1 /* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
4 * dir.c - Operations for configfs directories.
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
16 * You should have received a copy of the GNU General Public
17 * License along with this program; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 021110-1307, USA.
22 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
24 * configfs Copyright (C) 2005 Oracle. All rights reserved.
30 #include <linux/mount.h>
31 #include <linux/module.h>
32 #include <linux/slab.h>
33 #include <linux/err.h>
35 #include <linux/configfs.h>
36 #include "configfs_internal.h"
38 DECLARE_RWSEM(configfs_rename_sem);
40 * Protects mutations of configfs_dirent linkage together with proper i_mutex
41 * Also protects mutations of symlinks linkage to target configfs_dirent
42 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
43 * and configfs_dirent_lock locked, in that order.
44 * This allows one to safely traverse configfs_dirent trees and symlinks without
45 * having to lock inodes.
47 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
48 * unlocked is not reliable unless in detach_groups() called from
49 * rmdir()/unregister() and from configfs_attach_group()
51 DEFINE_SPINLOCK(configfs_dirent_lock);
53 static void configfs_d_iput(struct dentry * dentry,
56 struct configfs_dirent *sd = dentry->d_fsdata;
59 /* Coordinate with configfs_readdir */
60 spin_lock(&configfs_dirent_lock);
61 /* Coordinate with configfs_attach_attr where will increase
62 * sd->s_count and update sd->s_dentry to new allocated one.
63 * Only set sd->dentry to null when this dentry is the only
65 * If not do so, configfs_d_iput may run just after
66 * configfs_attach_attr and set sd->s_dentry to null
67 * even it's still in use.
69 if (atomic_read(&sd->s_count) <= 2)
72 spin_unlock(&configfs_dirent_lock);
78 const struct dentry_operations configfs_dentry_ops = {
79 .d_iput = configfs_d_iput,
80 .d_delete = always_delete_dentry,
86 * Helpers to make lockdep happy with our recursive locking of default groups'
87 * inodes (see configfs_attach_group() and configfs_detach_group()).
88 * We put default groups i_mutexes in separate classes according to their depth
89 * from the youngest non-default group ancestor.
91 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
92 * groups A/B and A/C will have their inode's mutex in class
93 * default_group_class[0], and default group A/C/D will be in
94 * default_group_class[1].
96 * The lock classes are declared and assigned in inode.c, according to the
98 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
99 * default groups, and reset to -1 when all default groups are attached. During
100 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
101 * inode's mutex is set to default_group_class[s_depth - 1].
104 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
109 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
110 struct configfs_dirent *sd)
112 int parent_depth = parent_sd->s_depth;
114 if (parent_depth >= 0)
115 sd->s_depth = parent_depth + 1;
119 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
122 * item's i_mutex class is already setup, so s_depth is now only
123 * used to set new sub-directories s_depth, which is always done
124 * with item's i_mutex locked.
127 * sd->s_depth == -1 iff we are a non default group.
128 * else (we are a default group) sd->s_depth > 0 (see
131 if (sd->s_depth == -1)
133 * We are a non default group and we are going to create
140 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
142 /* We will not create default groups anymore. */
146 #else /* CONFIG_LOCKDEP */
148 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
152 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
153 struct configfs_dirent *sd)
158 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
163 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
167 #endif /* CONFIG_LOCKDEP */
170 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
172 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
173 void *element, int type)
175 struct configfs_dirent * sd;
177 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
179 return ERR_PTR(-ENOMEM);
181 atomic_set(&sd->s_count, 1);
182 INIT_LIST_HEAD(&sd->s_links);
183 INIT_LIST_HEAD(&sd->s_children);
184 sd->s_element = element;
186 configfs_init_dirent_depth(sd);
187 spin_lock(&configfs_dirent_lock);
188 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
189 spin_unlock(&configfs_dirent_lock);
190 kmem_cache_free(configfs_dir_cachep, sd);
191 return ERR_PTR(-ENOENT);
193 list_add(&sd->s_sibling, &parent_sd->s_children);
194 spin_unlock(&configfs_dirent_lock);
201 * Return -EEXIST if there is already a configfs element with the same
202 * name for the same parent.
204 * called with parent inode's i_mutex held
206 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
207 const unsigned char *new)
209 struct configfs_dirent * sd;
211 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
213 const unsigned char *existing = configfs_get_name(sd);
214 if (strcmp(existing, new))
225 int configfs_make_dirent(struct configfs_dirent * parent_sd,
226 struct dentry * dentry, void * element,
227 umode_t mode, int type)
229 struct configfs_dirent * sd;
231 sd = configfs_new_dirent(parent_sd, element, type);
236 sd->s_dentry = dentry;
238 dentry->d_fsdata = configfs_get(sd);
243 static void init_dir(struct inode * inode)
245 inode->i_op = &configfs_dir_inode_operations;
246 inode->i_fop = &configfs_dir_operations;
248 /* directory inodes start off with i_nlink == 2 (for "." entry) */
252 static void configfs_init_file(struct inode * inode)
254 inode->i_size = PAGE_SIZE;
255 inode->i_fop = &configfs_file_operations;
258 static void configfs_init_bin_file(struct inode *inode)
261 inode->i_fop = &configfs_bin_file_operations;
264 static void init_symlink(struct inode * inode)
266 inode->i_op = &configfs_symlink_inode_operations;
270 * configfs_create_dir - create a directory for an config_item.
