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);
79 * We _must_ delete our dentries on last dput, as the chain-to-parent
80 * behavior is required to clear the parents of default_groups.
82 static int configfs_d_delete(const struct dentry *dentry)
87 const struct dentry_operations configfs_dentry_ops = {
88 .d_iput = configfs_d_iput,
89 /* simple_delete_dentry() isn't exported */
90 .d_delete = configfs_d_delete,
96 * Helpers to make lockdep happy with our recursive locking of default groups'
97 * inodes (see configfs_attach_group() and configfs_detach_group()).
98 * We put default groups i_mutexes in separate classes according to their depth
99 * from the youngest non-default group ancestor.
101 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
102 * groups A/B and A/C will have their inode's mutex in class
103 * default_group_class[0], and default group A/C/D will be in
104 * default_group_class[1].
106 * The lock classes are declared and assigned in inode.c, according to the
108 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
109 * default groups, and reset to -1 when all default groups are attached. During
110 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
111 * inode's mutex is set to default_group_class[s_depth - 1].
114 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
119 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
120 struct configfs_dirent *sd)
122 int parent_depth = parent_sd->s_depth;
124 if (parent_depth >= 0)
125 sd->s_depth = parent_depth + 1;
129 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
132 * item's i_mutex class is already setup, so s_depth is now only
133 * used to set new sub-directories s_depth, which is always done
134 * with item's i_mutex locked.
137 * sd->s_depth == -1 iff we are a non default group.
138 * else (we are a default group) sd->s_depth > 0 (see
141 if (sd->s_depth == -1)
143 * We are a non default group and we are going to create
150 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
152 /* We will not create default groups anymore. */
156 #else /* CONFIG_LOCKDEP */
158 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
162 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
163 struct configfs_dirent *sd)
168 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
173 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
177 #endif /* CONFIG_LOCKDEP */
180 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
182 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
183 void *element, int type)
185 struct configfs_dirent * sd;
187 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
189 return ERR_PTR(-ENOMEM);
191 atomic_set(&sd->s_count, 1);
192 INIT_LIST_HEAD(&sd->s_links);
193 INIT_LIST_HEAD(&sd->s_children);
194 sd->s_element = element;
196 configfs_init_dirent_depth(sd);
197 spin_lock(&configfs_dirent_lock);
198 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
199 spin_unlock(&configfs_dirent_lock);
200 kmem_cache_free(configfs_dir_cachep, sd);
201 return ERR_PTR(-ENOENT);
203 list_add(&sd->s_sibling, &parent_sd->s_children);
204 spin_unlock(&configfs_dirent_lock);
211 * Return -EEXIST if there is already a configfs element with the same
212 * name for the same parent.
214 * called with parent inode's i_mutex held
216 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
217 const unsigned char *new)
219 struct configfs_dirent * sd;
221 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
223 const unsigned char *existing = configfs_get_name(sd);
224 if (strcmp(existing, new))
235 int configfs_make_dirent(struct configfs_dirent * parent_sd,
236 struct dentry * dentry, void * element,
237 umode_t mode, int type)
239 struct configfs_dirent * sd;
241 sd = configfs_new_dirent(parent_sd, element, type);
246 sd->s_dentry = dentry;
248 dentry->d_fsdata = configfs_get(sd);
253 static int init_dir(struct inode * inode)
255 inode->i_op = &configfs_dir_inode_operations;
256 inode->i_fop = &configfs_dir_operations;
258 /* directory inodes start off with i_nlink == 2 (for "." entry) */
263 static int configfs_init_file(struct inode * inode)
265 inode->i_size = PAGE_SIZE;
266 inode->i_fop = &configfs_file_operations;
270 static int init_symlink(struct inode * inode)
272 inode->i_op = &configfs_symlink_inode_operations;
276 static int create_dir(struct config_item * k, struct dentry * p,
280 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
282 error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
284 error = configfs_make_dirent(p->d_fsdata, d, k, mode,
285 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
287 configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
288 error = configfs_create(d, mode, init_dir);
290 inc_nlink(p->d_inode);
292 struct configfs_dirent *sd = d->d_fsdata;
294 spin_lock(&configfs_dirent_lock);
295 list_del_init(&sd->s_sibling);
296 spin_unlock(&configfs_dirent_lock);
306 * configfs_create_dir - create a directory for an config_item.
307 * @item: config_itemwe're creating directory for.
308 * @dentry: config_item's dentry.
