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);
40 * All of link_obj/unlink_obj/link_group/unlink_group require that
41 * subsys->su_mutex is held.
42 * But parent configfs_subsystem is NULL when config_item is root.
43 * Use this mutex when config_item is root.
45 static DEFINE_MUTEX(configfs_subsystem_mutex);
47 static void configfs_d_iput(struct dentry * dentry,
50 struct configfs_dirent *sd = dentry->d_fsdata;
53 /* Coordinate with configfs_readdir */
54 spin_lock(&configfs_dirent_lock);
56 * Set sd->s_dentry to null only when this dentry is the one
57 * that is going to be killed. Otherwise configfs_d_iput may
58 * run just after configfs_attach_attr and set sd->s_dentry to
59 * NULL even it's still in use.
61 if (sd->s_dentry == dentry)
64 spin_unlock(&configfs_dirent_lock);
70 const struct dentry_operations configfs_dentry_ops = {
71 .d_iput = configfs_d_iput,
72 .d_delete = always_delete_dentry,
78 * Helpers to make lockdep happy with our recursive locking of default groups'
79 * inodes (see configfs_attach_group() and configfs_detach_group()).
80 * We put default groups i_mutexes in separate classes according to their depth
81 * from the youngest non-default group ancestor.
83 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
84 * groups A/B and A/C will have their inode's mutex in class
85 * default_group_class[0], and default group A/C/D will be in
86 * default_group_class[1].
88 * The lock classes are declared and assigned in inode.c, according to the
90 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
91 * default groups, and reset to -1 when all default groups are attached. During
92 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
93 * inode's mutex is set to default_group_class[s_depth - 1].
96 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
101 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
102 struct configfs_dirent *sd)
104 int parent_depth = parent_sd->s_depth;
106 if (parent_depth >= 0)
107 sd->s_depth = parent_depth + 1;
111 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
114 * item's i_mutex class is already setup, so s_depth is now only
115 * used to set new sub-directories s_depth, which is always done
116 * with item's i_mutex locked.
119 * sd->s_depth == -1 iff we are a non default group.
120 * else (we are a default group) sd->s_depth > 0 (see
123 if (sd->s_depth == -1)
125 * We are a non default group and we are going to create
132 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
134 /* We will not create default groups anymore. */
138 #else /* CONFIG_LOCKDEP */
140 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
144 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
145 struct configfs_dirent *sd)
150 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
155 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
159 #endif /* CONFIG_LOCKDEP */
161 static struct configfs_fragment *new_fragment(void)
163 struct configfs_fragment *p;
165 p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL);
167 atomic_set(&p->frag_count, 1);
168 init_rwsem(&p->frag_sem);
169 p->frag_dead = false;
174 void put_fragment(struct configfs_fragment *frag)
176 if (frag && atomic_dec_and_test(&frag->frag_count))
180 struct configfs_fragment *get_fragment(struct configfs_fragment *frag)
183 atomic_inc(&frag->frag_count);
188 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
190 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
191 void *element, int type,
192 struct configfs_fragment *frag)
194 struct configfs_dirent * sd;
196 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
198 return ERR_PTR(-ENOMEM);
200 atomic_set(&sd->s_count, 1);
201 INIT_LIST_HEAD(&sd->s_children);
202 sd->s_element = element;
204 configfs_init_dirent_depth(sd);
205 spin_lock(&configfs_dirent_lock);
206 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
207 spin_unlock(&configfs_dirent_lock);
208 kmem_cache_free(configfs_dir_cachep, sd);
209 return ERR_PTR(-ENOENT);
211 sd->s_frag = get_fragment(frag);
212 list_add(&sd->s_sibling, &parent_sd->s_children);
213 spin_unlock(&configfs_dirent_lock);
220 * Return -EEXIST if there is already a configfs element with the same
221 * name for the same parent.
223 * called with parent inode's i_mutex held
225 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
226 const unsigned char *new)
228 struct configfs_dirent * sd;
230 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
232 const unsigned char *existing = configfs_get_name(sd);
233 if (strcmp(existing, new))
244 int configfs_make_dirent(struct configfs_dirent * parent_sd,
245 struct dentry * dentry, void * element,
246 umode_t mode, int type, struct configfs_fragment *frag)
248 struct configfs_dirent * sd;
250 sd = configfs_new_dirent(parent_sd, element, type, frag);
255 sd->s_dentry = dentry;
257 dentry->d_fsdata = configfs_get(sd);
262 static void configfs_remove_dirent(struct dentry *dentry)
264 struct configfs_dirent *sd = dentry->d_fsdata;
268 spin_lock(&configfs_dirent_lock);
269 list_del_init(&sd->s_sibling);
270 spin_unlock(&configfs_dirent_lock);
275 * configfs_create_dir - create a directory for an config_item.
276 * @item: config_itemwe're creating directory for.
277 * @dentry: config_item's dentry.
279 * Note: user-created entries won't be allowed under this new directory
280 * until it is validated by configfs_dir_set_ready()
283 static int configfs_create_dir(struct config_item *item, struct dentry *dentry,
284 struct configfs_fragment *frag)
287 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
288 struct dentry *p = dentry->d_parent;
293 error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
297 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
298 CONFIGFS_DIR | CONFIGFS_USET_CREATING,
303 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
304 inode = configfs_create(dentry, mode);
308 inode->i_op = &configfs_dir_inode_operations;
309 inode->i_fop = &configfs_dir_operations;
310 /* directory inodes start off with i_nlink == 2 (for "." entry) */
312 d_instantiate(dentry, inode);
314 dget(dentry); /* pin directory dentries in core */
315 inc_nlink(d_inode(p));
316 item->ci_dentry = dentry;
320 configfs_remove_dirent(dentry);
321 return PTR_ERR(inode);
325 * Allow userspace to create new entries under a new directory created with
326 * configfs_create_dir(), and under all of its chidlren directories recursively.
