 goto out; /* Child path boo-yah */
1042 /* We looped all our children and didn't find target */
1049 static int configfs_do_depend_item(struct dentry *subsys_dentry,
1050 struct config_item *target)
1052 struct configfs_dirent *p;
1055 spin_lock(&configfs_dirent_lock);
1056 /* Scan the tree, return 0 if found */
1057 ret = configfs_depend_prep(subsys_dentry, target);
1059 goto out_unlock_dirent_lock;
1062 * We are sure that the item is not about to be removed by rmdir(), and
1063 * not in the middle of attachment by mkdir().
1065 p = target->ci_dentry->d_fsdata;
1066 p->s_dependent_count += 1;
1068 out_unlock_dirent_lock:
1069 spin_unlock(&configfs_dirent_lock);
1074 static inline struct configfs_dirent *
1075 configfs_find_subsys_dentry(struct configfs_dirent *root_sd,
1076 struct config_item *subsys_item)
1078 struct configfs_dirent *p;
1079 struct configfs_dirent *ret = NULL;
1081 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1082 if (p->s_type & CONFIGFS_DIR &&
1083 p->s_element == subsys_item) {
1093 int configfs_depend_item(struct configfs_subsystem *subsys,
1094 struct config_item *target)
1097 struct configfs_dirent *subsys_sd;
1098 struct config_item *s_item = &subsys->su_group.cg_item;
1099 struct dentry *root;
1102 * Pin the configfs filesystem. This means we can safely access
1103 * the root of the configfs filesystem.
1105 root = configfs_pin_fs();
1107 return PTR_ERR(root);
1110 * Next, lock the root directory. We're going to check that the
1111 * subsystem is really registered, and so we need to lock out
1112 * configfs_[un]register_subsystem().
1114 inode_lock(d_inode(root));
1116 subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item);
1122 /* Ok, now we can trust subsys/s_item */
1123 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1126 inode_unlock(d_inode(root));
1129 * If we succeeded, the fs is pinned via other methods. If not,
1130 * we're done with it anyway. So release_fs() is always right.
1132 configfs_release_fs();
1136 EXPORT_SYMBOL(configfs_depend_item);
1139 * Release the dependent linkage. This is much simpler than
1140 * configfs_depend_item() because we know that that the client driver is
1141 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1143 void configfs_undepend_item(struct config_item *target)
1145 struct configfs_dirent *sd;
1148 * Since we can trust everything is pinned, we just need
1149 * configfs_dirent_lock.
1151 spin_lock(&configfs_dirent_lock);
1153 sd = target->ci_dentry->d_fsdata;
1154 BUG_ON(sd->s_dependent_count < 1);
1156 sd->s_dependent_count -= 1;
1159 * After this unlock, we cannot trust the item to stay alive!
1160 * DO NOT REFERENCE item after this unlock.
1162 spin_unlock(&configfs_dirent_lock);
1164 EXPORT_SYMBOL(configfs_undepend_item);
1167 * caller_subsys is a caller's subsystem not target's. This is used to
1168 * determine if we should lock root and check subsys or not. When we are
1169 * in the same subsystem as our target there is no need to do locking as
1170 * we know that subsys is valid and is not unregistered during this function
1171 * as we are called from callback of one of his children and VFS holds a lock
1172 * on some inode. Otherwise we have to lock our root to ensure that target's
1173 * subsystem it is not unregistered during this function.