271 * @item: config_itemwe're creating directory for.
272 * @dentry: config_item's dentry.
274 * Note: user-created entries won't be allowed under this new directory
275 * until it is validated by configfs_dir_set_ready()
278 static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
281 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
282 struct dentry *p = dentry->d_parent;
286 error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
290 error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
291 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
295 configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
296 error = configfs_create(dentry, mode, init_dir);
298 inc_nlink(d_inode(p));
299 item->ci_dentry = dentry;
301 struct configfs_dirent *sd = dentry->d_fsdata;
303 spin_lock(&configfs_dirent_lock);
304 list_del_init(&sd->s_sibling);
305 spin_unlock(&configfs_dirent_lock);
313 * Allow userspace to create new entries under a new directory created with
314 * configfs_create_dir(), and under all of its chidlren directories recursively.
315 * @sd configfs_dirent of the new directory to validate
317 * Caller must hold configfs_dirent_lock.
319 static void configfs_dir_set_ready(struct configfs_dirent *sd)
321 struct configfs_dirent *child_sd;
323 sd->s_type &= ~CONFIGFS_USET_CREATING;
324 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
325 if (child_sd->s_type & CONFIGFS_USET_CREATING)
326 configfs_dir_set_ready(child_sd);
330 * Check that a directory does not belong to a directory hierarchy being
331 * attached and not validated yet.
332 * @sd configfs_dirent of the directory to check
334 * @return non-zero iff the directory was validated
336 * Note: takes configfs_dirent_lock, so the result may change from false to true
337 * in two consecutive calls, but never from true to false.
339 int configfs_dirent_is_ready(struct configfs_dirent *sd)
343 spin_lock(&configfs_dirent_lock);
344 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
345 spin_unlock(&configfs_dirent_lock);
350 int configfs_create_link(struct configfs_symlink *sl,
351 struct dentry *parent,
352 struct dentry *dentry)
355 umode_t mode = S_IFLNK | S_IRWXUGO;
357 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
360 err = configfs_create(dentry, mode, init_symlink);
362 struct configfs_dirent *sd = dentry->d_fsdata;
364 spin_lock(&configfs_dirent_lock);
365 list_del_init(&sd->s_sibling);
366 spin_unlock(&configfs_dirent_lock);
374 static void remove_dir(struct dentry * d)
376 struct dentry * parent = dget(d->d_parent);
377 struct configfs_dirent * sd;
380 spin_lock(&configfs_dirent_lock);
381 list_del_init(&sd->s_sibling);
382 spin_unlock(&configfs_dirent_lock);
384 if (d_really_is_positive(d))
385 simple_rmdir(d_inode(parent),d);
387 pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
393 * configfs_remove_dir - remove an config_item's directory.
394 * @item: config_item we're removing.
396 * The only thing special about this is that we remove any files in
397 * the directory before we remove the directory, and we've inlined
398 * what used to be configfs_rmdir() below, instead of calling separately.
400 * Caller holds the mutex of the item's inode
403 static void configfs_remove_dir(struct config_item * item)
405 struct dentry * dentry = dget(item->ci_dentry);
412 * Drop reference from dget() on entrance.
418 /* attaches attribute's configfs_dirent to the dentry corresponding to the
421 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
423 struct configfs_attribute * attr = sd->s_element;
426 spin_lock(&configfs_dirent_lock);
427 dentry->d_fsdata = configfs_get(sd);
428 sd->s_dentry = dentry;
429 spin_unlock(&configfs_dirent_lock);
431 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
432 (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) ?
433 configfs_init_bin_file :
445 static struct dentry * configfs_lookup(struct inode *dir,
446 struct dentry *dentry,
449 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
450 struct configfs_dirent * sd;
455 * Fake invisibility if dir belongs to a group/default groups hierarchy
458 * This forbids userspace to read/write attributes of items which may
459 * not complete their initialization, since the dentries of the
460 * attributes won't be instantiated.
463 if (!configfs_dirent_is_ready(parent_sd))
466 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
467 if (sd->s_type & CONFIGFS_NOT_PINNED) {
468 const unsigned char * name = configfs_get_name(sd);
470 if (strcmp(name, dentry->d_name.name))
474 err = configfs_attach_attr(sd, dentry);
481 * If it doesn't exist and it isn't a NOT_PINNED item,
482 * it must be negative.
484 if (dentry->d_name.len > NAME_MAX)
485 return ERR_PTR(-ENAMETOOLONG);
495 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
496 * attributes and are removed by rmdir(). We recurse, setting
497 * CONFIGFS_USET_DROPPING on all children that are candidates for
499 * If there is an error, the caller will reset the flags via
500 * configfs_detach_rollback().