310 * Note: user-created entries won't be allowed under this new directory
311 * until it is validated by configfs_dir_set_ready()
314 static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
316 struct dentry * parent;
322 parent = item->ci_parent->ci_dentry;
323 else if (configfs_mount && configfs_mount->mnt_sb)
324 parent = configfs_mount->mnt_sb->s_root;
328 error = create_dir(item,parent,dentry);
330 item->ci_dentry = dentry;
335 * Allow userspace to create new entries under a new directory created with
336 * configfs_create_dir(), and under all of its chidlren directories recursively.
337 * @sd configfs_dirent of the new directory to validate
339 * Caller must hold configfs_dirent_lock.
341 static void configfs_dir_set_ready(struct configfs_dirent *sd)
343 struct configfs_dirent *child_sd;
345 sd->s_type &= ~CONFIGFS_USET_CREATING;
346 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
347 if (child_sd->s_type & CONFIGFS_USET_CREATING)
348 configfs_dir_set_ready(child_sd);
352 * Check that a directory does not belong to a directory hierarchy being
353 * attached and not validated yet.
354 * @sd configfs_dirent of the directory to check
356 * @return non-zero iff the directory was validated
358 * Note: takes configfs_dirent_lock, so the result may change from false to true
359 * in two consecutive calls, but never from true to false.
361 int configfs_dirent_is_ready(struct configfs_dirent *sd)
365 spin_lock(&configfs_dirent_lock);
366 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
367 spin_unlock(&configfs_dirent_lock);
372 int configfs_create_link(struct configfs_symlink *sl,
373 struct dentry *parent,
374 struct dentry *dentry)
377 umode_t mode = S_IFLNK | S_IRWXUGO;
379 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
382 err = configfs_create(dentry, mode, init_symlink);
384 struct configfs_dirent *sd = dentry->d_fsdata;
386 spin_lock(&configfs_dirent_lock);
387 list_del_init(&sd->s_sibling);
388 spin_unlock(&configfs_dirent_lock);
396 static void remove_dir(struct dentry * d)
398 struct dentry * parent = dget(d->d_parent);
399 struct configfs_dirent * sd;
402 spin_lock(&configfs_dirent_lock);
403 list_del_init(&sd->s_sibling);
404 spin_unlock(&configfs_dirent_lock);
407 simple_rmdir(parent->d_inode,d);
409 pr_debug(" o %s removing done (%d)\n",d->d_name.name, d->d_count);
415 * configfs_remove_dir - remove an config_item's directory.
416 * @item: config_item we're removing.
418 * The only thing special about this is that we remove any files in
419 * the directory before we remove the directory, and we've inlined
420 * what used to be configfs_rmdir() below, instead of calling separately.
422 * Caller holds the mutex of the item's inode
425 static void configfs_remove_dir(struct config_item * item)
427 struct dentry * dentry = dget(item->ci_dentry);
434 * Drop reference from dget() on entrance.
440 /* attaches attribute's configfs_dirent to the dentry corresponding to the
443 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
445 struct configfs_attribute * attr = sd->s_element;
448 spin_lock(&configfs_dirent_lock);
449 dentry->d_fsdata = configfs_get(sd);
450 sd->s_dentry = dentry;
451 spin_unlock(&configfs_dirent_lock);
453 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
465 static struct dentry * configfs_lookup(struct inode *dir,
466 struct dentry *dentry,
467 struct nameidata *nd)
469 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
470 struct configfs_dirent * sd;
475 * Fake invisibility if dir belongs to a group/default groups hierarchy
478 * This forbids userspace to read/write attributes of items which may
479 * not complete their initialization, since the dentries of the
480 * attributes won't be instantiated.
483 if (!configfs_dirent_is_ready(parent_sd))
486 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
487 if (sd->s_type & CONFIGFS_NOT_PINNED) {
488 const unsigned char * name = configfs_get_name(sd);
490 if (strcmp(name, dentry->d_name.name))
494 err = configfs_attach_attr(sd, dentry);
501 * If it doesn't exist and it isn't a NOT_PINNED item,
502 * it must be negative.
504 if (dentry->d_name.len > NAME_MAX)
505 return ERR_PTR(-ENAMETOOLONG);
515 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
516 * attributes and are removed by rmdir(). We recurse, setting
517 * CONFIGFS_USET_DROPPING on all children that are candidates for
519 * If there is an error, the caller will reset the flags via
520 * configfs_detach_rollback().