327 * @sd configfs_dirent of the new directory to validate
329 * Caller must hold configfs_dirent_lock.
331 static void configfs_dir_set_ready(struct configfs_dirent *sd)
333 struct configfs_dirent *child_sd;
335 sd->s_type &= ~CONFIGFS_USET_CREATING;
336 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
337 if (child_sd->s_type & CONFIGFS_USET_CREATING)
338 configfs_dir_set_ready(child_sd);
342 * Check that a directory does not belong to a directory hierarchy being
343 * attached and not validated yet.
344 * @sd configfs_dirent of the directory to check
346 * @return non-zero iff the directory was validated
348 * Note: takes configfs_dirent_lock, so the result may change from false to true
349 * in two consecutive calls, but never from true to false.
351 int configfs_dirent_is_ready(struct configfs_dirent *sd)
355 spin_lock(&configfs_dirent_lock);
356 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
357 spin_unlock(&configfs_dirent_lock);
362 int configfs_create_link(struct configfs_dirent *target, struct dentry *parent,
363 struct dentry *dentry, char *body)
366 umode_t mode = S_IFLNK | S_IRWXUGO;
367 struct configfs_dirent *p = parent->d_fsdata;
370 err = configfs_make_dirent(p, dentry, target, mode, CONFIGFS_ITEM_LINK,
375 inode = configfs_create(dentry, mode);
379 inode->i_link = body;
380 inode->i_op = &configfs_symlink_inode_operations;
381 d_instantiate(dentry, inode);
382 dget(dentry); /* pin link dentries in core */
386 configfs_remove_dirent(dentry);
387 return PTR_ERR(inode);
390 static void remove_dir(struct dentry * d)
392 struct dentry * parent = dget(d->d_parent);
394 configfs_remove_dirent(d);
396 if (d_really_is_positive(d))
397 simple_rmdir(d_inode(parent),d);
399 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
405 * configfs_remove_dir - remove an config_item's directory.
406 * @item: config_item we're removing.
408 * The only thing special about this is that we remove any files in
409 * the directory before we remove the directory, and we've inlined
410 * what used to be configfs_rmdir() below, instead of calling separately.
412 * Caller holds the mutex of the item's inode
415 static void configfs_remove_dir(struct config_item * item)
417 struct dentry * dentry = dget(item->ci_dentry);
424 * Drop reference from dget() on entrance.
430 /* attaches attribute's configfs_dirent to the dentry corresponding to the
433 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
435 struct configfs_attribute * attr = sd->s_element;
438 spin_lock(&configfs_dirent_lock);
439 dentry->d_fsdata = configfs_get(sd);
440 sd->s_dentry = dentry;
441 spin_unlock(&configfs_dirent_lock);
443 inode = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG);
446 return PTR_ERR(inode);
448 if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) {
450 inode->i_fop = &configfs_bin_file_operations;
452 inode->i_size = PAGE_SIZE;
453 inode->i_fop = &configfs_file_operations;
455 d_add(dentry, inode);
459 static struct dentry * configfs_lookup(struct inode *dir,
460 struct dentry *dentry,
463 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
464 struct configfs_dirent * sd;
469 * Fake invisibility if dir belongs to a group/default groups hierarchy
472 * This forbids userspace to read/write attributes of items which may
473 * not complete their initialization, since the dentries of the
474 * attributes won't be instantiated.
477 if (!configfs_dirent_is_ready(parent_sd))
480 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
481 if (sd->s_type & CONFIGFS_NOT_PINNED) {
482 const unsigned char * name = configfs_get_name(sd);
484 if (strcmp(name, dentry->d_name.name))
488 err = configfs_attach_attr(sd, dentry);
495 * If it doesn't exist and it isn't a NOT_PINNED item,
496 * it must be negative.
498 if (dentry->d_name.len > NAME_MAX)
499 return ERR_PTR(-ENAMETOOLONG);
509 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
510 * attributes and are removed by rmdir(). We recurse, setting
511 * CONFIGFS_USET_DROPPING on all children that are candidates for
513 * If there is an error, the caller will reset the flags via
514 * configfs_detach_rollback().
516 static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait)
518 struct configfs_dirent *parent_sd = dentry->d_fsdata;
519 struct configfs_dirent *sd;
522 /* Mark that we're trying to drop the group */
523 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
526 if (parent_sd->s_links)
530 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
531 if (!sd->s_element ||
532 (sd->s_type & CONFIGFS_NOT_PINNED))
534 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
535 /* Abort if racing with mkdir() */
536 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
538 *wait= dget(sd->s_dentry);
543 * Yup, recursive. If there's a problem, blame
544 * deep nesting of default_groups
546 ret = configfs_detach_prep(sd->s_dentry, wait);
560 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
563 static void configfs_detach_rollback(struct dentry *dentry)
565 struct configfs_dirent *parent_sd = dentry->d_fsdata;
566 struct configfs_dirent *sd;
568 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
570 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
571 if (sd->s_type & CONFIGFS_USET_DEFAULT)
572 configfs_detach_rollback(sd->s_dentry);
575 static void detach_attrs(struct config_item * item)
577 struct dentry * dentry = dget(item->ci_dentry);
578 struct configfs_dirent * parent_sd;
579 struct configfs_dirent * sd, * tmp;
584 pr_debug("configfs %s: dropping attrs for dir\n",
585 dentry->d_name.name);
587 parent_sd = dentry->d_fsdata;
588 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
589 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
591 spin_lock(&configfs_dirent_lock);
592 list_del_init(&sd->s_sibling);
593 spin_unlock(&configfs_dirent_lock);
594 configfs_drop_dentry(sd, dentry);
599 * Drop reference from dget() on entrance.