502 static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
504 struct configfs_dirent *parent_sd = dentry->d_fsdata;
505 struct configfs_dirent *sd;
508 /* Mark that we're trying to drop the group */
509 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
512 if (!list_empty(&parent_sd->s_links))
516 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
517 if (!sd->s_element ||
518 (sd->s_type & CONFIGFS_NOT_PINNED))
520 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
521 /* Abort if racing with mkdir() */
522 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
524 *wait_mutex = &d_inode(sd->s_dentry)->i_mutex;
529 * Yup, recursive. If there's a problem, blame
530 * deep nesting of default_groups
532 ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
546 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
549 static void configfs_detach_rollback(struct dentry *dentry)
551 struct configfs_dirent *parent_sd = dentry->d_fsdata;
552 struct configfs_dirent *sd;
554 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
556 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
557 if (sd->s_type & CONFIGFS_USET_DEFAULT)
558 configfs_detach_rollback(sd->s_dentry);
561 static void detach_attrs(struct config_item * item)
563 struct dentry * dentry = dget(item->ci_dentry);
564 struct configfs_dirent * parent_sd;
565 struct configfs_dirent * sd, * tmp;
570 pr_debug("configfs %s: dropping attrs for dir\n",
571 dentry->d_name.name);
573 parent_sd = dentry->d_fsdata;
574 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
575 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
577 spin_lock(&configfs_dirent_lock);
578 list_del_init(&sd->s_sibling);
579 spin_unlock(&configfs_dirent_lock);
580 configfs_drop_dentry(sd, dentry);
585 * Drop reference from dget() on entrance.
590 static int populate_attrs(struct config_item *item)
592 struct config_item_type *t = item->ci_type;
593 struct configfs_attribute *attr;
594 struct configfs_bin_attribute *bin_attr;
601 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
602 if ((error = configfs_create_file(item, attr)))
606 if (t->ct_bin_attrs) {
607 for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
608 error = configfs_create_bin_file(item, bin_attr);
620 static int configfs_attach_group(struct config_item *parent_item,
621 struct config_item *item,
622 struct dentry *dentry);
623 static void configfs_detach_group(struct config_item *item);
625 static void detach_groups(struct config_group *group)
627 struct dentry * dentry = dget(group->cg_item.ci_dentry);
628 struct dentry *child;
629 struct configfs_dirent *parent_sd;
630 struct configfs_dirent *sd, *tmp;
635 parent_sd = dentry->d_fsdata;
636 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
637 if (!sd->s_element ||
638 !(sd->s_type & CONFIGFS_USET_DEFAULT))
641 child = sd->s_dentry;
643 mutex_lock(&d_inode(child)->i_mutex);
645 configfs_detach_group(sd->s_element);
646 d_inode(child)->i_flags |= S_DEAD;
649 mutex_unlock(&d_inode(child)->i_mutex);
656 * Drop reference from dget() on entrance.
662 * This fakes mkdir(2) on a default_groups[] entry. It
663 * creates a dentry, attachs it, and then does fixup
666 * We could, perhaps, tweak our parent's ->mkdir for a minute and
667 * try using vfs_mkdir. Just a thought.
669 static int create_default_group(struct config_group *parent_group,
670 struct config_group *group)
673 struct configfs_dirent *sd;
674 /* We trust the caller holds a reference to parent */
675 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
677 if (!group->cg_item.ci_name)
678 group->cg_item.ci_name = group->cg_item.ci_namebuf;
681 child = d_alloc_name(parent, group->cg_item.ci_name);
685 ret = configfs_attach_group(&parent_group->cg_item,
686 &group->cg_item, child);
688 sd = child->d_fsdata;
689 sd->s_type |= CONFIGFS_USET_DEFAULT;
691 BUG_ON(d_inode(child));
700 static int populate_groups(struct config_group *group)
702 struct config_group *new_group;
706 if (group->default_groups) {
707 for (i = 0; group->default_groups[i]; i++) {
708 new_group = group->default_groups[i];
710 ret = create_default_group(group, new_group);
712 detach_groups(group);
722 * All of link_obj/unlink_obj/link_group/unlink_group require that
723 * subsys->su_mutex is held.
726 static void unlink_obj(struct config_item *item)
728 struct config_group *group;
730 group = item->ci_group;
732 list_del_init(&item->ci_entry);
734 item->ci_group = NULL;
735 item->ci_parent = NULL;
737 /* Drop the reference for ci_entry */
738 config_item_put(item);
740 /* Drop the reference for ci_parent */
741 config_group_put(group);
745 static void link_obj(struct config_item *parent_item, struct config_item *item)
748 * Parent seems redundant with group, but it makes certain
749 * traversals much nicer.
751 item->ci_parent = parent_item;
754 * We hold a reference on the parent for the child's ci_parent
757 item->ci_group = config_group_get(to_config_group(parent_item));
758 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
761 * We hold a reference on the child for ci_entry on the parent's
764 config_item_get(item);
767 static void unlink_group(struct config_group *group)
770 struct config_group *new_group;
772 if (group->default_groups) {
773 for (i = 0; group->default_groups[i]; i++) {
774 new_group = group->default_groups[i];
775 unlink_group(new_group);
779 group->cg_subsys = NULL;
780 unlink_obj(&group->cg_item);
783 static void link_group(struct config_group *parent_group, struct config_group *group)
786 struct config_group *new_group;
787 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
789 link_obj(&parent_group->cg_item, &group->cg_item);
791 if (parent_group->cg_subsys)
792 subsys = parent_group->cg_subsys;
793 else if (configfs_is_root(&parent_group->cg_item))
794 subsys = to_configfs_subsystem(group);
797 group->cg_subsys = subsys;
799 if (group->default_groups) {
800 for (i = 0; group->default_groups[i]; i++) {
801 new_group = group->default_groups[i];
802 link_group(group, new_group);
808 * The goal is that configfs_attach_item() (and
809 * configfs_attach_group()) can be called from either the VFS or this
810 * module. That is, they assume that the items have been created,
811 * the dentry allocated, and the dcache is all ready to go.
