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"
26 * Protects mutations of configfs_dirent linkage together with proper i_mutex
27 * Also protects mutations of symlinks linkage to target configfs_dirent
28 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
29 * and configfs_dirent_lock locked, in that order.
30 * This allows one to safely traverse configfs_dirent trees and symlinks without
31 * having to lock inodes.
33 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
34 * unlocked is not reliable unless in detach_groups() called from
35 * rmdir()/unregister() and from configfs_attach_group()
37 DEFINE_SPINLOCK(configfs_dirent_lock);
39 static void configfs_d_iput(struct dentry * dentry,
42 struct configfs_dirent *sd = dentry->d_fsdata;
45 /* Coordinate with configfs_readdir */
46 spin_lock(&configfs_dirent_lock);
48 * Set sd->s_dentry to null only when this dentry is the one
49 * that is going to be killed. Otherwise configfs_d_iput may
50 * run just after configfs_attach_attr and set sd->s_dentry to
51 * NULL even it's still in use.
53 if (sd->s_dentry == dentry)
56 spin_unlock(&configfs_dirent_lock);
62 const struct dentry_operations configfs_dentry_ops = {
63 .d_iput = configfs_d_iput,
64 .d_delete = always_delete_dentry,
70 * Helpers to make lockdep happy with our recursive locking of default groups'
71 * inodes (see configfs_attach_group() and configfs_detach_group()).
72 * We put default groups i_mutexes in separate classes according to their depth
73 * from the youngest non-default group ancestor.
75 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
76 * groups A/B and A/C will have their inode's mutex in class
77 * default_group_class[0], and default group A/C/D will be in
78 * default_group_class[1].
80 * The lock classes are declared and assigned in inode.c, according to the
82 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
83 * default groups, and reset to -1 when all default groups are attached. During
84 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
85 * inode's mutex is set to default_group_class[s_depth - 1].
88 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
93 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
94 struct configfs_dirent *sd)
96 int parent_depth = parent_sd->s_depth;
98 if (parent_depth >= 0)
99 sd->s_depth = parent_depth + 1;
103 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
106 * item's i_mutex class is already setup, so s_depth is now only
107 * used to set new sub-directories s_depth, which is always done
108 * with item's i_mutex locked.
111 * sd->s_depth == -1 iff we are a non default group.
112 * else (we are a default group) sd->s_depth > 0 (see
115 if (sd->s_depth == -1)
117 * We are a non default group and we are going to create
124 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
126 /* We will not create default groups anymore. */
130 #else /* CONFIG_LOCKDEP */
132 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
136 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
137 struct configfs_dirent *sd)
142 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
147 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
151 #endif /* CONFIG_LOCKDEP */
153 static struct configfs_fragment *new_fragment(void)
155 struct configfs_fragment *p;
157 p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL);
159 atomic_set(&p->frag_count, 1);
160 init_rwsem(&p->frag_sem);
161 p->frag_dead = false;
166 void put_fragment(struct configfs_fragment *frag)
168 if (frag && atomic_dec_and_test(&frag->frag_count))
172 struct configfs_fragment *get_fragment(struct configfs_fragment *frag)
175 atomic_inc(&frag->frag_count);
180 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
182 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
183 void *element, int type,
184 struct configfs_fragment *frag)
186 struct configfs_dirent * sd;
188 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
190 return ERR_PTR(-ENOMEM);
192 atomic_set(&sd->s_count, 1);
193 INIT_LIST_HEAD(&sd->s_children);
194 sd->s_element = element;
196 configfs_init_dirent_depth(sd);
197 spin_lock(&configfs_dirent_lock);
198 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
199 spin_unlock(&configfs_dirent_lock);
200 kmem_cache_free(configfs_dir_cachep, sd);
201 return ERR_PTR(-ENOENT);
203 sd->s_frag = get_fragment(frag);
204 list_add(&sd->s_sibling, &parent_sd->s_children);
205 spin_unlock(&configfs_dirent_lock);
212 * Return -EEXIST if there is already a configfs element with the same
213 * name for the same parent.
215 * called with parent inode's i_mutex held
217 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
218 const unsigned char *new)
220 struct configfs_dirent * sd;
222 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
224 const unsigned char *existing = configfs_get_name(sd);
225 if (strcmp(existing, new))
236 int configfs_make_dirent(struct configfs_dirent * parent_sd,
237 struct dentry * dentry, void * element,
238 umode_t mode, int type, struct configfs_fragment *frag)
240 struct configfs_dirent * sd;
242 sd = configfs_new_dirent(parent_sd, element, type, frag);
247 sd->s_dentry = dentry;
249 dentry->d_fsdata = configfs_get(sd);
254 static void configfs_remove_dirent(struct dentry *dentry)
256 struct configfs_dirent *sd = dentry->d_fsdata;
260 spin_lock(&configfs_dirent_lock);
261 list_del_init(&sd->s_sibling);
262 spin_unlock(&configfs_dirent_lock);
267 * configfs_create_dir - create a directory for an config_item.
268 * @item: config_itemwe're creating directory for.
269 * @dentry: config_item's dentry.
270 * @frag: config_item's fragment.