604 static int populate_attrs(struct config_item *item)
606 const struct config_item_type *t = item->ci_type;
607 struct configfs_attribute *attr;
608 struct configfs_bin_attribute *bin_attr;
615 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
616 if ((error = configfs_create_file(item, attr)))
620 if (t->ct_bin_attrs) {
621 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
622 error = configfs_create_bin_file(item, bin_attr);
634 static int configfs_attach_group(struct config_item *parent_item,
635 struct config_item *item,
636 struct dentry *dentry,
637 struct configfs_fragment *frag);
638 static void configfs_detach_group(struct config_item *item);
640 static void detach_groups(struct config_group *group)
642 struct dentry * dentry = dget(group->cg_item.ci_dentry);
643 struct dentry *child;
644 struct configfs_dirent *parent_sd;
645 struct configfs_dirent *sd, *tmp;
650 parent_sd = dentry->d_fsdata;
651 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
652 if (!sd->s_element ||
653 !(sd->s_type & CONFIGFS_USET_DEFAULT))
656 child = sd->s_dentry;
658 inode_lock(d_inode(child));
660 configfs_detach_group(sd->s_element);
661 d_inode(child)->i_flags |= S_DEAD;
664 inode_unlock(d_inode(child));
671 * Drop reference from dget() on entrance.
677 * This fakes mkdir(2) on a default_groups[] entry. It
678 * creates a dentry, attachs it, and then does fixup
681 * We could, perhaps, tweak our parent's ->mkdir for a minute and
682 * try using vfs_mkdir. Just a thought.
684 static int create_default_group(struct config_group *parent_group,
685 struct config_group *group,
686 struct configfs_fragment *frag)
689 struct configfs_dirent *sd;
690 /* We trust the caller holds a reference to parent */
691 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
693 if (!group->cg_item.ci_name)
694 group->cg_item.ci_name = group->cg_item.ci_namebuf;
697 child = d_alloc_name(parent, group->cg_item.ci_name);
701 ret = configfs_attach_group(&parent_group->cg_item,
702 &group->cg_item, child, frag);
704 sd = child->d_fsdata;
705 sd->s_type |= CONFIGFS_USET_DEFAULT;
707 BUG_ON(d_inode(child));
716 static int populate_groups(struct config_group *group,
717 struct configfs_fragment *frag)
719 struct config_group *new_group;
722 list_for_each_entry(new_group, &group->default_groups, group_entry) {
723 ret = create_default_group(group, new_group, frag);
725 detach_groups(group);
733 void configfs_remove_default_groups(struct config_group *group)
735 struct config_group *g, *n;
737 list_for_each_entry_safe(g, n, &group->default_groups, group_entry) {
738 list_del(&g->group_entry);
739 config_item_put(&g->cg_item);
742 EXPORT_SYMBOL(configfs_remove_default_groups);
745 * All of link_obj/unlink_obj/link_group/unlink_group require that
746 * subsys->su_mutex is held.
749 static void unlink_obj(struct config_item *item)
751 struct config_group *group;
753 group = item->ci_group;
755 list_del_init(&item->ci_entry);
757 item->ci_group = NULL;
758 item->ci_parent = NULL;
760 /* Drop the reference for ci_entry */
761 config_item_put(item);
763 /* Drop the reference for ci_parent */
764 config_group_put(group);
768 static void link_obj(struct config_item *parent_item, struct config_item *item)
771 * Parent seems redundant with group, but it makes certain
772 * traversals much nicer.
774 item->ci_parent = parent_item;
777 * We hold a reference on the parent for the child's ci_parent
780 item->ci_group = config_group_get(to_config_group(parent_item));
781 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
784 * We hold a reference on the child for ci_entry on the parent's
787 config_item_get(item);
790 static void unlink_group(struct config_group *group)
792 struct config_group *new_group;
794 list_for_each_entry(new_group, &group->default_groups, group_entry)
795 unlink_group(new_group);
797 group->cg_subsys = NULL;
798 unlink_obj(&group->cg_item);
801 static void link_group(struct config_group *parent_group, struct config_group *group)
803 struct config_group *new_group;
804 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
806 link_obj(&parent_group->cg_item, &group->cg_item);
808 if (parent_group->cg_subsys)
809 subsys = parent_group->cg_subsys;
810 else if (configfs_is_root(&parent_group->cg_item))
811 subsys = to_configfs_subsystem(group);
814 group->cg_subsys = subsys;
816 list_for_each_entry(new_group, &group->default_groups, group_entry)
817 link_group(group, new_group);
821 * The goal is that configfs_attach_item() (and
822 * configfs_attach_group()) can be called from either the VFS or this
823 * module. That is, they assume that the items have been created,
824 * the dentry allocated, and the dcache is all ready to go.
826 * If they fail, they must clean up after themselves as if they
827 * had never been called. The caller (VFS or local function) will
828 * handle cleaning up the dcache bits.
830 * configfs_detach_group() and configfs_detach_item() behave similarly on
831 * the way out. They assume that the proper semaphores are held, they
832 * clean up the configfs items, and they expect their callers will
833 * handle the dcache bits.
835 static int configfs_attach_item(struct config_item *parent_item,
836 struct config_item *item,
837 struct dentry *dentry,
838 struct configfs_fragment *frag)
842 ret = configfs_create_dir(item, dentry, frag);
844 ret = populate_attrs(item);
847 * We are going to remove an inode and its dentry but
848 * the VFS may already have hit and used them. Thus,
849 * we must lock them as rmdir() would.