813 * If they fail, they must clean up after themselves as if they
814 * had never been called. The caller (VFS or local function) will
815 * handle cleaning up the dcache bits.
817 * configfs_detach_group() and configfs_detach_item() behave similarly on
818 * the way out. They assume that the proper semaphores are held, they
819 * clean up the configfs items, and they expect their callers will
820 * handle the dcache bits.
822 static int configfs_attach_item(struct config_item *parent_item,
823 struct config_item *item,
824 struct dentry *dentry)
828 ret = configfs_create_dir(item, dentry);
830 ret = populate_attrs(item);
833 * We are going to remove an inode and its dentry but
834 * the VFS may already have hit and used them. Thus,
835 * we must lock them as rmdir() would.
837 mutex_lock(&d_inode(dentry)->i_mutex);
838 configfs_remove_dir(item);
839 d_inode(dentry)->i_flags |= S_DEAD;
841 mutex_unlock(&d_inode(dentry)->i_mutex);
849 /* Caller holds the mutex of the item's inode */
850 static void configfs_detach_item(struct config_item *item)
853 configfs_remove_dir(item);
856 static int configfs_attach_group(struct config_item *parent_item,
857 struct config_item *item,
858 struct dentry *dentry)
861 struct configfs_dirent *sd;
863 ret = configfs_attach_item(parent_item, item, dentry);
865 sd = dentry->d_fsdata;
866 sd->s_type |= CONFIGFS_USET_DIR;
869 * FYI, we're faking mkdir in populate_groups()
870 * We must lock the group's inode to avoid races with the VFS
871 * which can already hit the inode and try to add/remove entries
874 * We must also lock the inode to remove it safely in case of
875 * error, as rmdir() would.
877 mutex_lock_nested(&d_inode(dentry)->i_mutex, I_MUTEX_CHILD);
878 configfs_adjust_dir_dirent_depth_before_populate(sd);
879 ret = populate_groups(to_config_group(item));
881 configfs_detach_item(item);
882 d_inode(dentry)->i_flags |= S_DEAD;
885 configfs_adjust_dir_dirent_depth_after_populate(sd);
886 mutex_unlock(&d_inode(dentry)->i_mutex);
894 /* Caller holds the mutex of the group's inode */
895 static void configfs_detach_group(struct config_item *item)
897 detach_groups(to_config_group(item));
898 configfs_detach_item(item);
902 * After the item has been detached from the filesystem view, we are
903 * ready to tear it out of the hierarchy. Notify the client before
904 * we do that so they can perform any cleanup that requires
905 * navigating the hierarchy. A client does not need to provide this
906 * callback. The subsystem semaphore MUST be held by the caller, and
907 * references must be valid for both items. It also assumes the
908 * caller has validated ci_type.
910 static void client_disconnect_notify(struct config_item *parent_item,
911 struct config_item *item)
913 struct config_item_type *type;
915 type = parent_item->ci_type;
918 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
919 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
924 * Drop the initial reference from make_item()/make_group()
925 * This function assumes that reference is held on item
926 * and that item holds a valid reference to the parent. Also, it
927 * assumes the caller has validated ci_type.
929 static void client_drop_item(struct config_item *parent_item,
930 struct config_item *item)
932 struct config_item_type *type;
934 type = parent_item->ci_type;
938 * If ->drop_item() exists, it is responsible for the
941 if (type->ct_group_ops && type->ct_group_ops->drop_item)
942 type->ct_group_ops->drop_item(to_config_group(parent_item),
945 config_item_put(item);
949 static void configfs_dump_one(struct configfs_dirent *sd, int level)
951 pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd));
953 #define type_print(_type) if (sd->s_type & _type) pr_info("%*s %s\n", level, " ", #_type);
954 type_print(CONFIGFS_ROOT);
955 type_print(CONFIGFS_DIR);
956 type_print(CONFIGFS_ITEM_ATTR);
957 type_print(CONFIGFS_ITEM_LINK);
958 type_print(CONFIGFS_USET_DIR);
959 type_print(CONFIGFS_USET_DEFAULT);
960 type_print(CONFIGFS_USET_DROPPING);
964 static int configfs_dump(struct configfs_dirent *sd, int level)
966 struct configfs_dirent *child_sd;
969 configfs_dump_one(sd, level);
971 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
974 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
975 ret = configfs_dump(child_sd, level + 2);
986 * configfs_depend_item() and configfs_undepend_item()
988 * WARNING: Do not call these from a configfs callback!
990 * This describes these functions and their helpers.
992 * Allow another kernel system to depend on a config_item. If this
993 * happens, the item cannot go away until the dependent can live without
994 * it. The idea is to give client modules as simple an interface as
995 * possible. When a system asks them to depend on an item, they just
996 * call configfs_depend_item(). If the item is live and the client
997 * driver is in good shape, we'll happily do the work for them.
999 * Why is the locking complex? Because configfs uses the VFS to handle
1000 * all locking, but this function is called outside the normal
1001 * VFS->configfs path. So it must take VFS locks to prevent the
1002 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1003 * why you can't call these functions underneath configfs callbacks.
1005 * Note, btw, that this can be called at *any* time, even when a configfs
1006 * subsystem isn't registered, or when configfs is loading or unloading.
