1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * dir.c - Operations for configfs directories.
6 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
8 * configfs Copyright (C) 2005 Oracle. All rights reserved.
14 #include <linux/fsnotify.h>
15 #include <linux/mount.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/err.h>
20 #include <linux/configfs.h>
21 #include "configfs_internal.h"
24 * Protects mutations of configfs_dirent linkage together with proper i_mutex
25 * Also protects mutations of symlinks linkage to target configfs_dirent
26 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
27 * and configfs_dirent_lock locked, in that order.
28 * This allows one to safely traverse configfs_dirent trees and symlinks without
29 * having to lock inodes.
31 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
32 * unlocked is not reliable unless in detach_groups() called from
33 * rmdir()/unregister() and from configfs_attach_group()
35 DEFINE_SPINLOCK(configfs_dirent_lock);
37 static void configfs_d_iput(struct dentry * dentry,
40 struct configfs_dirent *sd = dentry->d_fsdata;
43 /* Coordinate with configfs_readdir */
44 spin_lock(&configfs_dirent_lock);
46 * Set sd->s_dentry to null only when this dentry is the one
47 * that is going to be killed. Otherwise configfs_d_iput may
48 * run just after configfs_attach_attr and set sd->s_dentry to
49 * NULL even it's still in use.
51 if (sd->s_dentry == dentry)
54 spin_unlock(&configfs_dirent_lock);
60 const struct dentry_operations configfs_dentry_ops = {
61 .d_iput = configfs_d_iput,
62 .d_delete = always_delete_dentry,
68 * Helpers to make lockdep happy with our recursive locking of default groups'
69 * inodes (see configfs_attach_group() and configfs_detach_group()).
70 * We put default groups i_mutexes in separate classes according to their depth
71 * from the youngest non-default group ancestor.
73 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
74 * groups A/B and A/C will have their inode's mutex in class
75 * default_group_class[0], and default group A/C/D will be in
76 * default_group_class[1].
78 * The lock classes are declared and assigned in inode.c, according to the
80 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
81 * default groups, and reset to -1 when all default groups are attached. During
82 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
83 * inode's mutex is set to default_group_class[s_depth - 1].
86 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
91 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
92 struct configfs_dirent *sd)
94 int parent_depth = parent_sd->s_depth;
96 if (parent_depth >= 0)
97 sd->s_depth = parent_depth + 1;
101 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
104 * item's i_mutex class is already setup, so s_depth is now only
105 * used to set new sub-directories s_depth, which is always done
106 * with item's i_mutex locked.
109 * sd->s_depth == -1 iff we are a non default group.
110 * else (we are a default group) sd->s_depth > 0 (see
113 if (sd->s_depth == -1)
115 * We are a non default group and we are going to create
122 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
124 /* We will not create default groups anymore. */
128 #else /* CONFIG_LOCKDEP */
130 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
134 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
135 struct configfs_dirent *sd)
140 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
145 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
149 #endif /* CONFIG_LOCKDEP */
151 static struct configfs_fragment *new_fragment(void)
153 struct configfs_fragment *p;
155 p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL);
157 atomic_set(&p->frag_count, 1);
158 init_rwsem(&p->frag_sem);
159 p->frag_dead = false;
164 void put_fragment(struct configfs_fragment *frag)
166 if (frag && atomic_dec_and_test(&frag->frag_count))
170 struct configfs_fragment *get_fragment(struct configfs_fragment *frag)
173 atomic_inc(&frag->frag_count);
178 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
180 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
181 void *element, int type,
182 struct configfs_fragment *frag)
184 struct configfs_dirent * sd;
186 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
188 return ERR_PTR(-ENOMEM);
190 atomic_set(&sd->s_count, 1);
191 INIT_LIST_HEAD(&sd->s_children);
192 sd->s_element = element;
194 configfs_init_dirent_depth(sd);
195 spin_lock(&configfs_dirent_lock);
196 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
197 spin_unlock(&configfs_dirent_lock);
198 kmem_cache_free(configfs_dir_cachep, sd);
199 return ERR_PTR(-ENOENT);
201 sd->s_frag = get_fragment(frag);
202 list_add(&sd->s_sibling, &parent_sd->s_children);
203 spin_unlock(&configfs_dirent_lock);
210 * Return -EEXIST if there is already a configfs element with the same
211 * name for the same parent.
213 * called with parent inode's i_mutex held
215 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
216 const unsigned char *new)
218 struct configfs_dirent * sd;
220 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
222 const unsigned char *existing = configfs_get_name(sd);
223 if (strcmp(existing, new))
234 int configfs_make_dirent(struct configfs_dirent * parent_sd,
235 struct dentry * dentry, void * element,
236 umode_t mode, int type, struct configfs_fragment *frag)
238 struct configfs_dirent * sd;
240 sd = configfs_new_dirent(parent_sd, element, type, frag);
245 sd->s_dentry = dentry;
247 dentry->d_fsdata = configfs_get(sd);
252 static void configfs_remove_dirent(struct dentry *dentry)
254 struct configfs_dirent *sd = dentry->d_fsdata;
258 spin_lock(&configfs_dirent_lock);
259 list_del_init(&sd->s_sibling);
260 spin_unlock(&configfs_dirent_lock);
265 * configfs_create_dir - create a directory for an config_item.
266 * @item: config_itemwe're creating directory for.
267 * @dentry: config_item's dentry.
268 * @frag: config_item's fragment.