522 static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
524 struct configfs_dirent *parent_sd = dentry->d_fsdata;
525 struct configfs_dirent *sd;
528 /* Mark that we're trying to drop the group */
529 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
532 if (!list_empty(&parent_sd->s_links))
536 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
537 if (!sd->s_element ||
538 (sd->s_type & CONFIGFS_NOT_PINNED))
540 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
541 /* Abort if racing with mkdir() */
542 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
544 *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
549 * Yup, recursive. If there's a problem, blame
550 * deep nesting of default_groups
552 ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
566 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
569 static void configfs_detach_rollback(struct dentry *dentry)
571 struct configfs_dirent *parent_sd = dentry->d_fsdata;
572 struct configfs_dirent *sd;
574 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
576 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
577 if (sd->s_type & CONFIGFS_USET_DEFAULT)
578 configfs_detach_rollback(sd->s_dentry);
581 static void detach_attrs(struct config_item * item)
583 struct dentry * dentry = dget(item->ci_dentry);
584 struct configfs_dirent * parent_sd;
585 struct configfs_dirent * sd, * tmp;
590 pr_debug("configfs %s: dropping attrs for dir\n",
591 dentry->d_name.name);
593 parent_sd = dentry->d_fsdata;
594 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
595 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
597 spin_lock(&configfs_dirent_lock);
598 list_del_init(&sd->s_sibling);
599 spin_unlock(&configfs_dirent_lock);
600 configfs_drop_dentry(sd, dentry);
605 * Drop reference from dget() on entrance.
610 static int populate_attrs(struct config_item *item)
612 struct config_item_type *t = item->ci_type;
613 struct configfs_attribute *attr;
620 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
621 if ((error = configfs_create_file(item, attr)))
632 static int configfs_attach_group(struct config_item *parent_item,
633 struct config_item *item,
634 struct dentry *dentry);
635 static void configfs_detach_group(struct config_item *item);
637 static void detach_groups(struct config_group *group)
639 struct dentry * dentry = dget(group->cg_item.ci_dentry);
640 struct dentry *child;
641 struct configfs_dirent *parent_sd;
642 struct configfs_dirent *sd, *tmp;
647 parent_sd = dentry->d_fsdata;
648 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
649 if (!sd->s_element ||
650 !(sd->s_type & CONFIGFS_USET_DEFAULT))
653 child = sd->s_dentry;
655 mutex_lock(&child->d_inode->i_mutex);
657 configfs_detach_group(sd->s_element);
658 child->d_inode->i_flags |= S_DEAD;
661 mutex_unlock(&child->d_inode->i_mutex);
668 * Drop reference from dget() on entrance.
674 * This fakes mkdir(2) on a default_groups[] entry. It
675 * creates a dentry, attachs it, and then does fixup
678 * We could, perhaps, tweak our parent's ->mkdir for a minute and
679 * try using vfs_mkdir. Just a thought.
681 static int create_default_group(struct config_group *parent_group,
682 struct config_group *group)
686 struct configfs_dirent *sd;
687 /* We trust the caller holds a reference to parent */
688 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
690 if (!group->cg_item.ci_name)
691 group->cg_item.ci_name = group->cg_item.ci_namebuf;
692 name.name = group->cg_item.ci_name;
693 name.len = strlen(name.name);
694 name.hash = full_name_hash(name.name, name.len);
697 child = d_alloc(parent, &name);
701 ret = configfs_attach_group(&parent_group->cg_item,
702 &group->cg_item, child);
704 sd = child->d_fsdata;
705 sd->s_type |= CONFIGFS_USET_DEFAULT;
707 BUG_ON(child->d_inode);
716 static int populate_groups(struct config_group *group)
718 struct config_group *new_group;
722 if (group->default_groups) {
723 for (i = 0; group->default_groups[i]; i++) {
724 new_group = group->default_groups[i];
726 ret = create_default_group(group, new_group);
728 detach_groups(group);
738 * All of link_obj/unlink_obj/link_group/unlink_group require that
739 * subsys->su_mutex is held.
742 static void unlink_obj(struct config_item *item)
744 struct config_group *group;
746 group = item->ci_group;
748 list_del_init(&item->ci_entry);
750 item->ci_group = NULL;
751 item->ci_parent = NULL;
753 /* Drop the reference for ci_entry */
754 config_item_put(item);
756 /* Drop the reference for ci_parent */
757 config_group_put(group);
761 static void link_obj(struct config_item *parent_item, struct config_item *item)
764 * Parent seems redundant with group, but it makes certain
765 * traversals much nicer.