1007 * Just like configfs_register_subsystem(). So we take the same
1008 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1009 * If we can find the target item in the
1010 * configfs tree, it must be part of the subsystem tree as well, so we
1011 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1012 * locking out mkdir() and rmdir(), who might be racing us.
1016 * configfs_depend_prep()
1018 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1019 * attributes. This is similar but not the same to configfs_detach_prep().
1020 * Note that configfs_detach_prep() expects the parent to be locked when it
1021 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1022 * do that so we can unlock it if we find nothing.
1024 * Here we do a depth-first search of the dentry hierarchy looking for
1026 * We deliberately ignore items tagged as dropping since they are virtually
1027 * dead, as well as items in the middle of attachment since they virtually
1028 * do not exist yet. This completes the locking out of racing mkdir() and
1030 * Note: subdirectories in the middle of attachment start with s_type =
1031 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1032 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1033 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1035 * If the target is not found, -ENOENT is bubbled up.
1037 * This adds a requirement that all config_items be unique!
1039 * This is recursive. There isn't
1040 * much on the stack, though, so folks that need this function - be careful
1041 * about your stack! Patches will be accepted to make it iterative.
1043 static int configfs_depend_prep(struct dentry *origin,
1044 struct config_item *target)
1046 struct configfs_dirent *child_sd, *sd;
1049 BUG_ON(!origin || !origin->d_fsdata);
1050 sd = origin->d_fsdata;
1052 if (sd->s_element == target) /* Boo-yah */
1055 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1056 if ((child_sd->s_type & CONFIGFS_DIR) &&
1057 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1058 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1059 ret = configfs_depend_prep(child_sd->s_dentry,
1062 goto out; /* Child path boo-yah */
1066 /* We looped all our children and didn't find target */
1073 int configfs_depend_item(struct configfs_subsystem *subsys,
1074 struct config_item *target)
1077 struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
1078 struct config_item *s_item = &subsys->su_group.cg_item;
1079 struct dentry *root;
1082 * Pin the configfs filesystem. This means we can safely access
1083 * the root of the configfs filesystem.
1085 root = configfs_pin_fs();
1087 return PTR_ERR(root);
1090 * Next, lock the root directory. We're going to check that the
1091 * subsystem is really registered, and so we need to lock out
1092 * configfs_[un]register_subsystem().
1094 mutex_lock(&d_inode(root)->i_mutex);
1096 root_sd = root->d_fsdata;
1098 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1099 if (p->s_type & CONFIGFS_DIR) {
1100 if (p->s_element == s_item) {
1112 /* Ok, now we can trust subsys/s_item */
1114 spin_lock(&configfs_dirent_lock);
1115 /* Scan the tree, return 0 if found */
1116 ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1118 goto out_unlock_dirent_lock;
1121 * We are sure that the item is not about to be removed by rmdir(), and
1122 * not in the middle of attachment by mkdir().
1124 p = target->ci_dentry->d_fsdata;
1125 p->s_dependent_count += 1;
1127 out_unlock_dirent_lock:
1128 spin_unlock(&configfs_dirent_lock);
1130 mutex_unlock(&d_inode(root)->i_mutex);
1133 * If we succeeded, the fs is pinned via other methods. If not,
1134 * we're done with it anyway. So release_fs() is always right.
1136 configfs_release_fs();
1140 EXPORT_SYMBOL(configfs_depend_item);
1143 * Release the dependent linkage. This is much simpler than
1144 * configfs_depend_item() because we know that that the client driver is
1145 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1147 void configfs_undepend_item(struct configfs_subsystem *subsys,
1148 struct config_item *target)
1150 struct configfs_dirent *sd;
1153 * Since we can trust everything is pinned, we just need
1154 * configfs_dirent_lock.
1156 spin_lock(&configfs_dirent_lock);
1158 sd = target->ci_dentry->d_fsdata;
1159 BUG_ON(sd->s_dependent_count < 1);
1161 sd->s_dependent_count -= 1;
1164 * After this unlock, we cannot trust the item to stay alive!
1165 * DO NOT REFERENCE item after this unlock.
1167 spin_unlock(&configfs_dirent_lock);
1169 EXPORT_SYMBOL(configfs_undepend_item);
1171 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1175 struct config_group *group = NULL;
1176 struct config_item *item = NULL;
1177 struct config_item *parent_item;
1178 struct configfs_subsystem *subsys;
1179 struct configfs_dirent *sd;
1180 struct config_item_type *type;
1181 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1184 sd = dentry->d_parent->d_fsdata;
1187 * Fake invisibility if dir belongs to a group/default groups hierarchy
1190 if (!configfs_dirent_is_ready(sd)) {
1195 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1200 /* Get a working ref for the duration of this function */
1201 parent_item = configfs_get_config_item(dentry->d_parent);
1202 type = parent_item->ci_type;
1203 subsys = to_config_group(parent_item)->cg_subsys;
1206 if (!type || !type->ct_group_ops ||
1207 (!type->ct_group_ops->make_group &&
1208 !type->ct_group_ops->make_item)) {
1209 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1214 * The subsystem may belong to a different module than the item
1215 * being created. We don't want to safely pin the new item but
1216 * fail to pin the subsystem it sits under.