270 * Note: user-created entries won't be allowed under this new directory
271 * until it is validated by configfs_dir_set_ready()
274 static int configfs_create_dir(struct config_item *item, struct dentry *dentry,
275 struct configfs_fragment *frag)
278 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
279 struct dentry *p = dentry->d_parent;
284 error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
288 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
289 CONFIGFS_DIR | CONFIGFS_USET_CREATING,
294 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
295 inode = configfs_create(dentry, mode);
299 inode->i_op = &configfs_dir_inode_operations;
300 inode->i_fop = &configfs_dir_operations;
301 /* directory inodes start off with i_nlink == 2 (for "." entry) */
303 d_instantiate(dentry, inode);
305 dget(dentry); /* pin directory dentries in core */
306 inc_nlink(d_inode(p));
307 item->ci_dentry = dentry;
311 configfs_remove_dirent(dentry);
312 return PTR_ERR(inode);
316 * Allow userspace to create new entries under a new directory created with
317 * configfs_create_dir(), and under all of its chidlren directories recursively.
318 * @sd configfs_dirent of the new directory to validate
320 * Caller must hold configfs_dirent_lock.
322 static void configfs_dir_set_ready(struct configfs_dirent *sd)
324 struct configfs_dirent *child_sd;
326 sd->s_type &= ~CONFIGFS_USET_CREATING;
327 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
328 if (child_sd->s_type & CONFIGFS_USET_CREATING)
329 configfs_dir_set_ready(child_sd);
333 * Check that a directory does not belong to a directory hierarchy being
334 * attached and not validated yet.
335 * @sd configfs_dirent of the directory to check
337 * @return non-zero iff the directory was validated
339 * Note: takes configfs_dirent_lock, so the result may change from false to true
340 * in two consecutive calls, but never from true to false.
342 int configfs_dirent_is_ready(struct configfs_dirent *sd)
346 spin_lock(&configfs_dirent_lock);
347 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
348 spin_unlock(&configfs_dirent_lock);
353 int configfs_create_link(struct configfs_dirent *target, struct dentry *parent,
354 struct dentry *dentry, char *body)
357 umode_t mode = S_IFLNK | S_IRWXUGO;
358 struct configfs_dirent *p = parent->d_fsdata;
361 err = configfs_make_dirent(p, dentry, target, mode, CONFIGFS_ITEM_LINK,
366 inode = configfs_create(dentry, mode);
370 inode->i_link = body;
371 inode->i_op = &configfs_symlink_inode_operations;
372 d_instantiate(dentry, inode);
373 dget(dentry); /* pin link dentries in core */
377 configfs_remove_dirent(dentry);
378 return PTR_ERR(inode);
381 static void remove_dir(struct dentry * d)
383 struct dentry * parent = dget(d->d_parent);
385 configfs_remove_dirent(d);
387 if (d_really_is_positive(d))
388 simple_rmdir(d_inode(parent),d);
390 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
396 * configfs_remove_dir - remove an config_item's directory.
397 * @item: config_item we're removing.
399 * The only thing special about this is that we remove any files in
400 * the directory before we remove the directory, and we've inlined
401 * what used to be configfs_rmdir() below, instead of calling separately.
403 * Caller holds the mutex of the item's inode
406 static void configfs_remove_dir(struct config_item * item)
408 struct dentry * dentry = dget(item->ci_dentry);
415 * Drop reference from dget() on entrance.
421 /* attaches attribute's configfs_dirent to the dentry corresponding to the
424 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
426 struct configfs_attribute * attr = sd->s_element;
429 spin_lock(&configfs_dirent_lock);
430 dentry->d_fsdata = configfs_get(sd);
431 sd->s_dentry = dentry;
432 spin_unlock(&configfs_dirent_lock);
434 inode = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG);
437 return PTR_ERR(inode);
439 if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) {
441 inode->i_fop = &configfs_bin_file_operations;
443 inode->i_size = PAGE_SIZE;
444 inode->i_fop = &configfs_file_operations;
446 d_add(dentry, inode);
450 static struct dentry * configfs_lookup(struct inode *dir,
451 struct dentry *dentry,
454 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
455 struct configfs_dirent * sd;
460 * Fake invisibility if dir belongs to a group/default groups hierarchy
463 * This forbids userspace to read/write attributes of items which may
464 * not complete their initialization, since the dentries of the
465 * attributes won't be instantiated.
468 if (!configfs_dirent_is_ready(parent_sd))
471 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
472 if (sd->s_type & CONFIGFS_NOT_PINNED) {
473 const unsigned char * name = configfs_get_name(sd);
475 if (strcmp(name, dentry->d_name.name))
479 err = configfs_attach_attr(sd, dentry);
486 * If it doesn't exist and it isn't a NOT_PINNED item,
487 * it must be negative.
489 if (dentry->d_name.len > NAME_MAX)
490 return ERR_PTR(-ENAMETOOLONG);
500 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
501 * attributes and are removed by rmdir(). We recurse, setting
502 * CONFIGFS_USET_DROPPING on all children that are candidates for
504 * If there is an error, the caller will reset the flags via
505 * configfs_detach_rollback().
507 static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait)
509 struct configfs_dirent *parent_sd = dentry->d_fsdata;
510 struct configfs_dirent *sd;
513 /* Mark that we're trying to drop the group */
514 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
517 if (parent_sd->s_links)
521 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
522 if (!sd->s_element ||
523 (sd->s_type & CONFIGFS_NOT_PINNED))
525 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
526 /* Abort if racing with mkdir() */
527 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
529 *wait= dget(sd->s_dentry);
534 * Yup, recursive. If there's a problem, blame
535 * deep nesting of default_groups
537 ret = configfs_detach_prep(sd->s_dentry, wait);
551 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
554 static void configfs_detach_rollback(struct dentry *dentry)
556 struct configfs_dirent *parent_sd = dentry->d_fsdata;
557 struct configfs_dirent *sd;
559 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
561 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
562 if (sd->s_type & CONFIGFS_USET_DEFAULT)
563 configfs_detach_rollback(sd->s_dentry);
566 static void detach_attrs(struct config_item * item)
568 struct dentry * dentry = dget(item->ci_dentry);
569 struct configfs_dirent * parent_sd;
570 struct configfs_dirent * sd, * tmp;
575 pr_debug("configfs %s: dropping attrs for dir\n",
576 dentry->d_name.name);
578 parent_sd = dentry->d_fsdata;
579 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
580 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
582 spin_lock(&configfs_dirent_lock);
583 list_del_init(&sd->s_sibling);
584 spin_unlock(&configfs_dirent_lock);
585 configfs_drop_dentry(sd, dentry);
590 * Drop reference from dget() on entrance.