851 inode_lock(d_inode(dentry));
852 configfs_remove_dir(item);
853 d_inode(dentry)->i_flags |= S_DEAD;
855 inode_unlock(d_inode(dentry));
863 /* Caller holds the mutex of the item's inode */
864 static void configfs_detach_item(struct config_item *item)
867 configfs_remove_dir(item);
870 static int configfs_attach_group(struct config_item *parent_item,
871 struct config_item *item,
872 struct dentry *dentry,
873 struct configfs_fragment *frag)
876 struct configfs_dirent *sd;
878 ret = configfs_attach_item(parent_item, item, dentry, frag);
880 sd = dentry->d_fsdata;
881 sd->s_type |= CONFIGFS_USET_DIR;
884 * FYI, we're faking mkdir in populate_groups()
885 * We must lock the group's inode to avoid races with the VFS
886 * which can already hit the inode and try to add/remove entries
889 * We must also lock the inode to remove it safely in case of
890 * error, as rmdir() would.
892 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
893 configfs_adjust_dir_dirent_depth_before_populate(sd);
894 ret = populate_groups(to_config_group(item), frag);
896 configfs_detach_item(item);
897 d_inode(dentry)->i_flags |= S_DEAD;
900 configfs_adjust_dir_dirent_depth_after_populate(sd);
901 inode_unlock(d_inode(dentry));
909 /* Caller holds the mutex of the group's inode */
910 static void configfs_detach_group(struct config_item *item)
912 detach_groups(to_config_group(item));
913 configfs_detach_item(item);
917 * After the item has been detached from the filesystem view, we are
918 * ready to tear it out of the hierarchy. Notify the client before
919 * we do that so they can perform any cleanup that requires
920 * navigating the hierarchy. A client does not need to provide this
921 * callback. The subsystem semaphore MUST be held by the caller, and
922 * references must be valid for both items. It also assumes the
923 * caller has validated ci_type.
925 static void client_disconnect_notify(struct config_item *parent_item,
926 struct config_item *item)
928 const struct config_item_type *type;
930 type = parent_item->ci_type;
933 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
934 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
939 * Drop the initial reference from make_item()/make_group()
940 * This function assumes that reference is held on item
941 * and that item holds a valid reference to the parent. Also, it
942 * assumes the caller has validated ci_type.
944 static void client_drop_item(struct config_item *parent_item,
945 struct config_item *item)
947 const struct config_item_type *type;
949 type = parent_item->ci_type;
953 * If ->drop_item() exists, it is responsible for the
956 if (type->ct_group_ops && type->ct_group_ops->drop_item)
957 type->ct_group_ops->drop_item(to_config_group(parent_item),
960 config_item_put(item);
964 static void configfs_dump_one(struct configfs_dirent *sd, int level)
966 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
968 #define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type);
969 type_print(CONFIGFS_ROOT);
970 type_print(CONFIGFS_DIR);
971 type_print(CONFIGFS_ITEM_ATTR);
972 type_print(CONFIGFS_ITEM_LINK);
973 type_print(CONFIGFS_USET_DIR);
974 type_print(CONFIGFS_USET_DEFAULT);
975 type_print(CONFIGFS_USET_DROPPING);
979 static int configfs_dump(struct configfs_dirent *sd, int level)
981 struct configfs_dirent *child_sd;
984 configfs_dump_one(sd, level);
986 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
989 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
990 ret = configfs_dump(child_sd, level + 2);
1001 * configfs_depend_item() and configfs_undepend_item()
1003 * WARNING: Do not call these from a configfs callback!
1005 * This describes these functions and their helpers.
1007 * Allow another kernel system to depend on a config_item. If this
1008 * happens, the item cannot go away until the dependent can live without
1009 * it. The idea is to give client modules as simple an interface as
1010 * possible. When a system asks them to depend on an item, they just
1011 * call configfs_depend_item(). If the item is live and the client
1012 * driver is in good shape, we'll happily do the work for them.
1014 * Why is the locking complex? Because configfs uses the VFS to handle
1015 * all locking, but this function is called outside the normal
1016 * VFS->configfs path. So it must take VFS locks to prevent the
1017 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1018 * why you can't call these functions underneath configfs callbacks.
1020 * Note, btw, that this can be called at *any* time, even when a configfs
1021 * subsystem isn't registered, or when configfs is loading or unloading.
1022 * Just like configfs_register_subsystem(). So we take the same
1023 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1024 * If we can find the target item in the
1025 * configfs tree, it must be part of the subsystem tree as well, so we
1026 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1027 * locking out mkdir() and rmdir(), who might be racing us.
1031 * configfs_depend_prep()
1033 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1034 * attributes. This is similar but not the same to configfs_detach_prep().
1035 * Note that configfs_detach_prep() expects the parent to be locked when it
1036 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1037 * do that so we can unlock it if we find nothing.
1039 * Here we do a depth-first search of the dentry hierarchy looking for
1041 * We deliberately ignore items tagged as dropping since they are virtually
1042 * dead, as well as items in the middle of attachment since they virtually
1043 * do not exist yet. This completes the locking out of racing mkdir() and
1045 * Note: subdirectories in the middle of attachment start with s_type =
1046 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1047 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1048 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1050 * If the target is not found, -ENOENT is bubbled up.
1052 * This adds a requirement that all config_items be unique!
1054 * This is recursive. There isn't
1055 * much on the stack, though, so folks that need this function - be careful
1056 * about your stack! Patches will be accepted to make it iterative.