1218 if (!subsys->su_group.cg_item.ci_type) {
1222 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1223 if (!try_module_get(subsys_owner)) {
1228 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1231 goto out_subsys_put;
1234 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1236 mutex_lock(&subsys->su_mutex);
1237 if (type->ct_group_ops->make_group) {
1238 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1240 group = ERR_PTR(-ENOMEM);
1241 if (!IS_ERR(group)) {
1242 link_group(to_config_group(parent_item), group);
1243 item = &group->cg_item;
1245 ret = PTR_ERR(group);
1247 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1249 item = ERR_PTR(-ENOMEM);
1251 link_obj(parent_item, item);
1253 ret = PTR_ERR(item);
1255 mutex_unlock(&subsys->su_mutex);
1260 * If ret != 0, then link_obj() was never called.
1261 * There are no extra references to clean up.
1263 goto out_subsys_put;
1267 * link_obj() has been called (via link_group() for groups).
1268 * From here on out, errors must clean that up.
1271 type = item->ci_type;
1277 new_item_owner = type->ct_owner;
1278 if (!try_module_get(new_item_owner)) {
1284 * I hate doing it this way, but if there is
1285 * an error, module_put() probably should
1286 * happen after any cleanup.
1291 * Make racing rmdir() fail if it did not tag parent with
1292 * CONFIGFS_USET_DROPPING
1293 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1294 * fail and let rmdir() terminate correctly
1296 spin_lock(&configfs_dirent_lock);
1297 /* This will make configfs_detach_prep() fail */
1298 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1299 spin_unlock(&configfs_dirent_lock);
1302 ret = configfs_attach_group(parent_item, item, dentry);
1304 ret = configfs_attach_item(parent_item, item, dentry);
1306 spin_lock(&configfs_dirent_lock);
1307 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1309 configfs_dir_set_ready(dentry->d_fsdata);
1310 spin_unlock(&configfs_dirent_lock);
1314 /* Tear down everything we built up */
1315 mutex_lock(&subsys->su_mutex);
1317 client_disconnect_notify(parent_item, item);
1319 unlink_group(group);
1322 client_drop_item(parent_item, item);
1324 mutex_unlock(&subsys->su_mutex);
1327 module_put(new_item_owner);
1332 module_put(subsys_owner);
1336 * link_obj()/link_group() took a reference from child->parent,
1337 * so the parent is safely pinned. We can drop our working
1340 config_item_put(parent_item);
1346 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1348 struct config_item *parent_item;
1349 struct config_item *item;
1350 struct configfs_subsystem *subsys;
1351 struct configfs_dirent *sd;
1352 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1355 sd = dentry->d_fsdata;
1356 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1359 /* Get a working ref until we have the child */
1360 parent_item = configfs_get_config_item(dentry->d_parent);
1361 subsys = to_config_group(parent_item)->cg_subsys;
1364 if (!parent_item->ci_type) {
1365 config_item_put(parent_item);
1369 /* configfs_mkdir() shouldn't have allowed this */
1370 BUG_ON(!subsys->su_group.cg_item.ci_type);
1371 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1374 * Ensure that no racing symlink() will make detach_prep() fail while
1375 * the new link is temporarily attached
1378 struct mutex *wait_mutex;
1380 mutex_lock(&configfs_symlink_mutex);
1381 spin_lock(&configfs_dirent_lock);
1383 * Here's where we check for dependents. We're protected by
1384 * configfs_dirent_lock.
1385 * If no dependent, atomically tag the item as dropping.
1387 ret = sd->s_dependent_count ? -EBUSY : 0;
1389 ret = configfs_detach_prep(dentry, &wait_mutex);
1391 configfs_detach_rollback(dentry);
1393 spin_unlock(&configfs_dirent_lock);
1394 mutex_unlock(&configfs_symlink_mutex);
1397 if (ret != -EAGAIN) {
1398 config_item_put(parent_item);
1402 /* Wait until the racing operation terminates */
1403 mutex_lock(wait_mutex);
1404 mutex_unlock(wait_mutex);
1406 } while (ret == -EAGAIN);
1408 /* Get a working ref for the duration of this function */
1409 item = configfs_get_config_item(dentry);
1411 /* Drop reference from above, item already holds one. */
1412 config_item_put(parent_item);
1415 dead_item_owner = item->ci_type->ct_owner;
1417 if (sd->s_type & CONFIGFS_USET_DIR) {
1418 configfs_detach_group(item);
1420 mutex_lock(&subsys->su_mutex);
1421 client_disconnect_notify(parent_item, item);
1422 unlink_group(to_config_group(item));
1424 configfs_detach_item(item);
1426 mutex_lock(&subsys->su_mutex);
1427 client_disconnect_notify(parent_item, item);
1431 client_drop_item(parent_item, item);
1432 mutex_unlock(&subsys->su_mutex);
1434 /* Drop our reference from above */
1435 config_item_put(item);
1437 module_put(dead_item_owner);
1438 module_put(subsys_owner);
1443 const struct inode_operations configfs_dir_inode_operations = {