595 static int populate_attrs(struct config_item *item)
597 const struct config_item_type *t = item->ci_type;
598 struct configfs_attribute *attr;
599 struct configfs_bin_attribute *bin_attr;
606 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
607 if ((error = configfs_create_file(item, attr)))
611 if (t->ct_bin_attrs) {
612 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
613 error = configfs_create_bin_file(item, bin_attr);
625 static int configfs_attach_group(struct config_item *parent_item,
626 struct config_item *item,
627 struct dentry *dentry,
628 struct configfs_fragment *frag);
629 static void configfs_detach_group(struct config_item *item);
631 static void detach_groups(struct config_group *group)
633 struct dentry * dentry = dget(group->cg_item.ci_dentry);
634 struct dentry *child;
635 struct configfs_dirent *parent_sd;
636 struct configfs_dirent *sd, *tmp;
641 parent_sd = dentry->d_fsdata;
642 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
643 if (!sd->s_element ||
644 !(sd->s_type & CONFIGFS_USET_DEFAULT))
647 child = sd->s_dentry;
649 inode_lock(d_inode(child));
651 configfs_detach_group(sd->s_element);
652 d_inode(child)->i_flags |= S_DEAD;
655 inode_unlock(d_inode(child));
662 * Drop reference from dget() on entrance.
668 * This fakes mkdir(2) on a default_groups[] entry. It
669 * creates a dentry, attachs it, and then does fixup
672 * We could, perhaps, tweak our parent's ->mkdir for a minute and
673 * try using vfs_mkdir. Just a thought.
675 static int create_default_group(struct config_group *parent_group,
676 struct config_group *group,
677 struct configfs_fragment *frag)
680 struct configfs_dirent *sd;
681 /* We trust the caller holds a reference to parent */
682 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
684 if (!group->cg_item.ci_name)
685 group->cg_item.ci_name = group->cg_item.ci_namebuf;
688 child = d_alloc_name(parent, group->cg_item.ci_name);
692 ret = configfs_attach_group(&parent_group->cg_item,
693 &group->cg_item, child, frag);
695 sd = child->d_fsdata;
696 sd->s_type |= CONFIGFS_USET_DEFAULT;
698 BUG_ON(d_inode(child));
707 static int populate_groups(struct config_group *group,
708 struct configfs_fragment *frag)
710 struct config_group *new_group;
713 list_for_each_entry(new_group, &group->default_groups, group_entry) {
714 ret = create_default_group(group, new_group, frag);
716 detach_groups(group);
724 void configfs_remove_default_groups(struct config_group *group)
726 struct config_group *g, *n;
728 list_for_each_entry_safe(g, n, &group->default_groups, group_entry) {
729 list_del(&g->group_entry);
730 config_item_put(&g->cg_item);
733 EXPORT_SYMBOL(configfs_remove_default_groups);
736 * All of link_obj/unlink_obj/link_group/unlink_group require that
737 * subsys->su_mutex is held.
740 static void unlink_obj(struct config_item *item)
742 struct config_group *group;
744 group = item->ci_group;
746 list_del_init(&item->ci_entry);
748 item->ci_group = NULL;
749 item->ci_parent = NULL;
751 /* Drop the reference for ci_entry */
752 config_item_put(item);
754 /* Drop the reference for ci_parent */
755 config_group_put(group);
759 static void link_obj(struct config_item *parent_item, struct config_item *item)
762 * Parent seems redundant with group, but it makes certain
763 * traversals much nicer.
765 item->ci_parent = parent_item;
768 * We hold a reference on the parent for the child's ci_parent
771 item->ci_group = config_group_get(to_config_group(parent_item));
772 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
775 * We hold a reference on the child for ci_entry on the parent's
778 config_item_get(item);
781 static void unlink_group(struct config_group *group)
783 struct config_group *new_group;
785 list_for_each_entry(new_group, &group->default_groups, group_entry)
786 unlink_group(new_group);
788 group->cg_subsys = NULL;
789 unlink_obj(&group->cg_item);
792 static void link_group(struct config_group *parent_group, struct config_group *group)
794 struct config_group *new_group;
795 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
797 link_obj(&parent_group->cg_item, &group->cg_item);
799 if (parent_group->cg_subsys)
800 subsys = parent_group->cg_subsys;
801 else if (configfs_is_root(&parent_group->cg_item))
802 subsys = to_configfs_subsystem(group);
805 group->cg_subsys = subsys;
807 list_for_each_entry(new_group, &group->default_groups, group_entry)
808 link_group(group, new_group);
812 * The goal is that configfs_attach_item() (and
813 * configfs_attach_group()) can be called from either the VFS or this
814 * module. That is, they assume that the items have been created,
815 * the dentry allocated, and the dcache is all ready to go.
817 * If they fail, they must clean up after themselves as if they
818 * had never been called. The caller (VFS or local function) will
819 * handle cleaning up the dcache bits.