272 * Note: user-created entries won't be allowed under this new directory
273 * until it is validated by configfs_dir_set_ready()
276 static int configfs_create_dir(struct config_item *item, struct dentry *dentry,
277 struct configfs_fragment *frag)
280 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
281 struct dentry *p = dentry->d_parent;
286 error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
290 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
291 CONFIGFS_DIR | CONFIGFS_USET_CREATING,
296 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
297 inode = configfs_create(dentry, mode);
301 inode->i_op = &configfs_dir_inode_operations;
302 inode->i_fop = &configfs_dir_operations;
303 /* directory inodes start off with i_nlink == 2 (for "." entry) */
305 d_instantiate(dentry, inode);
307 dget(dentry); /* pin directory dentries in core */
308 inc_nlink(d_inode(p));
309 item->ci_dentry = dentry;
313 configfs_remove_dirent(dentry);
314 return PTR_ERR(inode);
318 * Allow userspace to create new entries under a new directory created with
319 * configfs_create_dir(), and under all of its chidlren directories recursively.
320 * @sd configfs_dirent of the new directory to validate
322 * Caller must hold configfs_dirent_lock.
324 static void configfs_dir_set_ready(struct configfs_dirent *sd)
326 struct configfs_dirent *child_sd;
328 sd->s_type &= ~CONFIGFS_USET_CREATING;
329 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
330 if (child_sd->s_type & CONFIGFS_USET_CREATING)
331 configfs_dir_set_ready(child_sd);
335 * Check that a directory does not belong to a directory hierarchy being
336 * attached and not validated yet.
337 * @sd configfs_dirent of the directory to check
339 * @return non-zero iff the directory was validated
341 * Note: takes configfs_dirent_lock, so the result may change from false to true
342 * in two consecutive calls, but never from true to false.
344 int configfs_dirent_is_ready(struct configfs_dirent *sd)
348 spin_lock(&configfs_dirent_lock);
349 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
350 spin_unlock(&configfs_dirent_lock);
355 int configfs_create_link(struct configfs_dirent *target, struct dentry *parent,
356 struct dentry *dentry, char *body)
359 umode_t mode = S_IFLNK | S_IRWXUGO;
360 struct configfs_dirent *p = parent->d_fsdata;
363 err = configfs_make_dirent(p, dentry, target, mode, CONFIGFS_ITEM_LINK,
368 inode = configfs_create(dentry, mode);
372 inode->i_link = body;
373 inode->i_op = &configfs_symlink_inode_operations;
374 d_instantiate(dentry, inode);
375 dget(dentry); /* pin link dentries in core */
379 configfs_remove_dirent(dentry);
380 return PTR_ERR(inode);
383 static void remove_dir(struct dentry * d)
385 struct dentry * parent = dget(d->d_parent);
387 configfs_remove_dirent(d);
389 if (d_really_is_positive(d))
390 simple_rmdir(d_inode(parent),d);
392 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
398 * configfs_remove_dir - remove an config_item's directory.
399 * @item: config_item we're removing.
401 * The only thing special about this is that we remove any files in
402 * the directory before we remove the directory, and we've inlined
403 * what used to be configfs_rmdir() below, instead of calling separately.
405 * Caller holds the mutex of the item's inode
408 static void configfs_remove_dir(struct config_item * item)
410 struct dentry * dentry = dget(item->ci_dentry);
417 * Drop reference from dget() on entrance.
423 /* attaches attribute's configfs_dirent to the dentry corresponding to the
426 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
428 struct configfs_attribute * attr = sd->s_element;
431 spin_lock(&configfs_dirent_lock);
432 dentry->d_fsdata = configfs_get(sd);
433 sd->s_dentry = dentry;
434 spin_unlock(&configfs_dirent_lock);
436 inode = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG);
439 return PTR_ERR(inode);
441 if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) {
443 inode->i_fop = &configfs_bin_file_operations;
445 inode->i_size = PAGE_SIZE;
446 inode->i_fop = &configfs_file_operations;
448 d_add(dentry, inode);
452 static struct dentry * configfs_lookup(struct inode *dir,
453 struct dentry *dentry,
456 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
457 struct configfs_dirent * sd;
462 * Fake invisibility if dir belongs to a group/default groups hierarchy
465 * This forbids userspace to read/write attributes of items which may
466 * not complete their initialization, since the dentries of the
467 * attributes won't be instantiated.
470 if (!configfs_dirent_is_ready(parent_sd))
473 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
474 if (sd->s_type & CONFIGFS_NOT_PINNED) {
475 const unsigned char * name = configfs_get_name(sd);
477 if (strcmp(name, dentry->d_name.name))
481 err = configfs_attach_attr(sd, dentry);
488 * If it doesn't exist and it isn't a NOT_PINNED item,
489 * it must be negative.
491 if (dentry->d_name.len > NAME_MAX)
492 return ERR_PTR(-ENAMETOOLONG);
502 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
503 * attributes and are removed by rmdir(). We recurse, setting
504 * CONFIGFS_USET_DROPPING on all children that are candidates for
506 * If there is an error, the caller will reset the flags via
507 * configfs_detach_rollback().
509 static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait)
511 struct configfs_dirent *parent_sd = dentry->d_fsdata;
512 struct configfs_dirent *sd;
515 /* Mark that we're trying to drop the group */
516 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
519 if (parent_sd->s_links)
523 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
524 if (!sd->s_element ||
525 (sd->s_type & CONFIGFS_NOT_PINNED))
527 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
528 /* Abort if racing with mkdir() */
529 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
531 *wait= dget(sd->s_dentry);
536 * Yup, recursive. If there's a problem, blame
537 * deep nesting of default_groups
539 ret = configfs_detach_prep(sd->s_dentry, wait);
553 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
556 static void configfs_detach_rollback(struct dentry *dentry)
558 struct configfs_dirent *parent_sd = dentry->d_fsdata;
559 struct configfs_dirent *sd;
561 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
563 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
564 if (sd->s_type & CONFIGFS_USET_DEFAULT)
565 configfs_detach_rollback(sd->s_dentry);
568 static void detach_attrs(struct config_item * item)
570 struct dentry * dentry = dget(item->ci_dentry);
571 struct configfs_dirent * parent_sd;
572 struct configfs_dirent * sd, * tmp;
577 pr_debug("configfs %s: dropping attrs for dir\n",
578 dentry->d_name.name);
580 parent_sd = dentry->d_fsdata;
581 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
582 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
584 spin_lock(&configfs_dirent_lock);
585 list_del_init(&sd->s_sibling);
586 spin_unlock(&configfs_dirent_lock);
587 configfs_drop_dentry(sd, dentry);
592 * Drop reference from dget() on entrance.