1444 .mkdir = configfs_mkdir,
1445 .rmdir = configfs_rmdir,
1446 .symlink = configfs_symlink,
1447 .unlink = configfs_unlink,
1448 .lookup = configfs_lookup,
1449 .setattr = configfs_setattr,
1452 const struct inode_operations configfs_root_inode_operations = {
1453 .lookup = configfs_lookup,
1454 .setattr = configfs_setattr,
1458 int configfs_rename_dir(struct config_item * item, const char *new_name)
1461 struct dentry * new_dentry, * parent;
1463 if (!strcmp(config_item_name(item), new_name))
1469 down_write(&configfs_rename_sem);
1470 parent = item->parent->dentry;
1472 mutex_lock(&d_inode(parent)->i_mutex);
1474 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1475 if (!IS_ERR(new_dentry)) {
1476 if (d_really_is_negative(new_dentry)) {
1477 error = config_item_set_name(item, "%s", new_name);
1479 d_add(new_dentry, NULL);
1480 d_move(item->dentry, new_dentry);
1483 d_delete(new_dentry);
1488 mutex_unlock(&d_inode(parent)->i_mutex);
1489 up_write(&configfs_rename_sem);
1495 static int configfs_dir_open(struct inode *inode, struct file *file)
1497 struct dentry * dentry = file->f_path.dentry;
1498 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1501 mutex_lock(&d_inode(dentry)->i_mutex);
1503 * Fake invisibility if dir belongs to a group/default groups hierarchy
1507 if (configfs_dirent_is_ready(parent_sd)) {
1508 file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
1509 if (IS_ERR(file->private_data))
1510 err = PTR_ERR(file->private_data);
1514 mutex_unlock(&d_inode(dentry)->i_mutex);
1519 static int configfs_dir_close(struct inode *inode, struct file *file)
1521 struct dentry * dentry = file->f_path.dentry;
1522 struct configfs_dirent * cursor = file->private_data;
1524 mutex_lock(&d_inode(dentry)->i_mutex);
1525 spin_lock(&configfs_dirent_lock);
1526 list_del_init(&cursor->s_sibling);
1527 spin_unlock(&configfs_dirent_lock);
1528 mutex_unlock(&d_inode(dentry)->i_mutex);
1530 release_configfs_dirent(cursor);
1535 /* Relationship between s_mode and the DT_xxx types */
1536 static inline unsigned char dt_type(struct configfs_dirent *sd)
1538 return (sd->s_mode >> 12) & 15;
1541 static int configfs_readdir(struct file *file, struct dir_context *ctx)
1543 struct dentry *dentry = file->f_path.dentry;
1544 struct super_block *sb = dentry->d_sb;
1545 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1546 struct configfs_dirent *cursor = file->private_data;
1547 struct list_head *p, *q = &cursor->s_sibling;
1550 if (!dir_emit_dots(file, ctx))
1552 if (ctx->pos == 2) {
1553 spin_lock(&configfs_dirent_lock);
1554 list_move(q, &parent_sd->s_children);
1555 spin_unlock(&configfs_dirent_lock);
1557 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1558 struct configfs_dirent *next;
1561 struct inode *inode = NULL;
1563 next = list_entry(p, struct configfs_dirent, s_sibling);
1564 if (!next->s_element)
1567 name = configfs_get_name(next);
1571 * We'll have a dentry and an inode for
1572 * PINNED items and for open attribute
1573 * files. We lock here to prevent a race
1574 * with configfs_d_iput() clearing
1575 * s_dentry before calling iput().
1577 * Why do we go to the trouble? If
1578 * someone has an attribute file open,
1579 * the inode number should match until
1580 * they close it. Beyond that, we don't
1583 spin_lock(&configfs_dirent_lock);
1584 dentry = next->s_dentry;
1586 inode = d_inode(dentry);
1589 spin_unlock(&configfs_dirent_lock);
1591 ino = iunique(sb, 2);
1593 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1596 spin_lock(&configfs_dirent_lock);
1598 spin_unlock(&configfs_dirent_lock);
1605 static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1607 struct dentry * dentry = file->f_path.dentry;
1609 mutex_lock(&d_inode(dentry)->i_mutex);
1612 offset += file->f_pos;
1617 mutex_unlock(&d_inode(dentry)->i_mutex);
1620 if (offset != file->f_pos) {
1621 file->f_pos = offset;
1622 if (file->f_pos >= 2) {
1623 struct configfs_dirent *sd = dentry->d_fsdata;
1624 struct configfs_dirent *cursor = file->private_data;
1625 struct list_head *p;
1626 loff_t n = file->f_pos - 2;
1628 spin_lock(&configfs_dirent_lock);
1629 list_del(&cursor->s_sibling);
1630 p = sd->s_children.next;
1631 while (n && p != &sd->s_children) {
1632 struct configfs_dirent *next;
1633 next = list_entry(p, struct configfs_dirent,
1635 if (next->s_element)
1639 list_add_tail(&cursor->s_sibling, p);
1640 spin_unlock(&configfs_dirent_lock);
1643 mutex_unlock(&d_inode(dentry)->i_mutex);
1647 const struct file_operations configfs_dir_operations = {
1648 .open = configfs_dir_open,
1649 .release = configfs_dir_close,
1650 .llseek = configfs_dir_lseek,
1651 .read = generic_read_dir,
1652 .iterate = configfs_readdir,
1656 * configfs_register_group - creates a parent-child relation between two groups