821 * configfs_detach_group() and configfs_detach_item() behave similarly on
822 * the way out. They assume that the proper semaphores are held, they
823 * clean up the configfs items, and they expect their callers will
824 * handle the dcache bits.
826 static int configfs_attach_item(struct config_item *parent_item,
827 struct config_item *item,
828 struct dentry *dentry,
829 struct configfs_fragment *frag)
833 ret = configfs_create_dir(item, dentry, frag);
835 ret = populate_attrs(item);
838 * We are going to remove an inode and its dentry but
839 * the VFS may already have hit and used them. Thus,
840 * we must lock them as rmdir() would.
842 inode_lock(d_inode(dentry));
843 configfs_remove_dir(item);
844 d_inode(dentry)->i_flags |= S_DEAD;
846 inode_unlock(d_inode(dentry));
854 /* Caller holds the mutex of the item's inode */
855 static void configfs_detach_item(struct config_item *item)
858 configfs_remove_dir(item);
861 static int configfs_attach_group(struct config_item *parent_item,
862 struct config_item *item,
863 struct dentry *dentry,
864 struct configfs_fragment *frag)
867 struct configfs_dirent *sd;
869 ret = configfs_attach_item(parent_item, item, dentry, frag);
871 sd = dentry->d_fsdata;
872 sd->s_type |= CONFIGFS_USET_DIR;
875 * FYI, we're faking mkdir in populate_groups()
876 * We must lock the group's inode to avoid races with the VFS
877 * which can already hit the inode and try to add/remove entries
880 * We must also lock the inode to remove it safely in case of
881 * error, as rmdir() would.
883 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
884 configfs_adjust_dir_dirent_depth_before_populate(sd);
885 ret = populate_groups(to_config_group(item), frag);
887 configfs_detach_item(item);
888 d_inode(dentry)->i_flags |= S_DEAD;
891 configfs_adjust_dir_dirent_depth_after_populate(sd);
892 inode_unlock(d_inode(dentry));
900 /* Caller holds the mutex of the group's inode */
901 static void configfs_detach_group(struct config_item *item)
903 detach_groups(to_config_group(item));
904 configfs_detach_item(item);
908 * After the item has been detached from the filesystem view, we are
909 * ready to tear it out of the hierarchy. Notify the client before
910 * we do that so they can perform any cleanup that requires
911 * navigating the hierarchy. A client does not need to provide this
912 * callback. The subsystem semaphore MUST be held by the caller, and
913 * references must be valid for both items. It also assumes the
914 * caller has validated ci_type.
916 static void client_disconnect_notify(struct config_item *parent_item,
917 struct config_item *item)
919 const struct config_item_type *type;
921 type = parent_item->ci_type;
924 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
925 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
930 * Drop the initial reference from make_item()/make_group()
931 * This function assumes that reference is held on item
932 * and that item holds a valid reference to the parent. Also, it
933 * assumes the caller has validated ci_type.
935 static void client_drop_item(struct config_item *parent_item,
936 struct config_item *item)
938 const struct config_item_type *type;
940 type = parent_item->ci_type;
944 * If ->drop_item() exists, it is responsible for the
947 if (type->ct_group_ops && type->ct_group_ops->drop_item)
948 type->ct_group_ops->drop_item(to_config_group(parent_item),
951 config_item_put(item);
955 static void configfs_dump_one(struct configfs_dirent *sd, int level)
957 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
959 #define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type);
960 type_print(CONFIGFS_ROOT);
961 type_print(CONFIGFS_DIR);
962 type_print(CONFIGFS_ITEM_ATTR);
963 type_print(CONFIGFS_ITEM_LINK);
964 type_print(CONFIGFS_USET_DIR);
965 type_print(CONFIGFS_USET_DEFAULT);
966 type_print(CONFIGFS_USET_DROPPING);
970 static int configfs_dump(struct configfs_dirent *sd, int level)
972 struct configfs_dirent *child_sd;
975 configfs_dump_one(sd, level);
977 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
980 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
981 ret = configfs_dump(child_sd, level + 2);
992 * configfs_depend_item() and configfs_undepend_item()
994 * WARNING: Do not call these from a configfs callback!
996 * This describes these functions and their helpers.
998 * Allow another kernel system to depend on a config_item. If this
999 * happens, the item cannot go away until the dependent can live without
1000 * it. The idea is to give client modules as simple an interface as
1001 * possible. When a system asks them to depend on an item, they just
1002 * call configfs_depend_item(). If the item is live and the client
1003 * driver is in good shape, we'll happily do the work for them.
1005 * Why is the locking complex? Because configfs uses the VFS to handle
1006 * all locking, but this function is called outside the normal
1007 * VFS->configfs path. So it must take VFS locks to prevent the
1008 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1009 * why you can't call these functions underneath configfs callbacks.
1011 * Note, btw, that this can be called at *any* time, even when a configfs
1012 * subsystem isn't registered, or when configfs is loading or unloading.
1013 * Just like configfs_register_subsystem(). So we take the same
1014 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1015 * If we can find the target item in the
1016 * configfs tree, it must be part of the subsystem tree as well, so we
1017 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1018 * locking out mkdir() and rmdir(), who might be racing us.
1022 * configfs_depend_prep()
1024 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1025 * attributes. This is similar but not the same to configfs_detach_prep().
1026 * Note that configfs_detach_prep() expects the parent to be locked when it
1027 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1028 * do that so we can unlock it if we find nothing.
1030 * Here we do a depth-first search of the dentry hierarchy looking for
1032 * We deliberately ignore items tagged as dropping since they are virtually
1033 * dead, as well as items in the middle of attachment since they virtually
1034 * do not exist yet. This completes the locking out of racing mkdir() and
1036 * Note: subdirectories in the middle of attachment start with s_type =
1037 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1038 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1039 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1041 * If the target is not found, -ENOENT is bubbled up.