597 static int populate_attrs(struct config_item *item)
599 const struct config_item_type *t = item->ci_type;
600 struct configfs_attribute *attr;
601 struct configfs_bin_attribute *bin_attr;
608 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
609 if ((error = configfs_create_file(item, attr)))
613 if (t->ct_bin_attrs) {
614 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
615 error = configfs_create_bin_file(item, bin_attr);
627 static int configfs_attach_group(struct config_item *parent_item,
628 struct config_item *item,
629 struct dentry *dentry,
630 struct configfs_fragment *frag);
631 static void configfs_detach_group(struct config_item *item);
633 static void detach_groups(struct config_group *group)
635 struct dentry * dentry = dget(group->cg_item.ci_dentry);
636 struct dentry *child;
637 struct configfs_dirent *parent_sd;
638 struct configfs_dirent *sd, *tmp;
643 parent_sd = dentry->d_fsdata;
644 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
645 if (!sd->s_element ||
646 !(sd->s_type & CONFIGFS_USET_DEFAULT))
649 child = sd->s_dentry;
651 inode_lock(d_inode(child));
653 configfs_detach_group(sd->s_element);
654 d_inode(child)->i_flags |= S_DEAD;
657 inode_unlock(d_inode(child));
664 * Drop reference from dget() on entrance.
670 * This fakes mkdir(2) on a default_groups[] entry. It
671 * creates a dentry, attachs it, and then does fixup
674 * We could, perhaps, tweak our parent's ->mkdir for a minute and
675 * try using vfs_mkdir. Just a thought.
677 static int create_default_group(struct config_group *parent_group,
678 struct config_group *group,
679 struct configfs_fragment *frag)
682 struct configfs_dirent *sd;
683 /* We trust the caller holds a reference to parent */
684 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
686 if (!group->cg_item.ci_name)
687 group->cg_item.ci_name = group->cg_item.ci_namebuf;
690 child = d_alloc_name(parent, group->cg_item.ci_name);
694 ret = configfs_attach_group(&parent_group->cg_item,
695 &group->cg_item, child, frag);
697 sd = child->d_fsdata;
698 sd->s_type |= CONFIGFS_USET_DEFAULT;
700 BUG_ON(d_inode(child));
709 static int populate_groups(struct config_group *group,
710 struct configfs_fragment *frag)
712 struct config_group *new_group;
715 list_for_each_entry(new_group, &group->default_groups, group_entry) {
716 ret = create_default_group(group, new_group, frag);
718 detach_groups(group);
726 void configfs_remove_default_groups(struct config_group *group)
728 struct config_group *g, *n;
730 list_for_each_entry_safe(g, n, &group->default_groups, group_entry) {
731 list_del(&g->group_entry);
732 config_item_put(&g->cg_item);
735 EXPORT_SYMBOL(configfs_remove_default_groups);
738 * All of link_obj/unlink_obj/link_group/unlink_group require that
739 * subsys->su_mutex is held.
742 static void unlink_obj(struct config_item *item)
744 struct config_group *group;
746 group = item->ci_group;
748 list_del_init(&item->ci_entry);
750 item->ci_group = NULL;
751 item->ci_parent = NULL;
753 /* Drop the reference for ci_entry */
754 config_item_put(item);
756 /* Drop the reference for ci_parent */
757 config_group_put(group);
761 static void link_obj(struct config_item *parent_item, struct config_item *item)
764 * Parent seems redundant with group, but it makes certain
765 * traversals much nicer.
767 item->ci_parent = parent_item;
770 * We hold a reference on the parent for the child's ci_parent
773 item->ci_group = config_group_get(to_config_group(parent_item));
774 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
777 * We hold a reference on the child for ci_entry on the parent's
780 config_item_get(item);
783 static void unlink_group(struct config_group *group)
785 struct config_group *new_group;
787 list_for_each_entry(new_group, &group->default_groups, group_entry)
788 unlink_group(new_group);
790 group->cg_subsys = NULL;
791 unlink_obj(&group->cg_item);
794 static void link_group(struct config_group *parent_group, struct config_group *group)
796 struct config_group *new_group;
797 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
799 link_obj(&parent_group->cg_item, &group->cg_item);
801 if (parent_group->cg_subsys)
802 subsys = parent_group->cg_subsys;
803 else if (configfs_is_root(&parent_group->cg_item))
804 subsys = to_configfs_subsystem(group);
807 group->cg_subsys = subsys;
809 list_for_each_entry(new_group, &group->default_groups, group_entry)
810 link_group(group, new_group);
814 * The goal is that configfs_attach_item() (and
815 * configfs_attach_group()) can be called from either the VFS or this
816 * module. That is, they assume that the items have been created,
817 * the dentry allocated, and the dcache is all ready to go.
819 * If they fail, they must clean up after themselves as if they
820 * had never been called. The caller (VFS or local function) will
821 * handle cleaning up the dcache bits.
823 * configfs_detach_group() and configfs_detach_item() behave similarly on
824 * the way out. They assume that the proper semaphores are held, they
825 * clean up the configfs items, and they expect their callers will
826 * handle the dcache bits.