1175 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
1176 struct config_item *target)
1178 struct configfs_subsystem *target_subsys;
1179 struct config_group *root, *parent;
1180 struct configfs_dirent *subsys_sd;
1183 /* Disallow this function for configfs root */
1184 if (configfs_is_root(target))
1187 parent = target->ci_group;
1189 * This may happen when someone is trying to depend root
1190 * directory of some subsystem
1192 if (configfs_is_root(&parent->cg_item)) {
1193 target_subsys = to_configfs_subsystem(to_config_group(target));
1196 target_subsys = parent->cg_subsys;
1197 /* Find a cofnigfs root as we may need it for locking */
1198 for (root = parent; !configfs_is_root(&root->cg_item);
1199 root = root->cg_item.ci_group)
1203 if (target_subsys != caller_subsys) {
1205 * We are in other configfs subsystem, so we have to do
1206 * additional locking to prevent other subsystem from being
1209 inode_lock(d_inode(root->cg_item.ci_dentry));
1212 * As we are trying to depend item from other subsystem
1213 * we have to check if this subsystem is still registered
1215 subsys_sd = configfs_find_subsys_dentry(
1216 root->cg_item.ci_dentry->d_fsdata,
1217 &target_subsys->su_group.cg_item);
1219 goto out_root_unlock;
1221 subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata;
1224 /* Now we can execute core of depend item */
1225 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1227 if (target_subsys != caller_subsys)
1230 * We were called from subsystem other than our target so we
1231 * took some locks so now it's time to release them
1233 inode_unlock(d_inode(root->cg_item.ci_dentry));
1237 EXPORT_SYMBOL(configfs_depend_item_unlocked);
1239 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1243 struct config_group *group = NULL;
1244 struct config_item *item = NULL;
1245 struct config_item *parent_item;
1246 struct configfs_subsystem *subsys;
1247 struct configfs_dirent *sd;
1248 const struct config_item_type *type;
1249 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1252 sd = dentry->d_parent->d_fsdata;
1255 * Fake invisibility if dir belongs to a group/default groups hierarchy
1258 if (!configfs_dirent_is_ready(sd)) {
1263 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1268 /* Get a working ref for the duration of this function */
1269 parent_item = configfs_get_config_item(dentry->d_parent);
1270 type = parent_item->ci_type;
1271 subsys = to_config_group(parent_item)->cg_subsys;
1274 if (!type || !type->ct_group_ops ||
1275 (!type->ct_group_ops->make_group &&
1276 !type->ct_group_ops->make_item)) {
1277 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1282 * The subsystem may belong to a different module than the item
1283 * being created. We don't want to safely pin the new item but
1284 * fail to pin the subsystem it sits under.
1286 if (!subsys->su_group.cg_item.ci_type) {
1290 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1291 if (!try_module_get(subsys_owner)) {
1296 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1299 goto out_subsys_put;
1302 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1304 mutex_lock(&subsys->su_mutex);
1305 if (type->ct_group_ops->make_group) {
1306 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1308 group = ERR_PTR(-ENOMEM);
1309 if (!IS_ERR(group)) {
1310 link_group(to_config_group(parent_item), group);
1311 item = &group->cg_item;
1313 ret = PTR_ERR(group);
1315 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1317 item = ERR_PTR(-ENOMEM);
1319 link_obj(parent_item, item);
1321 ret = PTR_ERR(item);
1323 mutex_unlock(&subsys->su_mutex);
1328 * If ret != 0, then link_obj() was never called.
1329 * There are no extra references to clean up.
1331 goto out_subsys_put;
1335 * link_obj() has been called (via link_group() for groups).
1336 * From here on out, errors must clean that up.
1339 type = item->ci_type;
1345 new_item_owner = type->ct_owner;
1346 if (!try_module_get(new_item_owner)) {
1352 * I hate doing it this way, but if there is
1353 * an error, module_put() probably should
1354 * happen after any cleanup.
1359 * Make racing rmdir() fail if it did not tag parent with
1360 * CONFIGFS_USET_DROPPING
1361 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1362 * fail and let rmdir() terminate correctly
1364 spin_lock(&configfs_dirent_lock);
1365 /* This will make configfs_detach_prep() fail */
1366 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1367 spin_unlock(&configfs_dirent_lock);
1370 ret = configfs_attach_group(parent_item, item, dentry);
1372 ret = configfs_attach_item(parent_item, item, dentry);
1374 spin_lock(&configfs_dirent_lock);
1375 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1377 configfs_dir_set_ready(dentry->d_fsdata);
1378 spin_unlock(&configfs_dirent_lock);
1382 /* Tear down everything we built up */
1383 mutex_lock(&subsys->su_mutex);
1385 client_disconnect_notify(parent_item, item);
1387 unlink_group(group);
1390 client_drop_item(parent_item, item);
1392 mutex_unlock(&subsys->su_mutex);
1395 module_put(new_item_owner);
1400 module_put(subsys_owner);
1404 * link_obj()/link_group() took a reference from child->parent,
1405 * so the parent is safely pinned. We can drop our working
1408 config_item_put(parent_item);
1414 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1416 struct config_item *parent_item;
1417 struct config_item *item;
1418 struct configfs_subsystem *subsys;
1419 struct configfs_dirent *sd;
1420 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1423 sd = dentry->d_fsdata;
1424 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1427 /* Get a working ref until we have the child */
1428 parent_item = configfs_get_config_item(dentry->d_parent);
1429 subsys = to_config_group(parent_item)->cg_subsys;
1432 if (!parent_item->ci_type) {
1433 config_item_put(parent_item);
1437 /* configfs_mkdir() shouldn't have allowed this */
1438 BUG_ON(!subsys->su_group.cg_item.ci_type);
1439 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1442 * Ensure that no racing symlink() will make detach_prep() fail while
1443 * the new link is temporarily attached
1446 struct dentry *wait;
1448 mutex_lock(&configfs_symlink_mutex);
1449 spin_lock(&configfs_dirent_lock);
1451 * Here's where we check for dependents. We're protected by
1452 * configfs_dirent_lock.