1043 * This adds a requirement that all config_items be unique!
1045 * This is recursive. There isn't
1046 * much on the stack, though, so folks that need this function - be careful
1047 * about your stack! Patches will be accepted to make it iterative.
1049 static int configfs_depend_prep(struct dentry *origin,
1050 struct config_item *target)
1052 struct configfs_dirent *child_sd, *sd;
1055 BUG_ON(!origin || !origin->d_fsdata);
1056 sd = origin->d_fsdata;
1058 if (sd->s_element == target) /* Boo-yah */
1061 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1062 if ((child_sd->s_type & CONFIGFS_DIR) &&
1063 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1064 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1065 ret = configfs_depend_prep(child_sd->s_dentry,
1068 goto out; /* Child path boo-yah */
1072 /* We looped all our children and didn't find target */
1079 static int configfs_do_depend_item(struct dentry *subsys_dentry,
1080 struct config_item *target)
1082 struct configfs_dirent *p;
1085 spin_lock(&configfs_dirent_lock);
1086 /* Scan the tree, return 0 if found */
1087 ret = configfs_depend_prep(subsys_dentry, target);
1089 goto out_unlock_dirent_lock;
1092 * We are sure that the item is not about to be removed by rmdir(), and
1093 * not in the middle of attachment by mkdir().
1095 p = target->ci_dentry->d_fsdata;
1096 p->s_dependent_count += 1;
1098 out_unlock_dirent_lock:
1099 spin_unlock(&configfs_dirent_lock);
1104 static inline struct configfs_dirent *
1105 configfs_find_subsys_dentry(struct configfs_dirent *root_sd,
1106 struct config_item *subsys_item)
1108 struct configfs_dirent *p;
1109 struct configfs_dirent *ret = NULL;
1111 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1112 if (p->s_type & CONFIGFS_DIR &&
1113 p->s_element == subsys_item) {
1123 int configfs_depend_item(struct configfs_subsystem *subsys,
1124 struct config_item *target)
1127 struct configfs_dirent *subsys_sd;
1128 struct config_item *s_item = &subsys->su_group.cg_item;
1129 struct dentry *root;
1132 * Pin the configfs filesystem. This means we can safely access
1133 * the root of the configfs filesystem.
1135 root = configfs_pin_fs();
1137 return PTR_ERR(root);
1140 * Next, lock the root directory. We're going to check that the
1141 * subsystem is really registered, and so we need to lock out
1142 * configfs_[un]register_subsystem().
1144 inode_lock(d_inode(root));
1146 subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item);
1152 /* Ok, now we can trust subsys/s_item */
1153 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1156 inode_unlock(d_inode(root));
1159 * If we succeeded, the fs is pinned via other methods. If not,
1160 * we're done with it anyway. So release_fs() is always right.
1162 configfs_release_fs();
1166 EXPORT_SYMBOL(configfs_depend_item);
1169 * Release the dependent linkage. This is much simpler than
1170 * configfs_depend_item() because we know that the client driver is
1171 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1173 void configfs_undepend_item(struct config_item *target)
1175 struct configfs_dirent *sd;
1178 * Since we can trust everything is pinned, we just need
1179 * configfs_dirent_lock.
1181 spin_lock(&configfs_dirent_lock);
1183 sd = target->ci_dentry->d_fsdata;
1184 BUG_ON(sd->s_dependent_count < 1);
1186 sd->s_dependent_count -= 1;
1189 * After this unlock, we cannot trust the item to stay alive!
1190 * DO NOT REFERENCE item after this unlock.
1192 spin_unlock(&configfs_dirent_lock);
1194 EXPORT_SYMBOL(configfs_undepend_item);
1197 * caller_subsys is a caller's subsystem not target's. This is used to
1198 * determine if we should lock root and check subsys or not. When we are
1199 * in the same subsystem as our target there is no need to do locking as
1200 * we know that subsys is valid and is not unregistered during this function
1201 * as we are called from callback of one of his children and VFS holds a lock
1202 * on some inode. Otherwise we have to lock our root to ensure that target's
1203 * subsystem it is not unregistered during this function.
1205 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
1206 struct config_item *target)
1208 struct configfs_subsystem *target_subsys;
1209 struct config_group *root, *parent;
1210 struct configfs_dirent *subsys_sd;
1213 /* Disallow this function for configfs root */
1214 if (configfs_is_root(target))
1217 parent = target->ci_group;
1219 * This may happen when someone is trying to depend root
1220 * directory of some subsystem
1222 if (configfs_is_root(&parent->cg_item)) {
1223 target_subsys = to_configfs_subsystem(to_config_group(target));
1226 target_subsys = parent->cg_subsys;
1227 /* Find a cofnigfs root as we may need it for locking */
1228 for (root = parent; !configfs_is_root(&root->cg_item);
1229 root = root->cg_item.ci_group)
1233 if (target_subsys != caller_subsys) {
1235 * We are in other configfs subsystem, so we have to do
1236 * additional locking to prevent other subsystem from being
1239 inode_lock(d_inode(root->cg_item.ci_dentry));
1242 * As we are trying to depend item from other subsystem
1243 * we have to check if this subsystem is still registered
1245 subsys_sd = configfs_find_subsys_dentry(
1246 root->cg_item.ci_dentry->d_fsdata,
1247 &target_subsys->su_group.cg_item);
1249 goto out_root_unlock;
1251 subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata;
1254 /* Now we can execute core of depend item */
1255 ret = configfs_do_depend_item(subsys_sd->s_dentry, target);
1257 if (target_subsys != caller_subsys)
1260 * We were called from subsystem other than our target so we
1261 * took some locks so now it's time to release them
1263 inode_unlock(d_inode(root->cg_item.ci_dentry));
1267 EXPORT_SYMBOL(configfs_depend_item_unlocked);
1269 static int configfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
1270 struct dentry *dentry, umode_t mode)
1274 struct config_group *group = NULL;
1275 struct config_item *item = NULL;
1276 struct config_item *parent_item;
1277 struct configfs_subsystem *subsys;
1278 struct configfs_dirent *sd;
1279 const struct config_item_type *type;
1280 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1281 struct configfs_fragment *frag;
1284 sd = dentry->d_parent->d_fsdata;
1287 * Fake invisibility if dir belongs to a group/default groups hierarchy
1290 if (!configfs_dirent_is_ready(sd)) {
1295 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1300 frag = new_fragment();
1306 /* Get a working ref for the duration of this function */
1307 parent_item = configfs_get_config_item(dentry->d_parent);
1308 type = parent_item->ci_type;
1309 subsys = to_config_group(parent_item)->cg_subsys;
1312 if (!type || !type->ct_group_ops ||
1313 (!type->ct_group_ops->make_group &&
1314 !type->ct_group_ops->make_item)) {
1315 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1320 * The subsystem may belong to a different module than the item
1321 * being created. We don't want to safely pin the new item but
1322 * fail to pin the subsystem it sits under.