1058 static int configfs_depend_prep(struct dentry *origin,
1059 struct config_item *target)
1061 struct configfs_dirent *child_sd, *sd;
1064 BUG_ON(!origin || !origin->d_fsdata);
1065 sd = origin->d_fsdata;
1067 if (sd->s_element == target) /* Boo-yah */
1070 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1071 if ((child_sd->s_type & CONFIGFS_DIR) &&
1072 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1073 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1074 ret = configfs_depend_prep(child_sd->s_dentry,
1077 goto out; /* Child path boo-yah */
1081 /* We looped all our children and didn't find target */
1088 static int configfs_do_depend_item(struct dentry *subsys_dentry,
1089 struct config_item *target)
1091 struct configfs_dirent *p;
1094 spin_lock(&configfs_dirent_lock);
1095 /* Scan the tree, return 0 if found */
1096 ret = configfs_depend_prep(subsys_dentry, target);
1098 goto out_unlock_dirent_lock;
1101 * We are sure that the item is not about to be removed by rmdir(), and
1102 * not in the middle of attachment by mkdir().
1104 p = target->ci_dentry->d_fsdata;
1105 p->s_dependent_count += 1;
1107 out_unlock_dirent_lock:
1108 spin_unlock(&configfs_dirent_lock);
1113 static inline struct configfs_dirent *
1114 configfs_find_subsys_dentry(struct configfs_dirent *root_sd,
1115 struct config_item *subsys_item)
1117 struct configfs_dirent *p;
1118 struct configfs_dirent *ret = NULL;
1120 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1121 if (p->s_type & CONFIGFS_DIR &&
1122 p->s_element == subsys_item) {
1132 int configfs_depend_item(struct configfs_subsystem *subsys,
1133 struct config_item *target)
1136 struct configfs_dirent *subsys_sd;
1137 struct config_item *s_item = &subsys->su_group.cg_item;
1138 struct dentry *root;
1141 * Pin the configfs filesystem. This means we can safely access
1142 * the root of the configfs filesystem.
1144 root = configfs_pin_fs();
1146 return PTR_ERR(root);
1149 * Next, lock the root directory. We're going to check that the
1150 * subsystem is really registered, and so we need to lock out
1151 * configfs_[un]register_subsystem().
1153 inode_lock(d_inode(root));
1155 subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item);
1161 /* Ok, now we can trust subsys/s_item */
1162 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1165 inode_unlock(d_inode(root));
1168 * If we succeeded, the fs is pinned via other methods. If not,
1169 * we're done with it anyway. So release_fs() is always right.
1171 configfs_release_fs();
1175 EXPORT_SYMBOL(configfs_depend_item);
1178 * Release the dependent linkage. This is much simpler than
1179 * configfs_depend_item() because we know that the client driver is
1180 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1182 void configfs_undepend_item(struct config_item *target)
1184 struct configfs_dirent *sd;
1187 * Since we can trust everything is pinned, we just need
1188 * configfs_dirent_lock.
1190 spin_lock(&configfs_dirent_lock);
1192 sd = target->ci_dentry->d_fsdata;
1193 BUG_ON(sd->s_dependent_count < 1);
1195 sd->s_dependent_count -= 1;
1198 * After this unlock, we cannot trust the item to stay alive!
1199 * DO NOT REFERENCE item after this unlock.
1201 spin_unlock(&configfs_dirent_lock);
1203 EXPORT_SYMBOL(configfs_undepend_item);
1206 * caller_subsys is a caller's subsystem not target's. This is used to
1207 * determine if we should lock root and check subsys or not. When we are
1208 * in the same subsystem as our target there is no need to do locking as
1209 * we know that subsys is valid and is not unregistered during this function
1210 * as we are called from callback of one of his children and VFS holds a lock
1211 * on some inode. Otherwise we have to lock our root to ensure that target's
1212 * subsystem it is not unregistered during this function.
1214 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
1215 struct config_item *target)
1217 struct configfs_subsystem *target_subsys;
1218 struct config_group *root, *parent;
1219 struct configfs_dirent *subsys_sd;
1222 /* Disallow this function for configfs root */
1223 if (configfs_is_root(target))
1226 parent = target->ci_group;
1228 * This may happen when someone is trying to depend root
1229 * directory of some subsystem
1231 if (configfs_is_root(&parent->cg_item)) {
1232 target_subsys = to_configfs_subsystem(to_config_group(target));
1235 target_subsys = parent->cg_subsys;
1236 /* Find a cofnigfs root as we may need it for locking */
1237 for (root = parent; !configfs_is_root(&root->cg_item);
1238 root = root->cg_item.ci_group)
1242 if (target_subsys != caller_subsys) {
1244 * We are in other configfs subsystem, so we have to do
1245 * additional locking to prevent other subsystem from being
1248 inode_lock(d_inode(root->cg_item.ci_dentry));
1251 * As we are trying to depend item from other subsystem
1252 * we have to check if this subsystem is still registered
1254 subsys_sd = configfs_find_subsys_dentry(
1255 root->cg_item.ci_dentry->d_fsdata,
1256 &target_subsys->su_group.cg_item);
1258 goto out_root_unlock;
1260 subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata;
1263 /* Now we can execute core of depend item */
1264 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1266 if (target_subsys != caller_subsys)
1269 * We were called from subsystem other than our target so we
1270 * took some locks so now it's time to release them
1272 inode_unlock(d_inode(root->cg_item.ci_dentry));
1276 EXPORT_SYMBOL(configfs_depend_item_unlocked);
1278 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1282 struct config_group *group = NULL;
1283 struct config_item *item = NULL;
1284 struct config_item *parent_item;
1285 struct configfs_subsystem *subsys;
1286 struct configfs_dirent *sd;
1287 const struct config_item_type *type;
1288 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1289 struct configfs_fragment *frag;
1292 sd = dentry->d_parent->d_fsdata;
1295 * Fake invisibility if dir belongs to a group/default groups hierarchy
1298 if (!configfs_dirent_is_ready(sd)) {
1303 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1308 frag = new_fragment();
1314 /* Get a working ref for the duration of this function */
1315 parent_item = configfs_get_config_item(dentry->d_parent);
1316 type = parent_item->ci_type;
1317 subsys = to_config_group(parent_item)->cg_subsys;
1320 if (!type || !type->ct_group_ops ||
1321 (!type->ct_group_ops->make_group &&
1322 !type->ct_group_ops->make_item)) {
1323 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1328 * The subsystem may belong to a different module than the item
1329 * being created. We don't want to safely pin the new item but
1330 * fail to pin the subsystem it sits under.