1453 * If no dependent, atomically tag the item as dropping.
1455 ret = sd->s_dependent_count ? -EBUSY : 0;
1457 ret = configfs_detach_prep(dentry, &wait);
1459 configfs_detach_rollback(dentry);
1461 spin_unlock(&configfs_dirent_lock);
1462 mutex_unlock(&configfs_symlink_mutex);
1465 if (ret != -EAGAIN) {
1466 config_item_put(parent_item);
1470 /* Wait until the racing operation terminates */
1471 inode_lock(d_inode(wait));
1472 inode_unlock(d_inode(wait));
1475 } while (ret == -EAGAIN);
1477 /* Get a working ref for the duration of this function */
1478 item = configfs_get_config_item(dentry);
1480 /* Drop reference from above, item already holds one. */
1481 config_item_put(parent_item);
1484 dead_item_owner = item->ci_type->ct_owner;
1486 if (sd->s_type & CONFIGFS_USET_DIR) {
1487 configfs_detach_group(item);
1489 mutex_lock(&subsys->su_mutex);
1490 client_disconnect_notify(parent_item, item);
1491 unlink_group(to_config_group(item));
1493 configfs_detach_item(item);
1495 mutex_lock(&subsys->su_mutex);
1496 client_disconnect_notify(parent_item, item);
1500 client_drop_item(parent_item, item);
1501 mutex_unlock(&subsys->su_mutex);
1503 /* Drop our reference from above */
1504 config_item_put(item);
1506 module_put(dead_item_owner);
1507 module_put(subsys_owner);
1512 const struct inode_operations configfs_dir_inode_operations = {
1513 .mkdir = configfs_mkdir,
1514 .rmdir = configfs_rmdir,
1515 .symlink = configfs_symlink,
1516 .unlink = configfs_unlink,
1517 .lookup = configfs_lookup,
1518 .setattr = configfs_setattr,
1521 const struct inode_operations configfs_root_inode_operations = {
1522 .lookup = configfs_lookup,
1523 .setattr = configfs_setattr,
1527 int configfs_rename_dir(struct config_item * item, const char *new_name)
1530 struct dentry * new_dentry, * parent;
1532 if (!strcmp(config_item_name(item), new_name))
1538 down_write(&configfs_rename_sem);
1539 parent = item->parent->dentry;
1541 inode_lock(d_inode(parent));
1543 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1544 if (!IS_ERR(new_dentry)) {
1545 if (d_really_is_negative(new_dentry)) {
1546 error = config_item_set_name(item, "%s", new_name);
1548 d_add(new_dentry, NULL);
1549 d_move(item->dentry, new_dentry);
1552 d_delete(new_dentry);
1557 inode_unlock(d_inode(parent));
1558 up_write(&configfs_rename_sem);
1564 static int configfs_dir_open(struct inode *inode, struct file *file)
1566 struct dentry * dentry = file->f_path.dentry;
1567 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1570 inode_lock(d_inode(dentry));
1572 * Fake invisibility if dir belongs to a group/default groups hierarchy
1576 if (configfs_dirent_is_ready(parent_sd)) {
1577 file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
1578 if (IS_ERR(file->private_data))
1579 err = PTR_ERR(file->private_data);
1583 inode_unlock(d_inode(dentry));
1588 static int configfs_dir_close(struct inode *inode, struct file *file)
1590 struct dentry * dentry = file->f_path.dentry;
1591 struct configfs_dirent * cursor = file->private_data;
1593 inode_lock(d_inode(dentry));
1594 spin_lock(&configfs_dirent_lock);
1595 list_del_init(&cursor->s_sibling);
1596 spin_unlock(&configfs_dirent_lock);
1597 inode_unlock(d_inode(dentry));
1599 release_configfs_dirent(cursor);
1604 /* Relationship between s_mode and the DT_xxx types */
1605 static inline unsigned char dt_type(struct configfs_dirent *sd)
1607 return (sd->s_mode >> 12) & 15;
1610 static int configfs_readdir(struct file *file, struct dir_context *ctx)
1612 struct dentry *dentry = file->f_path.dentry;
1613 struct super_block *sb = dentry->d_sb;
1614 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1615 struct configfs_dirent *cursor = file->private_data;
1616 struct list_head *p, *q = &cursor->s_sibling;
1619 if (!dir_emit_dots(file, ctx))
1621 spin_lock(&configfs_dirent_lock);
1623 list_move(q, &parent_sd->s_children);
1624 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1625 struct configfs_dirent *next;
1628 struct inode *inode = NULL;
1630 next = list_entry(p, struct configfs_dirent, s_sibling);
1631 if (!next->s_element)
1635 * We'll have a dentry and an inode for