1324 if (!subsys->su_group.cg_item.ci_type) {
1328 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1329 if (!try_module_get(subsys_owner)) {
1334 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1337 goto out_subsys_put;
1340 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1342 mutex_lock(&subsys->su_mutex);
1343 if (type->ct_group_ops->make_group) {
1344 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1346 group = ERR_PTR(-ENOMEM);
1347 if (!IS_ERR(group)) {
1348 link_group(to_config_group(parent_item), group);
1349 item = &group->cg_item;
1351 ret = PTR_ERR(group);
1353 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1355 item = ERR_PTR(-ENOMEM);
1357 link_obj(parent_item, item);
1359 ret = PTR_ERR(item);
1361 mutex_unlock(&subsys->su_mutex);
1366 * If ret != 0, then link_obj() was never called.
1367 * There are no extra references to clean up.
1369 goto out_subsys_put;
1373 * link_obj() has been called (via link_group() for groups).
1374 * From here on out, errors must clean that up.
1377 type = item->ci_type;
1383 new_item_owner = type->ct_owner;
1384 if (!try_module_get(new_item_owner)) {
1390 * I hate doing it this way, but if there is
1391 * an error, module_put() probably should
1392 * happen after any cleanup.
1397 * Make racing rmdir() fail if it did not tag parent with
1398 * CONFIGFS_USET_DROPPING
1399 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1400 * fail and let rmdir() terminate correctly
1402 spin_lock(&configfs_dirent_lock);
1403 /* This will make configfs_detach_prep() fail */
1404 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1405 spin_unlock(&configfs_dirent_lock);
1408 ret = configfs_attach_group(parent_item, item, dentry, frag);
1410 ret = configfs_attach_item(parent_item, item, dentry, frag);
1412 spin_lock(&configfs_dirent_lock);
1413 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1415 configfs_dir_set_ready(dentry->d_fsdata);
1416 spin_unlock(&configfs_dirent_lock);
1420 /* Tear down everything we built up */
1421 mutex_lock(&subsys->su_mutex);
1423 client_disconnect_notify(parent_item, item);
1425 unlink_group(group);
1428 client_drop_item(parent_item, item);
1430 mutex_unlock(&subsys->su_mutex);
1433 module_put(new_item_owner);
1438 module_put(subsys_owner);
1442 * link_obj()/link_group() took a reference from child->parent,
1443 * so the parent is safely pinned. We can drop our working
1446 config_item_put(parent_item);
1453 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1455 struct config_item *parent_item;
1456 struct config_item *item;
1457 struct configfs_subsystem *subsys;
1458 struct configfs_dirent *sd;
1459 struct configfs_fragment *frag;
1460 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1463 sd = dentry->d_fsdata;
1464 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1467 /* Get a working ref until we have the child */
1468 parent_item = configfs_get_config_item(dentry->d_parent);
1469 subsys = to_config_group(parent_item)->cg_subsys;
1472 if (!parent_item->ci_type) {
1473 config_item_put(parent_item);
1477 /* configfs_mkdir() shouldn't have allowed this */
1478 BUG_ON(!subsys->su_group.cg_item.ci_type);
1479 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1482 * Ensure that no racing symlink() will make detach_prep() fail while
1483 * the new link is temporarily attached
1486 struct dentry *wait;
1488 mutex_lock(&configfs_symlink_mutex);
1489 spin_lock(&configfs_dirent_lock);
1491 * Here's where we check for dependents. We're protected by
1492 * configfs_dirent_lock.
1493 * If no dependent, atomically tag the item as dropping.