1332 if (!subsys->su_group.cg_item.ci_type) {
1336 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1337 if (!try_module_get(subsys_owner)) {
1342 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1345 goto out_subsys_put;
1348 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1350 mutex_lock(&subsys->su_mutex);
1351 if (type->ct_group_ops->make_group) {
1352 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1354 group = ERR_PTR(-ENOMEM);
1355 if (!IS_ERR(group)) {
1356 link_group(to_config_group(parent_item), group);
1357 item = &group->cg_item;
1359 ret = PTR_ERR(group);
1361 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1363 item = ERR_PTR(-ENOMEM);
1365 link_obj(parent_item, item);
1367 ret = PTR_ERR(item);
1369 mutex_unlock(&subsys->su_mutex);
1374 * If ret != 0, then link_obj() was never called.
1375 * There are no extra references to clean up.
1377 goto out_subsys_put;
1381 * link_obj() has been called (via link_group() for groups).
1382 * From here on out, errors must clean that up.
1385 type = item->ci_type;
1391 new_item_owner = type->ct_owner;
1392 if (!try_module_get(new_item_owner)) {
1398 * I hate doing it this way, but if there is
1399 * an error, module_put() probably should
1400 * happen after any cleanup.
1405 * Make racing rmdir() fail if it did not tag parent with
1406 * CONFIGFS_USET_DROPPING
1407 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1408 * fail and let rmdir() terminate correctly
1410 spin_lock(&configfs_dirent_lock);
1411 /* This will make configfs_detach_prep() fail */
1412 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1413 spin_unlock(&configfs_dirent_lock);
1416 ret = configfs_attach_group(parent_item, item, dentry, frag);
1418 ret = configfs_attach_item(parent_item, item, dentry, frag);
1420 spin_lock(&configfs_dirent_lock);
1421 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1423 configfs_dir_set_ready(dentry->d_fsdata);
1424 spin_unlock(&configfs_dirent_lock);
1428 /* Tear down everything we built up */
1429 mutex_lock(&subsys->su_mutex);
1431 client_disconnect_notify(parent_item, item);
1433 unlink_group(group);
1436 client_drop_item(parent_item, item);
1438 mutex_unlock(&subsys->su_mutex);
1441 module_put(new_item_owner);
1446 module_put(subsys_owner);
1450 * link_obj()/link_group() took a reference from child->parent,
1451 * so the parent is safely pinned. We can drop our working
1454 config_item_put(parent_item);
1461 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1463 struct config_item *parent_item;
1464 struct config_item *item;
1465 struct configfs_subsystem *subsys;
1466 struct configfs_dirent *sd;
1467 struct configfs_fragment *frag;
1468 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1471 sd = dentry->d_fsdata;
1472 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1475 /* Get a working ref until we have the child */
1476 parent_item = configfs_get_config_item(dentry->d_parent);
1477 subsys = to_config_group(parent_item)->cg_subsys;
1480 if (!parent_item->ci_type) {
1481 config_item_put(parent_item);
1485 /* configfs_mkdir() shouldn't have allowed this */
1486 BUG_ON(!subsys->su_group.cg_item.ci_type);
1487 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1490 * Ensure that no racing symlink() will make detach_prep() fail while
1491 * the new link is temporarily attached
1494 struct dentry *wait;
1496 mutex_lock(&configfs_symlink_mutex);
1497 spin_lock(&configfs_dirent_lock);
1499 * Here's where we check for dependents. We're protected by
1500 * configfs_dirent_lock.
1501 * If no dependent, atomically tag the item as dropping.