828 static int configfs_attach_item(struct config_item *parent_item,
829 struct config_item *item,
830 struct dentry *dentry,
831 struct configfs_fragment *frag)
835 ret = configfs_create_dir(item, dentry, frag);
837 ret = populate_attrs(item);
840 * We are going to remove an inode and its dentry but
841 * the VFS may already have hit and used them. Thus,
842 * we must lock them as rmdir() would.
844 inode_lock(d_inode(dentry));
845 configfs_remove_dir(item);
846 d_inode(dentry)->i_flags |= S_DEAD;
848 inode_unlock(d_inode(dentry));
856 /* Caller holds the mutex of the item's inode */
857 static void configfs_detach_item(struct config_item *item)
860 configfs_remove_dir(item);
863 static int configfs_attach_group(struct config_item *parent_item,
864 struct config_item *item,
865 struct dentry *dentry,
866 struct configfs_fragment *frag)
869 struct configfs_dirent *sd;
871 ret = configfs_attach_item(parent_item, item, dentry, frag);
873 sd = dentry->d_fsdata;
874 sd->s_type |= CONFIGFS_USET_DIR;
877 * FYI, we're faking mkdir in populate_groups()
878 * We must lock the group's inode to avoid races with the VFS
879 * which can already hit the inode and try to add/remove entries
882 * We must also lock the inode to remove it safely in case of
883 * error, as rmdir() would.
885 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
886 configfs_adjust_dir_dirent_depth_before_populate(sd);
887 ret = populate_groups(to_config_group(item), frag);
889 configfs_detach_item(item);
890 d_inode(dentry)->i_flags |= S_DEAD;
893 configfs_adjust_dir_dirent_depth_after_populate(sd);
894 inode_unlock(d_inode(dentry));
902 /* Caller holds the mutex of the group's inode */
903 static void configfs_detach_group(struct config_item *item)
905 detach_groups(to_config_group(item));
906 configfs_detach_item(item);
910 * After the item has been detached from the filesystem view, we are
911 * ready to tear it out of the hierarchy. Notify the client before
912 * we do that so they can perform any cleanup that requires
913 * navigating the hierarchy. A client does not need to provide this
914 * callback. The subsystem semaphore MUST be held by the caller, and
915 * references must be valid for both items. It also assumes the
916 * caller has validated ci_type.
918 static void client_disconnect_notify(struct config_item *parent_item,
919 struct config_item *item)
921 const struct config_item_type *type;
923 type = parent_item->ci_type;
926 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
927 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
932 * Drop the initial reference from make_item()/make_group()
933 * This function assumes that reference is held on item
934 * and that item holds a valid reference to the parent. Also, it
935 * assumes the caller has validated ci_type.
937 static void client_drop_item(struct config_item *parent_item,
938 struct config_item *item)
940 const struct config_item_type *type;
942 type = parent_item->ci_type;
946 * If ->drop_item() exists, it is responsible for the
949 if (type->ct_group_ops && type->ct_group_ops->drop_item)
950 type->ct_group_ops->drop_item(to_config_group(parent_item),
953 config_item_put(item);
957 static void configfs_dump_one(struct configfs_dirent *sd, int level)
959 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
961 #define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type);
962 type_print(CONFIGFS_ROOT);
963 type_print(CONFIGFS_DIR);
964 type_print(CONFIGFS_ITEM_ATTR);
965 type_print(CONFIGFS_ITEM_LINK);
966 type_print(CONFIGFS_USET_DIR);
967 type_print(CONFIGFS_USET_DEFAULT);
968 type_print(CONFIGFS_USET_DROPPING);
972 static int configfs_dump(struct configfs_dirent *sd, int level)
974 struct configfs_dirent *child_sd;
977 configfs_dump_one(sd, level);
979 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
982 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
983 ret = configfs_dump(child_sd, level + 2);
994 * configfs_depend_item() and configfs_undepend_item()
996 * WARNING: Do not call these from a configfs callback!
998 * This describes these functions and their helpers.
1000 * Allow another kernel system to depend on a config_item. If this
1001 * happens, the item cannot go away until the dependent can live without
1002 * it. The idea is to give client modules as simple an interface as
1003 * possible. When a system asks them to depend on an item, they just
1004 * call configfs_depend_item(). If the item is live and the client
1005 * driver is in good shape, we'll happily do the work for them.
1007 * Why is the locking complex? Because configfs uses the VFS to handle
1008 * all locking, but this function is called outside the normal
1009 * VFS->configfs path. So it must take VFS locks to prevent the
1010 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1011 * why you can't call these functions underneath configfs callbacks.
1013 * Note, btw, that this can be called at *any* time, even when a configfs
1014 * subsystem isn't registered, or when configfs is loading or unloading.
1015 * Just like configfs_register_subsystem(). So we take the same
1016 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1017 * If we can find the target item in the
1018 * configfs tree, it must be part of the subsystem tree as well, so we
1019 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1020 * locking out mkdir() and rmdir(), who might be racing us.
1024 * configfs_depend_prep()
1026 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1027 * attributes. This is similar but not the same to configfs_detach_prep().
1028 * Note that configfs_detach_prep() expects the parent to be locked when it
1029 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1030 * do that so we can unlock it if we find nothing.
1032 * Here we do a depth-first search of the dentry hierarchy looking for
1034 * We deliberately ignore items tagged as dropping since they are virtually
1035 * dead, as well as items in the middle of attachment since they virtually
1036 * do not exist yet. This completes the locking out of racing mkdir() and
1038 * Note: subdirectories in the middle of attachment start with s_type =
1039 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1040 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1041 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1043 * If the target is not found, -ENOENT is bubbled up.