767 item->ci_parent = parent_item;
770 * We hold a reference on the parent for the child's ci_parent
773 item->ci_group = config_group_get(to_config_group(parent_item));
774 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
777 * We hold a reference on the child for ci_entry on the parent's
780 config_item_get(item);
783 static void unlink_group(struct config_group *group)
786 struct config_group *new_group;
788 if (group->default_groups) {
789 for (i = 0; group->default_groups[i]; i++) {
790 new_group = group->default_groups[i];
791 unlink_group(new_group);
795 group->cg_subsys = NULL;
796 unlink_obj(&group->cg_item);
799 static void link_group(struct config_group *parent_group, struct config_group *group)
802 struct config_group *new_group;
803 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
805 link_obj(&parent_group->cg_item, &group->cg_item);
807 if (parent_group->cg_subsys)
808 subsys = parent_group->cg_subsys;
809 else if (configfs_is_root(&parent_group->cg_item))
810 subsys = to_configfs_subsystem(group);
813 group->cg_subsys = subsys;
815 if (group->default_groups) {
816 for (i = 0; group->default_groups[i]; i++) {
817 new_group = group->default_groups[i];
818 link_group(group, new_group);
824 * The goal is that configfs_attach_item() (and
825 * configfs_attach_group()) can be called from either the VFS or this
826 * module. That is, they assume that the items have been created,
827 * the dentry allocated, and the dcache is all ready to go.
829 * If they fail, they must clean up after themselves as if they
830 * had never been called. The caller (VFS or local function) will
831 * handle cleaning up the dcache bits.
833 * configfs_detach_group() and configfs_detach_item() behave similarly on
834 * the way out. They assume that the proper semaphores are held, they
835 * clean up the configfs items, and they expect their callers will
836 * handle the dcache bits.
838 static int configfs_attach_item(struct config_item *parent_item,
839 struct config_item *item,
840 struct dentry *dentry)
844 ret = configfs_create_dir(item, dentry);
846 ret = populate_attrs(item);
849 * We are going to remove an inode and its dentry but
850 * the VFS may already have hit and used them. Thus,
851 * we must lock them as rmdir() would.
853 mutex_lock(&dentry->d_inode->i_mutex);
854 configfs_remove_dir(item);
855 dentry->d_inode->i_flags |= S_DEAD;
857 mutex_unlock(&dentry->d_inode->i_mutex);
865 /* Caller holds the mutex of the item's inode */
866 static void configfs_detach_item(struct config_item *item)
869 configfs_remove_dir(item);
872 static int configfs_attach_group(struct config_item *parent_item,
873 struct config_item *item,
874 struct dentry *dentry)
877 struct configfs_dirent *sd;
879 ret = configfs_attach_item(parent_item, item, dentry);
881 sd = dentry->d_fsdata;
882 sd->s_type |= CONFIGFS_USET_DIR;
885 * FYI, we're faking mkdir in populate_groups()
886 * We must lock the group's inode to avoid races with the VFS
887 * which can already hit the inode and try to add/remove entries
890 * We must also lock the inode to remove it safely in case of
891 * error, as rmdir() would.
893 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
894 configfs_adjust_dir_dirent_depth_before_populate(sd);
895 ret = populate_groups(to_config_group(item));
897 configfs_detach_item(item);
898 dentry->d_inode->i_flags |= S_DEAD;
901 configfs_adjust_dir_dirent_depth_after_populate(sd);
902 mutex_unlock(&dentry->d_inode->i_mutex);
910 /* Caller holds the mutex of the group's inode */
911 static void configfs_detach_group(struct config_item *item)
913 detach_groups(to_config_group(item));
914 configfs_detach_item(item);
918 * After the item has been detached from the filesystem view, we are
919 * ready to tear it out of the hierarchy. Notify the client before
920 * we do that so they can perform any cleanup that requires
921 * navigating the hierarchy. A client does not need to provide this
922 * callback. The subsystem semaphore MUST be held by the caller, and
923 * references must be valid for both items. It also assumes the
924 * caller has validated ci_type.
926 static void client_disconnect_notify(struct config_item *parent_item,
927 struct config_item *item)
929 struct config_item_type *type;
931 type = parent_item->ci_type;
934 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
935 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
940 * Drop the initial reference from make_item()/make_group()
941 * This function assumes that reference is held on item
942 * and that item holds a valid reference to the parent. Also, it
943 * assumes the caller has validated ci_type.
945 static void client_drop_item(struct config_item *parent_item,
946 struct config_item *item)
948 struct config_item_type *type;
950 type = parent_item->ci_type;
954 * If ->drop_item() exists, it is responsible for the
957 if (type->ct_group_ops && type->ct_group_ops->drop_item)
958 type->ct_group_ops->drop_item(to_config_group(parent_item),
961 config_item_put(item);
965 static void configfs_dump_one(struct configfs_dirent *sd, int level)
967 printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
969 #define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
970 type_print(CONFIGFS_ROOT);
971 type_print(CONFIGFS_DIR);
972 type_print(CONFIGFS_ITEM_ATTR);
973 type_print(CONFIGFS_ITEM_LINK);
974 type_print(CONFIGFS_USET_DIR);
975 type_print(CONFIGFS_USET_DEFAULT);
976 type_print(CONFIGFS_USET_DROPPING);
980 static int configfs_dump(struct configfs_dirent *sd, int level)
982 struct configfs_dirent *child_sd;
985 configfs_dump_one(sd, level);
987 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
990 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
991 ret = configfs_dump(child_sd, level + 2);
1002 * configfs_depend_item() and configfs_undepend_item()
1004 * WARNING: Do not call these from a configfs callback!