1657 * @parent_group: parent group
1658 * @group: child group
1660 * link groups, creates dentry for the child and attaches it to the
1663 * Return: 0 on success, negative errno code on error
1665 int configfs_register_group(struct config_group *parent_group,
1666 struct config_group *group)
1668 struct configfs_subsystem *subsys = parent_group->cg_subsys;
1669 struct dentry *parent;
1672 mutex_lock(&subsys->su_mutex);
1673 link_group(parent_group, group);
1674 mutex_unlock(&subsys->su_mutex);
1676 parent = parent_group->cg_item.ci_dentry;
1678 mutex_lock_nested(&d_inode(parent)->i_mutex, I_MUTEX_PARENT);
1679 ret = create_default_group(parent_group, group);
1681 spin_lock(&configfs_dirent_lock);
1682 configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
1683 spin_unlock(&configfs_dirent_lock);
1685 mutex_unlock(&d_inode(parent)->i_mutex);
1688 EXPORT_SYMBOL(configfs_register_group);
1691 * configfs_unregister_group() - unregisters a child group from its parent
1692 * @group: parent group to be unregistered
1694 * Undoes configfs_register_group()
1696 void configfs_unregister_group(struct config_group *group)
1698 struct configfs_subsystem *subsys = group->cg_subsys;
1699 struct dentry *dentry = group->cg_item.ci_dentry;
1700 struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
1702 mutex_lock_nested(&d_inode(parent)->i_mutex, I_MUTEX_PARENT);
1703 spin_lock(&configfs_dirent_lock);
1704 configfs_detach_prep(dentry, NULL);
1705 spin_unlock(&configfs_dirent_lock);
1707 configfs_detach_group(&group->cg_item);
1708 d_inode(dentry)->i_flags |= S_DEAD;
1711 mutex_unlock(&d_inode(parent)->i_mutex);
1715 mutex_lock(&subsys->su_mutex);
1716 unlink_group(group);
1717 mutex_unlock(&subsys->su_mutex);
1719 EXPORT_SYMBOL(configfs_unregister_group);
1722 * configfs_register_default_group() - allocates and registers a child group
1723 * @parent_group: parent group
1724 * @name: child group name
1725 * @item_type: child item type description
1727 * boilerplate to allocate and register a child group with its parent. We need
1728 * kzalloc'ed memory because child's default_group is initially empty.
1730 * Return: allocated config group or ERR_PTR() on error
1732 struct config_group *
1733 configfs_register_default_group(struct config_group *parent_group,
1735 struct config_item_type *item_type)
1738 struct config_group *group;
1740 group = kzalloc(sizeof(*group), GFP_KERNEL);
1742 return ERR_PTR(-ENOMEM);
1743 config_group_init_type_name(group, name, item_type);
1745 ret = configfs_register_group(parent_group, group);
1748 return ERR_PTR(ret);
1752 EXPORT_SYMBOL(configfs_register_default_group);
1755 * configfs_unregister_default_group() - unregisters and frees a child group
1756 * @group: the group to act on
1758 void configfs_unregister_default_group(struct config_group *group)
1760 configfs_unregister_group(group);
1763 EXPORT_SYMBOL(configfs_unregister_default_group);
1765 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1768 struct config_group *group = &subsys->su_group;
1769 struct dentry *dentry;
1770 struct dentry *root;
1771 struct configfs_dirent *sd;
1773 root = configfs_pin_fs();
1775 return PTR_ERR(root);
1777 if (!group->cg_item.ci_name)
1778 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1780 sd = root->d_fsdata;
1781 link_group(to_config_group(sd->s_element), group);
1783 mutex_lock_nested(&d_inode(root)->i_mutex, I_MUTEX_PARENT);
1786 dentry = d_alloc_name(root, group->cg_item.ci_name);
1788 d_add(dentry, NULL);
1790 err = configfs_attach_group(sd->s_element, &group->cg_item,
1793 BUG_ON(d_inode(dentry));
1797 spin_lock(&configfs_dirent_lock);
1798 configfs_dir_set_ready(dentry->d_fsdata);
1799 spin_unlock(&configfs_dirent_lock);
1803 mutex_unlock(&d_inode(root)->i_mutex);
1806 unlink_group(group);
1807 configfs_release_fs();
1813 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1815 struct config_group *group = &subsys->su_group;
1816 struct dentry *dentry = group->cg_item.ci_dentry;
1817 struct dentry *root = dentry->d_sb->s_root;
1819 if (dentry->d_parent != root) {
1820 pr_err("Tried to unregister non-subsystem!\n");
1824 mutex_lock_nested(&d_inode(root)->i_mutex,
1826 mutex_lock_nested(&d_inode(dentry)->i_mutex, I_MUTEX_CHILD);
1827 mutex_lock(&configfs_symlink_mutex);
1828 spin_lock(&configfs_dirent_lock);
1829 if (configfs_detach_prep(dentry, NULL)) {
1830 pr_err("Tried to unregister non-empty subsystem!\n");
1832 spin_unlock(&configfs_dirent_lock);
1833 mutex_unlock(&configfs_symlink_mutex);
1834 configfs_detach_group(&group->cg_item);
1835 d_inode(dentry)->i_flags |= S_DEAD;
1837 mutex_unlock(&d_inode(dentry)->i_mutex);
1841 mutex_unlock(&d_inode(root)->i_mutex);
1845 unlink_group(group);
1846 configfs_release_fs();
1849 EXPORT_SYMBOL(configfs_register_subsystem);
1850 EXPORT_SYMBOL(configfs_unregister_subsystem);