1045 * This adds a requirement that all config_items be unique!
1047 * This is recursive. There isn't
1048 * much on the stack, though, so folks that need this function - be careful
1049 * about your stack! Patches will be accepted to make it iterative.
1051 static int configfs_depend_prep(struct dentry *origin,
1052 struct config_item *target)
1054 struct configfs_dirent *child_sd, *sd;
1057 BUG_ON(!origin || !origin->d_fsdata);
1058 sd = origin->d_fsdata;
1060 if (sd->s_element == target) /* Boo-yah */
1063 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1064 if ((child_sd->s_type & CONFIGFS_DIR) &&
1065 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1066 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1067 ret = configfs_depend_prep(child_sd->s_dentry,
1070 goto out; /* Child path boo-yah */
1074 /* We looped all our children and didn't find target */
1081 static int configfs_do_depend_item(struct dentry *subsys_dentry,
1082 struct config_item *target)
1084 struct configfs_dirent *p;
1087 spin_lock(&configfs_dirent_lock);
1088 /* Scan the tree, return 0 if found */
1089 ret = configfs_depend_prep(subsys_dentry, target);
1091 goto out_unlock_dirent_lock;
1094 * We are sure that the item is not about to be removed by rmdir(), and
1095 * not in the middle of attachment by mkdir().
1097 p = target->ci_dentry->d_fsdata;
1098 p->s_dependent_count += 1;
1100 out_unlock_dirent_lock:
1101 spin_unlock(&configfs_dirent_lock);
1106 static inline struct configfs_dirent *
1107 configfs_find_subsys_dentry(struct configfs_dirent *root_sd,
1108 struct config_item *subsys_item)
1110 struct configfs_dirent *p;
1111 struct configfs_dirent *ret = NULL;
1113 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1114 if (p->s_type & CONFIGFS_DIR &&
1115 p->s_element == subsys_item) {
1125 int configfs_depend_item(struct configfs_subsystem *subsys,
1126 struct config_item *target)
1129 struct configfs_dirent *subsys_sd;
1130 struct config_item *s_item = &subsys->su_group.cg_item;
1131 struct dentry *root;
1134 * Pin the configfs filesystem. This means we can safely access
1135 * the root of the configfs filesystem.
1137 root = configfs_pin_fs();
1139 return PTR_ERR(root);
1142 * Next, lock the root directory. We're going to check that the
1143 * subsystem is really registered, and so we need to lock out
1144 * configfs_[un]register_subsystem().
1146 inode_lock(d_inode(root));
1148 subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item);
1154 /* Ok, now we can trust subsys/s_item */
1155 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1158 inode_unlock(d_inode(root));
1161 * If we succeeded, the fs is pinned via other methods. If not,
1162 * we're done with it anyway. So release_fs() is always right.
1164 configfs_release_fs();
1168 EXPORT_SYMBOL(configfs_depend_item);
1171 * Release the dependent linkage. This is much simpler than
1172 * configfs_depend_item() because we know that the client driver is
1173 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1175 void configfs_undepend_item(struct config_item *target)
1177 struct configfs_dirent *sd;
1180 * Since we can trust everything is pinned, we just need
1181 * configfs_dirent_lock.
1183 spin_lock(&configfs_dirent_lock);
1185 sd = target->ci_dentry->d_fsdata;
1186 BUG_ON(sd->s_dependent_count < 1);
1188 sd->s_dependent_count -= 1;
1191 * After this unlock, we cannot trust the item to stay alive!
1192 * DO NOT REFERENCE item after this unlock.
1194 spin_unlock(&configfs_dirent_lock);
1196 EXPORT_SYMBOL(configfs_undepend_item);
1199 * caller_subsys is a caller's subsystem not target's. This is used to
1200 * determine if we should lock root and check subsys or not. When we are
1201 * in the same subsystem as our target there is no need to do locking as
1202 * we know that subsys is valid and is not unregistered during this function
1203 * as we are called from callback of one of his children and VFS holds a lock
1204 * on some inode. Otherwise we have to lock our root to ensure that target's
1205 * subsystem it is not unregistered during this function.
1207 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
1208 struct config_item *target)
1210 struct configfs_subsystem *target_subsys;
1211 struct config_group *root, *parent;
1212 struct configfs_dirent *subsys_sd;
1215 /* Disallow this function for configfs root */
1216 if (configfs_is_root(target))
1219 parent = target->ci_group;
1221 * This may happen when someone is trying to depend root
1222 * directory of some subsystem
1224 if (configfs_is_root(&parent->cg_item)) {
1225 target_subsys = to_configfs_subsystem(to_config_group(target));
1228 target_subsys = parent->cg_subsys;
1229 /* Find a cofnigfs root as we may need it for locking */
1230 for (root = parent; !configfs_is_root(&root->cg_item);
1231 root = root->cg_item.ci_group)
1235 if (target_subsys != caller_subsys) {
1237 * We are in other configfs subsystem, so we have to do
1238 * additional locking to prevent other subsystem from being
1241 inode_lock(d_inode(root->cg_item.ci_dentry));
1244 * As we are trying to depend item from other subsystem
1245 * we have to check if this subsystem is still registered
1247 subsys_sd = configfs_find_subsys_dentry(
1248 root->cg_item.ci_dentry->d_fsdata,
1249 &target_subsys->su_group.cg_item);
1251 goto out_root_unlock;
1253 subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata;
1256 /* Now we can execute core of depend item */
1257 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1259 if (target_subsys != caller_subsys)
1262 * We were called from subsystem other than our target so we
1263 * took some locks so now it's time to release them
1265 inode_unlock(d_inode(root->cg_item.ci_dentry));
1269 EXPORT_SYMBOL(configfs_depend_item_unlocked);
1271 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1275 struct config_group *group = NULL;
1276 struct config_item *item = NULL;
1277 struct config_item *parent_item;
1278 struct configfs_subsystem *subsys;
1279 struct configfs_dirent *sd;
1280 const struct config_item_type *type;
1281 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1282 struct configfs_fragment *frag;
1285 sd = dentry->d_parent->d_fsdata;
1288 * Fake invisibility if dir belongs to a group/default groups hierarchy
1291 if (!configfs_dirent_is_ready(sd)) {
1296 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1301 frag = new_fragment();
1307 /* Get a working ref for the duration of this function */
1308 parent_item = configfs_get_config_item(dentry->d_parent);
1309 type = parent_item->ci_type;
1310 subsys = to_config_group(parent_item)->cg_subsys;
1313 if (!type || !type->ct_group_ops ||
1314 (!type->ct_group_ops->make_group &&
1315 !type->ct_group_ops->make_item)) {
1316 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1321 * The subsystem may belong to a different module than the item
1322 * being created. We don't want to safely pin the new item but
1323 * fail to pin the subsystem it sits under.