1006 * This describes these functions and their helpers.
1008 * Allow another kernel system to depend on a config_item. If this
1009 * happens, the item cannot go away until the dependent can live without
1010 * it. The idea is to give client modules as simple an interface as
1011 * possible. When a system asks them to depend on an item, they just
1012 * call configfs_depend_item(). If the item is live and the client
1013 * driver is in good shape, we'll happily do the work for them.
1015 * Why is the locking complex? Because configfs uses the VFS to handle
1016 * all locking, but this function is called outside the normal
1017 * VFS->configfs path. So it must take VFS locks to prevent the
1018 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1019 * why you can't call these functions underneath configfs callbacks.
1021 * Note, btw, that this can be called at *any* time, even when a configfs
1022 * subsystem isn't registered, or when configfs is loading or unloading.
1023 * Just like configfs_register_subsystem(). So we take the same
1024 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
1025 * If we can find the target item in the
1026 * configfs tree, it must be part of the subsystem tree as well, so we
1027 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
1028 * locking out mkdir() and rmdir(), who might be racing us.
1032 * configfs_depend_prep()
1034 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1035 * attributes. This is similar but not the same to configfs_detach_prep().
1036 * Note that configfs_detach_prep() expects the parent to be locked when it
1037 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1038 * do that so we can unlock it if we find nothing.
1040 * Here we do a depth-first search of the dentry hierarchy looking for
1042 * We deliberately ignore items tagged as dropping since they are virtually
1043 * dead, as well as items in the middle of attachment since they virtually
1044 * do not exist yet. This completes the locking out of racing mkdir() and
1046 * Note: subdirectories in the middle of attachment start with s_type =
1047 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1048 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1049 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1051 * If the target is not found, -ENOENT is bubbled up.
1053 * This adds a requirement that all config_items be unique!
1055 * This is recursive. There isn't
1056 * much on the stack, though, so folks that need this function - be careful
1057 * about your stack! Patches will be accepted to make it iterative.
1059 static int configfs_depend_prep(struct dentry *origin,
1060 struct config_item *target)
1062 struct configfs_dirent *child_sd, *sd = origin->d_fsdata;
1065 BUG_ON(!origin || !sd);
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 int configfs_depend_item(struct configfs_subsystem *subsys,
1089 struct config_item *target)
1092 struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
1093 struct config_item *s_item = &subsys->su_group.cg_item;
1096 * Pin the configfs filesystem. This means we can safely access
1097 * the root of the configfs filesystem.
1099 ret = configfs_pin_fs();
1104 * Next, lock the root directory. We're going to check that the
1105 * subsystem is really registered, and so we need to lock out
1106 * configfs_[un]register_subsystem().
1108 mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1110 root_sd = configfs_sb->s_root->d_fsdata;
1112 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1113 if (p->s_type & CONFIGFS_DIR) {
1114 if (p->s_element == s_item) {
1126 /* Ok, now we can trust subsys/s_item */
1128 spin_lock(&configfs_dirent_lock);
1129 /* Scan the tree, return 0 if found */
1130 ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1132 goto out_unlock_dirent_lock;
1135 * We are sure that the item is not about to be removed by rmdir(), and
1136 * not in the middle of attachment by mkdir().
1138 p = target->ci_dentry->d_fsdata;
1139 p->s_dependent_count += 1;
1141 out_unlock_dirent_lock:
1142 spin_unlock(&configfs_dirent_lock);
1144 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1147 * If we succeeded, the fs is pinned via other methods. If not,
1148 * we're done with it anyway. So release_fs() is always right.
1150 configfs_release_fs();
1154 EXPORT_SYMBOL(configfs_depend_item);
1157 * Release the dependent linkage. This is much simpler than
1158 * configfs_depend_item() because we know that that the client driver is
1159 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1161 void configfs_undepend_item(struct configfs_subsystem *subsys,
1162 struct config_item *target)
1164 struct configfs_dirent *sd;
1167 * Since we can trust everything is pinned, we just need
1168 * configfs_dirent_lock.