1503 ret = sd->s_dependent_count ? -EBUSY : 0;
1505 ret = configfs_detach_prep(dentry, &wait);
1507 configfs_detach_rollback(dentry);
1509 spin_unlock(&configfs_dirent_lock);
1510 mutex_unlock(&configfs_symlink_mutex);
1513 if (ret != -EAGAIN) {
1514 config_item_put(parent_item);
1518 /* Wait until the racing operation terminates */
1519 inode_lock(d_inode(wait));
1520 inode_unlock(d_inode(wait));
1523 } while (ret == -EAGAIN);
1526 if (down_write_killable(&frag->frag_sem)) {
1527 spin_lock(&configfs_dirent_lock);
1528 configfs_detach_rollback(dentry);
1529 spin_unlock(&configfs_dirent_lock);
1530 config_item_put(parent_item);
1533 frag->frag_dead = true;
1534 up_write(&frag->frag_sem);
1536 /* Get a working ref for the duration of this function */
1537 item = configfs_get_config_item(dentry);
1539 /* Drop reference from above, item already holds one. */
1540 config_item_put(parent_item);
1543 dead_item_owner = item->ci_type->ct_owner;
1545 if (sd->s_type & CONFIGFS_USET_DIR) {
1546 configfs_detach_group(item);
1548 mutex_lock(&subsys->su_mutex);
1549 client_disconnect_notify(parent_item, item);
1550 unlink_group(to_config_group(item));
1552 configfs_detach_item(item);
1554 mutex_lock(&subsys->su_mutex);
1555 client_disconnect_notify(parent_item, item);
1559 client_drop_item(parent_item, item);
1560 mutex_unlock(&subsys->su_mutex);
1562 /* Drop our reference from above */
1563 config_item_put(item);
1565 module_put(dead_item_owner);
1566 module_put(subsys_owner);
1571 const struct inode_operations configfs_dir_inode_operations = {
1572 .mkdir = configfs_mkdir,
1573 .rmdir = configfs_rmdir,
1574 .symlink = configfs_symlink,
1575 .unlink = configfs_unlink,
1576 .lookup = configfs_lookup,
1577 .setattr = configfs_setattr,
1580 const struct inode_operations configfs_root_inode_operations = {
1581 .lookup = configfs_lookup,
1582 .setattr = configfs_setattr,
1585 static int configfs_dir_open(struct inode *inode, struct file *file)
1587 struct dentry * dentry = file->f_path.dentry;
1588 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1591 inode_lock(d_inode(dentry));
1593 * Fake invisibility if dir belongs to a group/default groups hierarchy
1597 if (configfs_dirent_is_ready(parent_sd)) {
1598 file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);
1599 if (IS_ERR(file->private_data))
1600 err = PTR_ERR(file->private_data);
1604 inode_unlock(d_inode(dentry));
1609 static int configfs_dir_close(struct inode *inode, struct file *file)
1611 struct dentry * dentry = file->f_path.dentry;
1612 struct configfs_dirent * cursor = file->private_data;
1614 inode_lock(d_inode(dentry));
1615 spin_lock(&configfs_dirent_lock);
1616 list_del_init(&cursor->s_sibling);
1617 spin_unlock(&configfs_dirent_lock);
1618 inode_unlock(d_inode(dentry));
1620 release_configfs_dirent(cursor);
1625 /* Relationship between s_mode and the DT_xxx types */
1626 static inline unsigned char dt_type(struct configfs_dirent *sd)
1628 return (sd->s_mode >> 12) & 15;
1631 static int configfs_readdir(struct file *file, struct dir_context *ctx)
1633 struct dentry *dentry = file->f_path.dentry;
1634 struct super_block *sb = dentry->d_sb;
1635 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1636 struct configfs_dirent *cursor = file->private_data;
1637 struct list_head *p, *q = &cursor->s_sibling;
1640 if (!dir_emit_dots(file, ctx))
1642 spin_lock(&configfs_dirent_lock);
1644 list_move(q, &parent_sd->s_children);
1645 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1646 struct configfs_dirent *next;
1649 struct inode *inode = NULL;
1651 next = list_entry(p, struct configfs_dirent, s_sibling);
1652 if (!next->s_element)
1656 * We'll have a dentry and an inode for
1657 * PINNED items and for open attribute
1658 * files. We lock here to prevent a race
1659 * with configfs_d_iput() clearing
1660 * s_dentry before calling iput().
1662 * Why do we go to the trouble? If
1663 * someone has an attribute file open,
1664 * the inode number should match until
1665 * they close it. Beyond that, we don't
1668 dentry = next->s_dentry;
1670 inode = d_inode(dentry);
1673 spin_unlock(&configfs_dirent_lock);
1675 ino = iunique(sb, 2);
1677 name = configfs_get_name(next);
1680 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1683 spin_lock(&configfs_dirent_lock);
1688 spin_unlock(&configfs_dirent_lock);
1692 static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1694 struct dentry * dentry = file->f_path.dentry;
1698 offset += file->f_pos;
1707 if (offset != file->f_pos) {
1708 file->f_pos = offset;
1709 if (file->f_pos >= 2) {
1710 struct configfs_dirent *sd = dentry->d_fsdata;
1711 struct configfs_dirent *cursor = file->private_data;
1712 struct list_head *p;
1713 loff_t n = file->f_pos - 2;
1715 spin_lock(&configfs_dirent_lock);
1716 list_del(&cursor->s_sibling);
1717 p = sd->s_children.next;
1718 while (n && p != &sd->s_children) {
1719 struct configfs_dirent *next;
1720 next = list_entry(p, struct configfs_dirent,
1722 if (next->s_element)
1726 list_add_tail(&cursor->s_sibling, p);
1727 spin_unlock(&configfs_dirent_lock);
1733 const struct file_operations configfs_dir_operations = {
1734 .open = configfs_dir_open,
1735 .release = configfs_dir_close,
1736 .llseek = configfs_dir_lseek,
1737 .read = generic_read_dir,
1738 .iterate_shared = configfs_readdir,
1742 * configfs_register_group - creates a parent-child relation between two groups
1743 * @parent_group: parent group
1744 * @group: child group
1746 * link groups, creates dentry for the child and attaches it to the
1749 * Return: 0 on success, negative errno code on error