1325 if (!subsys->su_group.cg_item.ci_type) {
1329 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1330 if (!try_module_get(subsys_owner)) {
1335 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1338 goto out_subsys_put;
1341 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1343 mutex_lock(&subsys->su_mutex);
1344 if (type->ct_group_ops->make_group) {
1345 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1347 group = ERR_PTR(-ENOMEM);
1348 if (!IS_ERR(group)) {
1349 link_group(to_config_group(parent_item), group);
1350 item = &group->cg_item;
1352 ret = PTR_ERR(group);
1354 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1356 item = ERR_PTR(-ENOMEM);
1358 link_obj(parent_item, item);
1360 ret = PTR_ERR(item);
1362 mutex_unlock(&subsys->su_mutex);
1367 * If ret != 0, then link_obj() was never called.
1368 * There are no extra references to clean up.
1370 goto out_subsys_put;
1374 * link_obj() has been called (via link_group() for groups).
1375 * From here on out, errors must clean that up.
1378 type = item->ci_type;
1384 new_item_owner = type->ct_owner;
1385 if (!try_module_get(new_item_owner)) {
1391 * I hate doing it this way, but if there is
1392 * an error, module_put() probably should
1393 * happen after any cleanup.
1398 * Make racing rmdir() fail if it did not tag parent with
1399 * CONFIGFS_USET_DROPPING
1400 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1401 * fail and let rmdir() terminate correctly
1403 spin_lock(&configfs_dirent_lock);
1404 /* This will make configfs_detach_prep() fail */
1405 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1406 spin_unlock(&configfs_dirent_lock);
1409 ret = configfs_attach_group(parent_item, item, dentry, frag);
1411 ret = configfs_attach_item(parent_item, item, dentry, frag);
1413 spin_lock(&configfs_dirent_lock);
1414 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1416 configfs_dir_set_ready(dentry->d_fsdata);
1417 spin_unlock(&configfs_dirent_lock);
1421 /* Tear down everything we built up */
1422 mutex_lock(&subsys->su_mutex);
1424 client_disconnect_notify(parent_item, item);
1426 unlink_group(group);
1429 client_drop_item(parent_item, item);
1431 mutex_unlock(&subsys->su_mutex);
1434 module_put(new_item_owner);
1439 module_put(subsys_owner);
1443 * link_obj()/link_group() took a reference from child->parent,
1444 * so the parent is safely pinned. We can drop our working
1447 config_item_put(parent_item);
1454 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1456 struct config_item *parent_item;
1457 struct config_item *item;
1458 struct configfs_subsystem *subsys;
1459 struct configfs_dirent *sd;
1460 struct configfs_fragment *frag;
1461 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1464 sd = dentry->d_fsdata;
1465 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1468 /* Get a working ref until we have the child */
1469 parent_item = configfs_get_config_item(dentry->d_parent);
1470 subsys = to_config_group(parent_item)->cg_subsys;
1473 if (!parent_item->ci_type) {
1474 config_item_put(parent_item);
1478 /* configfs_mkdir() shouldn't have allowed this */
1479 BUG_ON(!subsys->su_group.cg_item.ci_type);
1480 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1483 * Ensure that no racing symlink() will make detach_prep() fail while
1484 * the new link is temporarily attached
1487 struct dentry *wait;
1489 mutex_lock(&configfs_symlink_mutex);
1490 spin_lock(&configfs_dirent_lock);
1492 * Here's where we check for dependents. We're protected by
1493 * configfs_dirent_lock.
1494 * If no dependent, atomically tag the item as dropping.