1495 ret = sd->s_dependent_count ? -EBUSY : 0;
1497 ret = configfs_detach_prep(dentry, &wait);
1499 configfs_detach_rollback(dentry);
1501 spin_unlock(&configfs_dirent_lock);
1502 mutex_unlock(&configfs_symlink_mutex);
1505 if (ret != -EAGAIN) {
1506 config_item_put(parent_item);
1510 /* Wait until the racing operation terminates */
1511 inode_lock(d_inode(wait));
1512 inode_unlock(d_inode(wait));
1515 } while (ret == -EAGAIN);
1518 if (down_write_killable(&frag->frag_sem)) {
1519 spin_lock(&configfs_dirent_lock);
1520 configfs_detach_rollback(dentry);
1521 spin_unlock(&configfs_dirent_lock);
1522 config_item_put(parent_item);
1525 frag->frag_dead = true;
1526 up_write(&frag->frag_sem);
1528 /* Get a working ref for the duration of this function */
1529 item = configfs_get_config_item(dentry);
1531 /* Drop reference from above, item already holds one. */
1532 config_item_put(parent_item);
1535 dead_item_owner = item->ci_type->ct_owner;
1537 if (sd->s_type & CONFIGFS_USET_DIR) {
1538 configfs_detach_group(item);
1540 mutex_lock(&subsys->su_mutex);
1541 client_disconnect_notify(parent_item, item);
1542 unlink_group(to_config_group(item));
1544 configfs_detach_item(item);
1546 mutex_lock(&subsys->su_mutex);
1547 client_disconnect_notify(parent_item, item);
1551 client_drop_item(parent_item, item);
1552 mutex_unlock(&subsys->su_mutex);
1554 /* Drop our reference from above */
1555 config_item_put(item);
1557 module_put(dead_item_owner);
1558 module_put(subsys_owner);
1563 const struct inode_operations configfs_dir_inode_operations = {
1564 .mkdir = configfs_mkdir,
1565 .rmdir = configfs_rmdir,
1566 .symlink = configfs_symlink,
1567 .unlink = configfs_unlink,
1568 .lookup = configfs_lookup,
1569 .setattr = configfs_setattr,
1572 const struct inode_operations configfs_root_inode_operations = {
1573 .lookup = configfs_lookup,
1574 .setattr = configfs_setattr,
1577 static int configfs_dir_open(struct inode *inode, struct file *file)
1579 struct dentry * dentry = file->f_path.dentry;
1580 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1583 inode_lock(d_inode(dentry));
1585 * Fake invisibility if dir belongs to a group/default groups hierarchy
1589 if (configfs_dirent_is_ready(parent_sd)) {
1590 file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);
1591 if (IS_ERR(file->private_data))
1592 err = PTR_ERR(file->private_data);
1596 inode_unlock(d_inode(dentry));
1601 static int configfs_dir_close(struct inode *inode, struct file *file)
1603 struct dentry * dentry = file->f_path.dentry;
1604 struct configfs_dirent * cursor = file->private_data;
1606 inode_lock(d_inode(dentry));
1607 spin_lock(&configfs_dirent_lock);
1608 list_del_init(&cursor->s_sibling);
1609 spin_unlock(&configfs_dirent_lock);
1610 inode_unlock(d_inode(dentry));
1612 release_configfs_dirent(cursor);
1617 /* Relationship between s_mode and the DT_xxx types */
1618 static inline unsigned char dt_type(struct configfs_dirent *sd)
1620 return (sd->s_mode >> 12) & 15;
1623 static int configfs_readdir(struct file *file, struct dir_context *ctx)
1625 struct dentry *dentry = file->f_path.dentry;
1626 struct super_block *sb = dentry->d_sb;
1627 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1628 struct configfs_dirent *cursor = file->private_data;
1629 struct list_head *p, *q = &cursor->s_sibling;
1632 if (!dir_emit_dots(file, ctx))
1634 spin_lock(&configfs_dirent_lock);
1636 list_move(q, &parent_sd->s_children);
1637 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1638 struct configfs_dirent *next;
1641 struct inode *inode = NULL;
1643 next = list_entry(p, struct configfs_dirent, s_sibling);
1644 if (!next->s_element)
1648 * We'll have a dentry and an inode for
1649 * PINNED items and for open attribute
1650 * files. We lock here to prevent a race
1651 * with configfs_d_iput() clearing
1652 * s_dentry before calling iput().
1654 * Why do we go to the trouble? If
1655 * someone has an attribute file open,
1656 * the inode number should match until
1657 * they close it. Beyond that, we don't
1660 dentry = next->s_dentry;
1662 inode = d_inode(dentry);
1665 spin_unlock(&configfs_dirent_lock);
1667 ino = iunique(sb, 2);
1669 name = configfs_get_name(next);
1672 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1675 spin_lock(&configfs_dirent_lock);
1680 spin_unlock(&configfs_dirent_lock);
1684 static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1686 struct dentry * dentry = file->f_path.dentry;
1690 offset += file->f_pos;
1699 if (offset != file->f_pos) {
1700 file->f_pos = offset;
1701 if (file->f_pos >= 2) {
1702 struct configfs_dirent *sd = dentry->d_fsdata;
1703 struct configfs_dirent *cursor = file->private_data;
1704 struct list_head *p;
1705 loff_t n = file->f_pos - 2;
1707 spin_lock(&configfs_dirent_lock);
1708 list_del(&cursor->s_sibling);
1709 p = sd->s_children.next;
1710 while (n && p != &sd->s_children) {
1711 struct configfs_dirent *next;
1712 next = list_entry(p, struct configfs_dirent,
1714 if (next->s_element)
1718 list_add_tail(&cursor->s_sibling, p);
1719 spin_unlock(&configfs_dirent_lock);
1725 const struct file_operations configfs_dir_operations = {
1726 .open = configfs_dir_open,
1727 .release = configfs_dir_close,
1728 .llseek = configfs_dir_lseek,
1729 .read = generic_read_dir,
1730 .iterate_shared = configfs_readdir,
1734 * configfs_register_group - creates a parent-child relation between two groups
1735 * @parent_group: parent group