1636 * PINNED items and for open attribute
1637 * files. We lock here to prevent a race
1638 * with configfs_d_iput() clearing
1639 * s_dentry before calling iput().
1641 * Why do we go to the trouble? If
1642 * someone has an attribute file open,
1643 * the inode number should match until
1644 * they close it. Beyond that, we don't
1647 dentry = next->s_dentry;
1649 inode = d_inode(dentry);
1652 spin_unlock(&configfs_dirent_lock);
1654 ino = iunique(sb, 2);
1656 name = configfs_get_name(next);
1659 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1662 spin_lock(&configfs_dirent_lock);
1667 spin_unlock(&configfs_dirent_lock);
1671 static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1673 struct dentry * dentry = file->f_path.dentry;
1677 offset += file->f_pos;
1686 if (offset != file->f_pos) {
1687 file->f_pos = offset;
1688 if (file->f_pos >= 2) {
1689 struct configfs_dirent *sd = dentry->d_fsdata;
1690 struct configfs_dirent *cursor = file->private_data;
1691 struct list_head *p;
1692 loff_t n = file->f_pos - 2;
1694 spin_lock(&configfs_dirent_lock);
1695 list_del(&cursor->s_sibling);
1696 p = sd->s_children.next;
1697 while (n && p != &sd->s_children) {
1698 struct configfs_dirent *next;
1699 next = list_entry(p, struct configfs_dirent,
1701 if (next->s_element)
1705 list_add_tail(&cursor->s_sibling, p);
1706 spin_unlock(&configfs_dirent_lock);
1712 const struct file_operations configfs_dir_operations = {
1713 .open = configfs_dir_open,
1714 .release = configfs_dir_close,
1715 .llseek = configfs_dir_lseek,
1716 .read = generic_read_dir,
1717 .iterate_shared = configfs_readdir,
1721 * configfs_register_group - creates a parent-child relation between two groups
1722 * @parent_group: parent group
1723 * @group: child group
1725 * link groups, creates dentry for the child and attaches it to the
1728 * Return: 0 on success, negative errno code on error
1730 int configfs_register_group(struct config_group *parent_group,
1731 struct config_group *group)
1733 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1734 struct dentry *parent;
1737 mutex_lock(&subsys->su_mutex);
1738 link_group(parent_group, group);
1739 mutex_unlock(&subsys->su_mutex);
1741 parent = parent_group->cg_item.ci_dentry;
1743 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1744 ret = create_default_group(parent_group, group);
1748 spin_lock(&configfs_dirent_lock);
1749 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1750 spin_unlock(&configfs_dirent_lock);
1751 inode_unlock(d_inode(parent));
1754 inode_unlock(d_inode(parent));
1755 mutex_lock(&subsys->su_mutex);
1756 unlink_group(group);
1757 mutex_unlock(&subsys->su_mutex);
1760 EXPORT_SYMBOL(configfs_register_group);
1763 * configfs_unregister_group() - unregisters a child group from its parent
1764 * @group: parent group to be unregistered
1766 * Undoes configfs_register_group()
1768 void configfs_unregister_group(struct config_group *group)
1770 struct configfs_subsystem *subsys = group->cg_subsys;
1771 struct dentry *dentry = group->cg_item.ci_dentry;
1772 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1774 mutex_lock(&subsys->su_mutex);
1775 if (!group->cg_item.ci_parent->ci_group) {
1777 * The parent has already been unlinked and detached
1782 mutex_unlock(&subsys->su_mutex);
1784 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1785 spin_lock(&configfs_dirent_lock);
1786 configfs_detach_prep(dentry, NULL);
1787 spin_unlock(&configfs_dirent_lock);
1789 configfs_detach_group(&group->cg_item);
1790 d_inode(dentry)->i_flags |= S_DEAD;
1792 fsnotify_rmdir(d_inode(parent), dentry);
1794 inode_unlock(d_inode(parent));
1798 mutex_lock(&subsys->su_mutex);
1800 unlink_group(group);
1801 mutex_unlock(&subsys->su_mutex);
1803 EXPORT_SYMBOL(configfs_unregister_group);
1806 * configfs_register_default_group() - allocates and registers a child group
1807 * @parent_group: parent group
1808 * @name: child group name
1809 * @item_type: child item type description
1811 * boilerplate to allocate and register a child group with its parent. We need
1812 * kzalloc'ed memory because child's default_group is initially empty.