1496 ret = sd->s_dependent_count ? -EBUSY : 0;
1498 ret = configfs_detach_prep(dentry, &wait);
1500 configfs_detach_rollback(dentry);
1502 spin_unlock(&configfs_dirent_lock);
1503 mutex_unlock(&configfs_symlink_mutex);
1506 if (ret != -EAGAIN) {
1507 config_item_put(parent_item);
1511 /* Wait until the racing operation terminates */
1512 inode_lock(d_inode(wait));
1513 inode_unlock(d_inode(wait));
1516 } while (ret == -EAGAIN);
1519 if (down_write_killable(&frag->frag_sem)) {
1520 spin_lock(&configfs_dirent_lock);
1521 configfs_detach_rollback(dentry);
1522 spin_unlock(&configfs_dirent_lock);
1523 config_item_put(parent_item);
1526 frag->frag_dead = true;
1527 up_write(&frag->frag_sem);
1529 /* Get a working ref for the duration of this function */
1530 item = configfs_get_config_item(dentry);
1532 /* Drop reference from above, item already holds one. */
1533 config_item_put(parent_item);
1536 dead_item_owner = item->ci_type->ct_owner;
1538 if (sd->s_type & CONFIGFS_USET_DIR) {
1539 configfs_detach_group(item);
1541 mutex_lock(&subsys->su_mutex);
1542 client_disconnect_notify(parent_item, item);
1543 unlink_group(to_config_group(item));
1545 configfs_detach_item(item);
1547 mutex_lock(&subsys->su_mutex);
1548 client_disconnect_notify(parent_item, item);
1552 client_drop_item(parent_item, item);
1553 mutex_unlock(&subsys->su_mutex);
1555 /* Drop our reference from above */
1556 config_item_put(item);
1558 module_put(dead_item_owner);
1559 module_put(subsys_owner);
1564 const struct inode_operations configfs_dir_inode_operations = {
1565 .mkdir = configfs_mkdir,
1566 .rmdir = configfs_rmdir,
1567 .symlink = configfs_symlink,
1568 .unlink = configfs_unlink,
1569 .lookup = configfs_lookup,
1570 .setattr = configfs_setattr,
1573 const struct inode_operations configfs_root_inode_operations = {
1574 .lookup = configfs_lookup,
1575 .setattr = configfs_setattr,
1578 static int configfs_dir_open(struct inode *inode, struct file *file)
1580 struct dentry * dentry = file->f_path.dentry;
1581 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1584 inode_lock(d_inode(dentry));
1586 * Fake invisibility if dir belongs to a group/default groups hierarchy
1590 if (configfs_dirent_is_ready(parent_sd)) {
1591 file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);
1592 if (IS_ERR(file->private_data))
1593 err = PTR_ERR(file->private_data);
1597 inode_unlock(d_inode(dentry));
1602 static int configfs_dir_close(struct inode *inode, struct file *file)
1604 struct dentry * dentry = file->f_path.dentry;
1605 struct configfs_dirent * cursor = file->private_data;
1607 inode_lock(d_inode(dentry));
1608 spin_lock(&configfs_dirent_lock);
1609 list_del_init(&cursor->s_sibling);
1610 spin_unlock(&configfs_dirent_lock);
1611 inode_unlock(d_inode(dentry));
1613 release_configfs_dirent(cursor);
1618 /* Relationship between s_mode and the DT_xxx types */
1619 static inline unsigned char dt_type(struct configfs_dirent *sd)
1621 return (sd->s_mode >> 12) & 15;
1624 static int configfs_readdir(struct file *file, struct dir_context *ctx)
1626 struct dentry *dentry = file->f_path.dentry;
1627 struct super_block *sb = dentry->d_sb;
1628 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1629 struct configfs_dirent *cursor = file->private_data;
1630 struct list_head *p, *q = &cursor->s_sibling;
1633 if (!dir_emit_dots(file, ctx))
1635 spin_lock(&configfs_dirent_lock);
1637 list_move(q, &parent_sd->s_children);
1638 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1639 struct configfs_dirent *next;
1642 struct inode *inode = NULL;
1644 next = list_entry(p, struct configfs_dirent, s_sibling);
1645 if (!next->s_element)
1649 * We'll have a dentry and an inode for
1650 * PINNED items and for open attribute
1651 * files. We lock here to prevent a race
1652 * with configfs_d_iput() clearing
1653 * s_dentry before calling iput().
1655 * Why do we go to the trouble? If
1656 * someone has an attribute file open,
1657 * the inode number should match until
1658 * they close it. Beyond that, we don't
1661 dentry = next->s_dentry;
1663 inode = d_inode(dentry);
1666 spin_unlock(&configfs_dirent_lock);
1668 ino = iunique(sb, 2);
1670 name = configfs_get_name(next);
1673 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1676 spin_lock(&configfs_dirent_lock);
1681 spin_unlock(&configfs_dirent_lock);
1685 static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1687 struct dentry * dentry = file->f_path.dentry;
1691 offset += file->f_pos;
1700 if (offset != file->f_pos) {
1701 file->f_pos = offset;
1702 if (file->f_pos >= 2) {
1703 struct configfs_dirent *sd = dentry->d_fsdata;
1704 struct configfs_dirent *cursor = file->private_data;
1705 struct list_head *p;
1706 loff_t n = file->f_pos - 2;
1708 spin_lock(&configfs_dirent_lock);
1709 list_del(&cursor->s_sibling);
1710 p = sd->s_children.next;
1711 while (n && p != &sd->s_children) {
1712 struct configfs_dirent *next;
1713 next = list_entry(p, struct configfs_dirent,
1715 if (next->s_element)
1719 list_add_tail(&cursor->s_sibling, p);
1720 spin_unlock(&configfs_dirent_lock);
1726 const struct file_operations configfs_dir_operations = {
1727 .open = configfs_dir_open,
1728 .release = configfs_dir_close,
1729 .llseek = configfs_dir_lseek,
1730 .read = generic_read_dir,
1731 .iterate_shared = configfs_readdir,
1735 * configfs_register_group - creates a parent-child relation between two groups
1736 * @parent_group: parent group