1170 spin_lock(&configfs_dirent_lock);
1172 sd = target->ci_dentry->d_fsdata;
1173 BUG_ON(sd->s_dependent_count < 1);
1175 sd->s_dependent_count -= 1;
1178 * After this unlock, we cannot trust the item to stay alive!
1179 * DO NOT REFERENCE item after this unlock.
1181 spin_unlock(&configfs_dirent_lock);
1183 EXPORT_SYMBOL(configfs_undepend_item);
1185 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1189 struct config_group *group = NULL;
1190 struct config_item *item = NULL;
1191 struct config_item *parent_item;
1192 struct configfs_subsystem *subsys;
1193 struct configfs_dirent *sd;
1194 struct config_item_type *type;
1195 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1198 if (dentry->d_parent == configfs_sb->s_root) {
1203 sd = dentry->d_parent->d_fsdata;
1206 * Fake invisibility if dir belongs to a group/default groups hierarchy
1209 if (!configfs_dirent_is_ready(sd)) {
1214 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1219 /* Get a working ref for the duration of this function */
1220 parent_item = configfs_get_config_item(dentry->d_parent);
1221 type = parent_item->ci_type;
1222 subsys = to_config_group(parent_item)->cg_subsys;
1225 if (!type || !type->ct_group_ops ||
1226 (!type->ct_group_ops->make_group &&
1227 !type->ct_group_ops->make_item)) {
1228 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1233 * The subsystem may belong to a different module than the item
1234 * being created. We don't want to safely pin the new item but
1235 * fail to pin the subsystem it sits under.
1237 if (!subsys->su_group.cg_item.ci_type) {
1241 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1242 if (!try_module_get(subsys_owner)) {
1247 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1250 goto out_subsys_put;
1253 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1255 mutex_lock(&subsys->su_mutex);
1256 if (type->ct_group_ops->make_group) {
1257 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1259 group = ERR_PTR(-ENOMEM);
1260 if (!IS_ERR(group)) {
1261 link_group(to_config_group(parent_item), group);
1262 item = &group->cg_item;
1264 ret = PTR_ERR(group);
1266 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1268 item = ERR_PTR(-ENOMEM);
1270 link_obj(parent_item, item);
1272 ret = PTR_ERR(item);
1274 mutex_unlock(&subsys->su_mutex);
1279 * If ret != 0, then link_obj() was never called.
1280 * There are no extra references to clean up.
1282 goto out_subsys_put;
1286 * link_obj() has been called (via link_group() for groups).
1287 * From here on out, errors must clean that up.
1290 type = item->ci_type;
1296 new_item_owner = type->ct_owner;
1297 if (!try_module_get(new_item_owner)) {
1303 * I hate doing it this way, but if there is
1304 * an error, module_put() probably should
1305 * happen after any cleanup.
1310 * Make racing rmdir() fail if it did not tag parent with
1311 * CONFIGFS_USET_DROPPING
1312 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1313 * fail and let rmdir() terminate correctly
1315 spin_lock(&configfs_dirent_lock);
1316 /* This will make configfs_detach_prep() fail */
1317 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1318 spin_unlock(&configfs_dirent_lock);
1321 ret = configfs_attach_group(parent_item, item, dentry);
1323 ret = configfs_attach_item(parent_item, item, dentry);
1325 spin_lock(&configfs_dirent_lock);
1326 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1328 configfs_dir_set_ready(dentry->d_fsdata);
1329 spin_unlock(&configfs_dirent_lock);
1333 /* Tear down everything we built up */
1334 mutex_lock(&subsys->su_mutex);
1336 client_disconnect_notify(parent_item, item);
1338 unlink_group(group);
1341 client_drop_item(parent_item, item);
1343 mutex_unlock(&subsys->su_mutex);
1346 module_put(new_item_owner);
1351 module_put(subsys_owner);
1355 * link_obj()/link_group() took a reference from child->parent,
1356 * so the parent is safely pinned. We can drop our working
1359 config_item_put(parent_item);
1365 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1367 struct config_item *parent_item;
1368 struct config_item *item;
1369 struct configfs_subsystem *subsys;
1370 struct configfs_dirent *sd;
1371 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1374 if (dentry->d_parent == configfs_sb->s_root)
1377 sd = dentry->d_fsdata;
1378 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1381 /* Get a working ref until we have the child */
1382 parent_item = configfs_get_config_item(dentry->d_parent);
1383 subsys = to_config_group(parent_item)->cg_subsys;
1386 if (!parent_item->ci_type) {
1387 config_item_put(parent_item);
1391 /* configfs_mkdir() shouldn't have allowed this */
1392 BUG_ON(!subsys->su_group.cg_item.ci_type);
1393 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1396 * Ensure that no racing symlink() will make detach_prep() fail while
1397 * the new link is temporarily attached
1400 struct mutex *wait_mutex;
1402 mutex_lock(&configfs_symlink_mutex);
1403 spin_lock(&configfs_dirent_lock);
1405 * Here's where we check for dependents. We're protected by
1406 * configfs_dirent_lock.