1751 int configfs_register_group(struct config_group *parent_group,
1752 struct config_group *group)
1754 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1755 struct dentry *parent;
1756 struct configfs_fragment *frag;
1759 frag = new_fragment();
1763 mutex_lock(&subsys->su_mutex);
1764 link_group(parent_group, group);
1765 mutex_unlock(&subsys->su_mutex);
1767 parent = parent_group->cg_item.ci_dentry;
1769 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1770 ret = create_default_group(parent_group, group, frag);
1774 spin_lock(&configfs_dirent_lock);
1775 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1776 spin_unlock(&configfs_dirent_lock);
1777 inode_unlock(d_inode(parent));
1781 inode_unlock(d_inode(parent));
1782 mutex_lock(&subsys->su_mutex);
1783 unlink_group(group);
1784 mutex_unlock(&subsys->su_mutex);
1788 EXPORT_SYMBOL(configfs_register_group);
1791 * configfs_unregister_group() - unregisters a child group from its parent
1792 * @group: parent group to be unregistered
1794 * Undoes configfs_register_group()
1796 void configfs_unregister_group(struct config_group *group)
1798 struct configfs_subsystem *subsys = group->cg_subsys;
1799 struct dentry *dentry = group->cg_item.ci_dentry;
1800 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1801 struct configfs_dirent *sd = dentry->d_fsdata;
1802 struct configfs_fragment *frag = sd->s_frag;
1804 down_write(&frag->frag_sem);
1805 frag->frag_dead = true;
1806 up_write(&frag->frag_sem);
1808 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1809 spin_lock(&configfs_dirent_lock);
1810 configfs_detach_prep(dentry, NULL);
1811 spin_unlock(&configfs_dirent_lock);
1813 configfs_detach_group(&group->cg_item);
1814 d_inode(dentry)->i_flags |= S_DEAD;
1817 fsnotify_rmdir(d_inode(parent), dentry);
1818 inode_unlock(d_inode(parent));
1822 mutex_lock(&subsys->su_mutex);
1823 unlink_group(group);
1824 mutex_unlock(&subsys->su_mutex);
1826 EXPORT_SYMBOL(configfs_unregister_group);
1829 * configfs_register_default_group() - allocates and registers a child group
1830 * @parent_group: parent group
1831 * @name: child group name
1832 * @item_type: child item type description
1834 * boilerplate to allocate and register a child group with its parent. We need
1835 * kzalloc'ed memory because child's default_group is initially empty.
1837 * Return: allocated config group or ERR_PTR() on error
1839 struct config_group *
1840 configfs_register_default_group(struct config_group *parent_group,
1842 const struct config_item_type *item_type)
1845 struct config_group *group;
1847 group = kzalloc(sizeof(*group), GFP_KERNEL);
1849 return ERR_PTR(-ENOMEM);
1850 config_group_init_type_name(group, name, item_type);
1852 ret = configfs_register_group(parent_group, group);
1855 return ERR_PTR(ret);
1859 EXPORT_SYMBOL(configfs_register_default_group);
1862 * configfs_unregister_default_group() - unregisters and frees a child group
1863 * @group: the group to act on
1865 void configfs_unregister_default_group(struct config_group *group)
1867 configfs_unregister_group(group);
1870 EXPORT_SYMBOL(configfs_unregister_default_group);
1872 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1875 struct config_group *group = &subsys->su_group;
1876 struct dentry *dentry;
1877 struct dentry *root;
1878 struct configfs_dirent *sd;
1879 struct configfs_fragment *frag;
1881 frag = new_fragment();
1885 root = configfs_pin_fs();
1888 return PTR_ERR(root);
1891 if (!group->cg_item.ci_name)
1892 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1894 sd = root->d_fsdata;
1895 mutex_lock(&configfs_subsystem_mutex);
1896 link_group(to_config_group(sd->s_element), group);
1897 mutex_unlock(&configfs_subsystem_mutex);
1899 inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
1902 dentry = d_alloc_name(root, group->cg_item.ci_name);
1904 d_add(dentry, NULL);
1906 err = configfs_attach_group(sd->s_element, &group->cg_item,
1909 BUG_ON(d_inode(dentry));
1913 spin_lock(&configfs_dirent_lock);
1914 configfs_dir_set_ready(dentry->d_fsdata);
1915 spin_unlock(&configfs_dirent_lock);
1919 inode_unlock(d_inode(root));
1922 mutex_lock(&configfs_subsystem_mutex);
1923 unlink_group(group);
1924 mutex_unlock(&configfs_subsystem_mutex);
1925 configfs_release_fs();
1932 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1934 struct config_group *group = &subsys->su_group;
1935 struct dentry *dentry = group->cg_item.ci_dentry;
1936 struct dentry *root = dentry->d_sb->s_root;
1937 struct configfs_dirent *sd = dentry->d_fsdata;
1938 struct configfs_fragment *frag = sd->s_frag;
1940 if (dentry->d_parent != root) {
1941 pr_err("Tried to unregister non-subsystem!\n");
1945 down_write(&frag->frag_sem);
1946 frag->frag_dead = true;
1947 up_write(&frag->frag_sem);
1949 inode_lock_nested(d_inode(root),
1951 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
1952 mutex_lock(&configfs_symlink_mutex);
1953 spin_lock(&configfs_dirent_lock);
1954 if (configfs_detach_prep(dentry, NULL)) {
1955 pr_err("Tried to unregister non-empty subsystem!\n");
1957 spin_unlock(&configfs_dirent_lock);
1958 mutex_unlock(&configfs_symlink_mutex);
1959 configfs_detach_group(&group->cg_item);
1960 d_inode(dentry)->i_flags |= S_DEAD;
1962 inode_unlock(d_inode(dentry));
1965 fsnotify_rmdir(d_inode(root), dentry);
1967 inode_unlock(d_inode(root));
1971 mutex_lock(&configfs_subsystem_mutex);
1972 unlink_group(group);
1973 mutex_unlock(&configfs_subsystem_mutex);
1974 configfs_release_fs();
1977 EXPORT_SYMBOL(configfs_register_subsystem);
1978 EXPORT_SYMBOL(configfs_unregister_subsystem);