1737 * @group: child group
1739 * link groups, creates dentry for the child and attaches it to the
1742 * Return: 0 on success, negative errno code on error
1744 int configfs_register_group(struct config_group *parent_group,
1745 struct config_group *group)
1747 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1748 struct dentry *parent;
1749 struct configfs_fragment *frag;
1752 frag = new_fragment();
1756 mutex_lock(&subsys->su_mutex);
1757 link_group(parent_group, group);
1758 mutex_unlock(&subsys->su_mutex);
1760 parent = parent_group->cg_item.ci_dentry;
1762 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1763 ret = create_default_group(parent_group, group, frag);
1767 spin_lock(&configfs_dirent_lock);
1768 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1769 spin_unlock(&configfs_dirent_lock);
1770 inode_unlock(d_inode(parent));
1774 inode_unlock(d_inode(parent));
1775 mutex_lock(&subsys->su_mutex);
1776 unlink_group(group);
1777 mutex_unlock(&subsys->su_mutex);
1781 EXPORT_SYMBOL(configfs_register_group);
1784 * configfs_unregister_group() - unregisters a child group from its parent
1785 * @group: parent group to be unregistered
1787 * Undoes configfs_register_group()
1789 void configfs_unregister_group(struct config_group *group)
1791 struct configfs_subsystem *subsys = group->cg_subsys;
1792 struct dentry *dentry = group->cg_item.ci_dentry;
1793 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1794 struct configfs_dirent *sd = dentry->d_fsdata;
1795 struct configfs_fragment *frag = sd->s_frag;
1797 down_write(&frag->frag_sem);
1798 frag->frag_dead = true;
1799 up_write(&frag->frag_sem);
1801 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1802 spin_lock(&configfs_dirent_lock);
1803 configfs_detach_prep(dentry, NULL);
1804 spin_unlock(&configfs_dirent_lock);
1806 configfs_detach_group(&group->cg_item);
1807 d_inode(dentry)->i_flags |= S_DEAD;
1809 fsnotify_rmdir(d_inode(parent), dentry);
1811 inode_unlock(d_inode(parent));
1815 mutex_lock(&subsys->su_mutex);
1816 unlink_group(group);
1817 mutex_unlock(&subsys->su_mutex);
1819 EXPORT_SYMBOL(configfs_unregister_group);
1822 * configfs_register_default_group() - allocates and registers a child group
1823 * @parent_group: parent group
1824 * @name: child group name
1825 * @item_type: child item type description
1827 * boilerplate to allocate and register a child group with its parent. We need
1828 * kzalloc'ed memory because child's default_group is initially empty.
1830 * Return: allocated config group or ERR_PTR() on error
1832 struct config_group *
1833 configfs_register_default_group(struct config_group *parent_group,
1835 const struct config_item_type *item_type)
1838 struct config_group *group;
1840 group = kzalloc(sizeof(*group), GFP_KERNEL);
1842 return ERR_PTR(-ENOMEM);
1843 config_group_init_type_name(group, name, item_type);
1845 ret = configfs_register_group(parent_group, group);
1848 return ERR_PTR(ret);
1852 EXPORT_SYMBOL(configfs_register_default_group);
1855 * configfs_unregister_default_group() - unregisters and frees a child group
1856 * @group: the group to act on
1858 void configfs_unregister_default_group(struct config_group *group)
1860 configfs_unregister_group(group);
1863 EXPORT_SYMBOL(configfs_unregister_default_group);
1865 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1868 struct config_group *group = &subsys->su_group;
1869 struct dentry *dentry;
1870 struct dentry *root;
1871 struct configfs_dirent *sd;
1872 struct configfs_fragment *frag;
1874 frag = new_fragment();
1878 root = configfs_pin_fs();
1881 return PTR_ERR(root);
1884 if (!group->cg_item.ci_name)
1885 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1887 sd = root->d_fsdata;
1888 link_group(to_config_group(sd->s_element), group);
1890 inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
1893 dentry = d_alloc_name(root, group->cg_item.ci_name);
1895 d_add(dentry, NULL);
1897 err = configfs_attach_group(sd->s_element, &group->cg_item,
1900 BUG_ON(d_inode(dentry));
1904 spin_lock(&configfs_dirent_lock);
1905 configfs_dir_set_ready(dentry->d_fsdata);
1906 spin_unlock(&configfs_dirent_lock);
1910 inode_unlock(d_inode(root));
1913 unlink_group(group);
1914 configfs_release_fs();
1921 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1923 struct config_group *group = &subsys->su_group;
1924 struct dentry *dentry = group->cg_item.ci_dentry;
1925 struct dentry *root = dentry->d_sb->s_root;
1926 struct configfs_dirent *sd = dentry->d_fsdata;
1927 struct configfs_fragment *frag = sd->s_frag;
1929 if (dentry->d_parent != root) {
1930 pr_err("Tried to unregister non-subsystem!\n");
1934 down_write(&frag->frag_sem);
1935 frag->frag_dead = true;
1936 up_write(&frag->frag_sem);
1938 inode_lock_nested(d_inode(root),
1940 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
1941 mutex_lock(&configfs_symlink_mutex);
1942 spin_lock(&configfs_dirent_lock);
1943 if (configfs_detach_prep(dentry, NULL)) {
1944 pr_err("Tried to unregister non-empty subsystem!\n");
1946 spin_unlock(&configfs_dirent_lock);
1947 mutex_unlock(&configfs_symlink_mutex);
1948 configfs_detach_group(&group->cg_item);
1949 d_inode(dentry)->i_flags |= S_DEAD;
1951 fsnotify_rmdir(d_inode(root), dentry);
1952 inode_unlock(d_inode(dentry));
1956 inode_unlock(d_inode(root));
1960 unlink_group(group);
1961 configfs_release_fs();
1964 EXPORT_SYMBOL(configfs_register_subsystem);
1965 EXPORT_SYMBOL(configfs_unregister_subsystem);