1407 * If no dependent, atomically tag the item as dropping.
1409 ret = sd->s_dependent_count ? -EBUSY : 0;
1411 ret = configfs_detach_prep(dentry, &wait_mutex);
1413 configfs_detach_rollback(dentry);
1415 spin_unlock(&configfs_dirent_lock);
1416 mutex_unlock(&configfs_symlink_mutex);
1419 if (ret != -EAGAIN) {
1420 config_item_put(parent_item);
1424 /* Wait until the racing operation terminates */
1425 mutex_lock(wait_mutex);
1426 mutex_unlock(wait_mutex);
1428 } while (ret == -EAGAIN);
1430 /* Get a working ref for the duration of this function */
1431 item = configfs_get_config_item(dentry);
1433 /* Drop reference from above, item already holds one. */
1434 config_item_put(parent_item);
1437 dead_item_owner = item->ci_type->ct_owner;
1439 if (sd->s_type & CONFIGFS_USET_DIR) {
1440 configfs_detach_group(item);
1442 mutex_lock(&subsys->su_mutex);
1443 client_disconnect_notify(parent_item, item);
1444 unlink_group(to_config_group(item));
1446 configfs_detach_item(item);
1448 mutex_lock(&subsys->su_mutex);
1449 client_disconnect_notify(parent_item, item);
1453 client_drop_item(parent_item, item);
1454 mutex_unlock(&subsys->su_mutex);
1456 /* Drop our reference from above */
1457 config_item_put(item);
1459 module_put(dead_item_owner);
1460 module_put(subsys_owner);
1465 const struct inode_operations configfs_dir_inode_operations = {
1466 .mkdir = configfs_mkdir,
1467 .rmdir = configfs_rmdir,
1468 .symlink = configfs_symlink,
1469 .unlink = configfs_unlink,
1470 .lookup = configfs_lookup,
1471 .setattr = configfs_setattr,
1475 int configfs_rename_dir(struct config_item * item, const char *new_name)
1478 struct dentry * new_dentry, * parent;
1480 if (!strcmp(config_item_name(item), new_name))
1486 down_write(&configfs_rename_sem);
1487 parent = item->parent->dentry;
1489 mutex_lock(&parent->d_inode->i_mutex);
1491 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1492 if (!IS_ERR(new_dentry)) {
1493 if (!new_dentry->d_inode) {
1494 error = config_item_set_name(item, "%s", new_name);
1496 d_add(new_dentry, NULL);
1497 d_move(item->dentry, new_dentry);
1500 d_delete(new_dentry);
1505 mutex_unlock(&parent->d_inode->i_mutex);
1506 up_write(&configfs_rename_sem);
1512 static int configfs_dir_open(struct inode *inode, struct file *file)
1514 struct dentry * dentry = file->f_path.dentry;
1515 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1518 mutex_lock(&dentry->d_inode->i_mutex);
1520 * Fake invisibility if dir belongs to a group/default groups hierarchy
1524 if (configfs_dirent_is_ready(parent_sd)) {
1525 file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
1526 if (IS_ERR(file->private_data))
1527 err = PTR_ERR(file->private_data);
1531 mutex_unlock(&dentry->d_inode->i_mutex);
1536 static int configfs_dir_close(struct inode *inode, struct file *file)
1538 struct dentry * dentry = file->f_path.dentry;
1539 struct configfs_dirent * cursor = file->private_data;
1541 mutex_lock(&dentry->d_inode->i_mutex);
1542 spin_lock(&configfs_dirent_lock);
1543 list_del_init(&cursor->s_sibling);
1544 spin_unlock(&configfs_dirent_lock);
1545 mutex_unlock(&dentry->d_inode->i_mutex);
1547 release_configfs_dirent(cursor);
1552 /* Relationship between s_mode and the DT_xxx types */
1553 static inline unsigned char dt_type(struct configfs_dirent *sd)
1555 return (sd->s_mode >> 12) & 15;
1558 static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
1560 struct dentry *dentry = filp->f_path.dentry;
1561 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1562 struct configfs_dirent *cursor = filp->private_data;
1563 struct list_head *p, *q = &cursor->s_sibling;
1565 int i = filp->f_pos;
1569 ino = dentry->d_inode->i_ino;
1570 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1576 ino = parent_ino(dentry);
1577 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1583 if (filp->f_pos == 2) {
1584 spin_lock(&configfs_dirent_lock);
1585 list_move(q, &parent_sd->s_children);
1586 spin_unlock(&configfs_dirent_lock);
1588 for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
1589 struct configfs_dirent *next;
1592 struct inode *inode = NULL;
1594 next = list_entry(p, struct configfs_dirent,
1596 if (!next->s_element)
1599 name = configfs_get_name(next);
1603 * We'll have a dentry and an inode for
1604 * PINNED items and for open attribute
1605 * files. We lock here to prevent a race
1606 * with configfs_d_iput() clearing
1607 * s_dentry before calling iput().