1736 * @group: child group
1738 * link groups, creates dentry for the child and attaches it to the
1741 * Return: 0 on success, negative errno code on error
1743 int configfs_register_group(struct config_group *parent_group,
1744 struct config_group *group)
1746 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1747 struct dentry *parent;
1748 struct configfs_fragment *frag;
1751 frag = new_fragment();
1755 mutex_lock(&subsys->su_mutex);
1756 link_group(parent_group, group);
1757 mutex_unlock(&subsys->su_mutex);
1759 parent = parent_group->cg_item.ci_dentry;
1761 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1762 ret = create_default_group(parent_group, group, frag);
1766 spin_lock(&configfs_dirent_lock);
1767 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1768 spin_unlock(&configfs_dirent_lock);
1769 inode_unlock(d_inode(parent));
1773 inode_unlock(d_inode(parent));
1774 mutex_lock(&subsys->su_mutex);
1775 unlink_group(group);
1776 mutex_unlock(&subsys->su_mutex);
1780 EXPORT_SYMBOL(configfs_register_group);
1783 * configfs_unregister_group() - unregisters a child group from its parent
1784 * @group: parent group to be unregistered
1786 * Undoes configfs_register_group()
1788 void configfs_unregister_group(struct config_group *group)
1790 struct configfs_subsystem *subsys = group->cg_subsys;
1791 struct dentry *dentry = group->cg_item.ci_dentry;
1792 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1793 struct configfs_dirent *sd = dentry->d_fsdata;
1794 struct configfs_fragment *frag = sd->s_frag;
1796 down_write(&frag->frag_sem);
1797 frag->frag_dead = true;
1798 up_write(&frag->frag_sem);
1800 inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
1801 spin_lock(&configfs_dirent_lock);
1802 configfs_detach_prep(dentry, NULL);
1803 spin_unlock(&configfs_dirent_lock);
1805 configfs_detach_group(&group->cg_item);
1806 d_inode(dentry)->i_flags |= S_DEAD;
1808 fsnotify_rmdir(d_inode(parent), dentry);
1810 inode_unlock(d_inode(parent));
1814 mutex_lock(&subsys->su_mutex);
1815 unlink_group(group);
1816 mutex_unlock(&subsys->su_mutex);
1818 EXPORT_SYMBOL(configfs_unregister_group);
1821 * configfs_register_default_group() - allocates and registers a child group
1822 * @parent_group: parent group
1823 * @name: child group name
1824 * @item_type: child item type description
1826 * boilerplate to allocate and register a child group with its parent. We need
1827 * kzalloc'ed memory because child's default_group is initially empty.
1829 * Return: allocated config group or ERR_PTR() on error
1831 struct config_group *
1832 configfs_register_default_group(struct config_group *parent_group,
1834 const struct config_item_type *item_type)
1837 struct config_group *group;
1839 group = kzalloc(sizeof(*group), GFP_KERNEL);
1841 return ERR_PTR(-ENOMEM);
1842 config_group_init_type_name(group, name, item_type);
1844 ret = configfs_register_group(parent_group, group);
1847 return ERR_PTR(ret);
1851 EXPORT_SYMBOL(configfs_register_default_group);
1854 * configfs_unregister_default_group() - unregisters and frees a child group
1855 * @group: the group to act on
1857 void configfs_unregister_default_group(struct config_group *group)
1859 configfs_unregister_group(group);
1862 EXPORT_SYMBOL(configfs_unregister_default_group);
1864 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1867 struct config_group *group = &subsys->su_group;
1868 struct dentry *dentry;
1869 struct dentry *root;
1870 struct configfs_dirent *sd;
1871 struct configfs_fragment *frag;
1873 frag = new_fragment();
1877 root = configfs_pin_fs();
1880 return PTR_ERR(root);
1883 if (!group->cg_item.ci_name)
1884 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1886 sd = root->d_fsdata;
1887 link_group(to_config_group(sd->s_element), group);
1889 inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
1892 dentry = d_alloc_name(root, group->cg_item.ci_name);
1894 d_add(dentry, NULL);
1896 err = configfs_attach_group(sd->s_element, &group->cg_item,
1899 BUG_ON(d_inode(dentry));
1903 spin_lock(&configfs_dirent_lock);
1904 configfs_dir_set_ready(dentry->d_fsdata);
1905 spin_unlock(&configfs_dirent_lock);
1909 inode_unlock(d_inode(root));
1912 unlink_group(group);
1913 configfs_release_fs();
1920 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1922 struct config_group *group = &subsys->su_group;
1923 struct dentry *dentry = group->cg_item.ci_dentry;
1924 struct dentry *root = dentry->d_sb->s_root;
1925 struct configfs_dirent *sd = dentry->d_fsdata;
1926 struct configfs_fragment *frag = sd->s_frag;
1928 if (dentry->d_parent != root) {
1929 pr_err("Tried to unregister non-subsystem!\n");
1933 down_write(&frag->frag_sem);
1934 frag->frag_dead = true;
1935 up_write(&frag->frag_sem);
1937 inode_lock_nested(d_inode(root),
1939 inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
1940 mutex_lock(&configfs_symlink_mutex);
1941 spin_lock(&configfs_dirent_lock);
1942 if (configfs_detach_prep(dentry, NULL)) {
1943 pr_err("Tried to unregister non-empty subsystem!\n");
1945 spin_unlock(&configfs_dirent_lock);
1946 mutex_unlock(&configfs_symlink_mutex);
1947 configfs_detach_group(&group->cg_item);
1948 d_inode(dentry)->i_flags |= S_DEAD;
1950 fsnotify_rmdir(d_inode(root), dentry);
1951 inode_unlock(d_inode(dentry));
1955 inode_unlock(d_inode(root));
1959 unlink_group(group);
1960 configfs_release_fs();
1963 EXPORT_SYMBOL(configfs_register_subsystem);
1964 EXPORT_SYMBOL(configfs_unregister_subsystem);