1814 * Return: allocated config group or ERR_PTR() on error
1816 struct config_group *
1817 configfs_register_default_group(struct config_group *parent_group,
1819 const struct config_item_type *item_type)
1822 struct config_group *group;
1824 group = kzalloc(sizeof(*group), GFP_KERNEL);
1826 return ERR_PTR(-ENOMEM);
1827 config_group_init_type_name(group, name, item_type);
1829 ret = configfs_register_group(parent_group, group);
1832 return ERR_PTR(ret);
1836 EXPORT_SYMBOL(configfs_register_default_group);
1839 * configfs_unregister_default_group() - unregisters and frees a child group
1840 * @group: the group to act on
1842 void configfs_unregister_default_group(struct config_group *group)
1844 configfs_unregister_group(group);
1847 EXPORT_SYMBOL(configfs_unregister_default_group);
1849 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1852 struct config_group *group = &subsys->su_group;
1853 struct dentry *dentry;
1854 struct dentry *root;
1855 struct configfs_dirent *sd;
1857 root = configfs_pin_fs();
1859 return PTR_ERR(root);
1861 if (!group->cg_item.ci_name)
1862 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1864 sd = root->d_fsdata;
1865 link_group(to_config_group(sd->s_element), group);
1867 inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
1870 dentry = d_alloc_name(root, group->cg_item.ci_name);
1872 d_add(dentry, NULL);
1874 err = configfs_attach_group(sd->s_element, &group->cg_item,
1877 BUG_ON(d_inode(dentry));
1881 spin_lock(&configfs_dirent_lock);
1882 configfs_dir_set_ready(dentry->d_fsdata);
1883 spin_unlock(&configfs_dirent_lock);
1887 inode_unlock(d_inode(root));
1890 unlink_group(group);
1891 configfs_release_fs();
1897 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1899 struct config_group *group = &subsys->su_group;
1900 struct dentry *dentry = group->cg_item.ci_dentry;
1901 struct dentry *root = dentry->d_sb->s_root;
1903 if (dentry->d_parent != root) {
1904 pr_err("Tried to unregister non-subsystem!\n");
1908 inode_lock_nested(d_inode(root),
1910 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
1911 mutex_lock(&configfs_symlink_mutex);
1912 spin_lock(&configfs_dirent_lock);
1913 if (configfs_detach_prep(dentry, NULL)) {
1914 pr_err("Tried to unregister non-empty subsystem!\n");
1916 spin_unlock(&configfs_dirent_lock);
1917 mutex_unlock(&configfs_symlink_mutex);
1918 configfs_detach_group(&group->cg_item);
1919 d_inode(dentry)->i_flags |= S_DEAD;
1921 fsnotify_rmdir(d_inode(root), dentry);
1922 inode_unlock(d_inode(dentry));
1926 inode_unlock(d_inode(root));
1930 unlink_group(group);
1931 configfs_release_fs();
1934 EXPORT_SYMBOL(configfs_register_subsystem);
1935 EXPORT_SYMBOL(configfs_unregister_subsystem);