1609 * Why do we go to the trouble? If
1610 * someone has an attribute file open,
1611 * the inode number should match until
1612 * they close it. Beyond that, we don't
1615 spin_lock(&configfs_dirent_lock);
1616 dentry = next->s_dentry;
1618 inode = dentry->d_inode;
1621 spin_unlock(&configfs_dirent_lock);
1623 ino = iunique(configfs_sb, 2);
1625 if (filldir(dirent, name, len, filp->f_pos, ino,
1629 spin_lock(&configfs_dirent_lock);
1631 spin_unlock(&configfs_dirent_lock);
1639 static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
1641 struct dentry * dentry = file->f_path.dentry;
1643 mutex_lock(&dentry->d_inode->i_mutex);
1646 offset += file->f_pos;
1651 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
1654 if (offset != file->f_pos) {
1655 file->f_pos = offset;
1656 if (file->f_pos >= 2) {
1657 struct configfs_dirent *sd = dentry->d_fsdata;
1658 struct configfs_dirent *cursor = file->private_data;
1659 struct list_head *p;
1660 loff_t n = file->f_pos - 2;
1662 spin_lock(&configfs_dirent_lock);
1663 list_del(&cursor->s_sibling);
1664 p = sd->s_children.next;
1665 while (n && p != &sd->s_children) {
1666 struct configfs_dirent *next;
1667 next = list_entry(p, struct configfs_dirent,
1669 if (next->s_element)
1673 list_add_tail(&cursor->s_sibling, p);
1674 spin_unlock(&configfs_dirent_lock);
1677 mutex_unlock(&dentry->d_inode->i_mutex);
1681 const struct file_operations configfs_dir_operations = {
1682 .open = configfs_dir_open,
1683 .release = configfs_dir_close,
1684 .llseek = configfs_dir_lseek,
1685 .read = generic_read_dir,
1686 .readdir = configfs_readdir,
1689 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1692 struct config_group *group = &subsys->su_group;
1694 struct dentry *dentry;
1695 struct configfs_dirent *sd;
1697 err = configfs_pin_fs();
1701 if (!group->cg_item.ci_name)
1702 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1704 sd = configfs_sb->s_root->d_fsdata;
1705 link_group(to_config_group(sd->s_element), group);
1707 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1710 name.name = group->cg_item.ci_name;
1711 name.len = strlen(name.name);
1712 name.hash = full_name_hash(name.name, name.len);
1715 dentry = d_alloc(configfs_sb->s_root, &name);
1717 d_add(dentry, NULL);
1719 err = configfs_attach_group(sd->s_element, &group->cg_item,
1722 BUG_ON(dentry->d_inode);
1726 spin_lock(&configfs_dirent_lock);
1727 configfs_dir_set_ready(dentry->d_fsdata);
1728 spin_unlock(&configfs_dirent_lock);
1732 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1735 unlink_group(group);
1736 configfs_release_fs();
1742 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1744 struct config_group *group = &subsys->su_group;
1745 struct dentry *dentry = group->cg_item.ci_dentry;
1747 if (dentry->d_parent != configfs_sb->s_root) {
1748 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1752 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1754 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
1755 mutex_lock(&configfs_symlink_mutex);
1756 spin_lock(&configfs_dirent_lock);
1757 if (configfs_detach_prep(dentry, NULL)) {
1758 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1760 spin_unlock(&configfs_dirent_lock);
1761 mutex_unlock(&configfs_symlink_mutex);
1762 configfs_detach_group(&group->cg_item);
1763 dentry->d_inode->i_flags |= S_DEAD;
1765 mutex_unlock(&dentry->d_inode->i_mutex);
1769 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1773 unlink_group(group);
1774 configfs_release_fs();
1777 EXPORT_SYMBOL(configfs_register_subsystem);
1778 EXPORT_SYMBOL(configfs_unregister_subsystem);