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 BUG_ON(sd->s_dentry != dentry);
67 * We _must_ delete our dentries on last dput, as the chain-to-parent
68 * behavior is required to clear the parents of default_groups.
70 static int configfs_d_delete(struct dentry *dentry)
75 static const struct dentry_operations configfs_dentry_ops = {
76 .d_iput = configfs_d_iput,
77 /* simple_delete_dentry() isn't exported */
78 .d_delete = configfs_d_delete,
82 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
84 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * parent_sd,
87 struct configfs_dirent * sd;
89 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
91 return ERR_PTR(-ENOMEM);
93 atomic_set(&sd->s_count, 1);
94 INIT_LIST_HEAD(&sd->s_links);
95 INIT_LIST_HEAD(&sd->s_children);
96 sd->s_element = element;
97 spin_lock(&configfs_dirent_lock);
98 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
99 spin_unlock(&configfs_dirent_lock);
100 kmem_cache_free(configfs_dir_cachep, sd);
101 return ERR_PTR(-ENOENT);
103 list_add(&sd->s_sibling, &parent_sd->s_children);
104 spin_unlock(&configfs_dirent_lock);
111 * Return -EEXIST if there is already a configfs element with the same
112 * name for the same parent.
114 * called with parent inode's i_mutex held
116 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
117 const unsigned char *new)
119 struct configfs_dirent * sd;
121 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
123 const unsigned char *existing = configfs_get_name(sd);
124 if (strcmp(existing, new))
135 int configfs_make_dirent(struct configfs_dirent * parent_sd,
136 struct dentry * dentry, void * element,
137 umode_t mode, int type)
139 struct configfs_dirent * sd;
141 sd = configfs_new_dirent(parent_sd, element);
147 sd->s_dentry = dentry;
149 dentry->d_fsdata = configfs_get(sd);
150 dentry->d_op = &configfs_dentry_ops;
156 static int init_dir(struct inode * inode)
158 inode->i_op = &configfs_dir_inode_operations;
159 inode->i_fop = &configfs_dir_operations;
161 /* directory inodes start off with i_nlink == 2 (for "." entry) */
166 static int configfs_init_file(struct inode * inode)
168 inode->i_size = PAGE_SIZE;
169 inode->i_fop = &configfs_file_operations;
173 static int init_symlink(struct inode * inode)
175 inode->i_op = &configfs_symlink_inode_operations;
179 static int create_dir(struct config_item * k, struct dentry * p,
183 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
185 error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
187 error = configfs_make_dirent(p->d_fsdata, d, k, mode,
188 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
190 error = configfs_create(d, mode, init_dir);
192 inc_nlink(p->d_inode);
193 (d)->d_op = &configfs_dentry_ops;
195 struct configfs_dirent *sd = d->d_fsdata;
197 spin_lock(&configfs_dirent_lock);
198 list_del_init(&sd->s_sibling);
199 spin_unlock(&configfs_dirent_lock);
209 * configfs_create_dir - create a directory for an config_item.
210 * @item: config_itemwe're creating directory for.
211 * @dentry: config_item's dentry.
213 * Note: user-created entries won't be allowed under this new directory
214 * until it is validated by configfs_dir_set_ready()
217 static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
219 struct dentry * parent;
225 parent = item->ci_parent->ci_dentry;
226 else if (configfs_mount && configfs_mount->mnt_sb)
227 parent = configfs_mount->mnt_sb->s_root;
231 error = create_dir(item,parent,dentry);
233 item->ci_dentry = dentry;
238 * Allow userspace to create new entries under a new directory created with
239 * configfs_create_dir(), and under all of its chidlren directories recursively.
240 * @sd configfs_dirent of the new directory to validate
242 * Caller must hold configfs_dirent_lock.
244 static void configfs_dir_set_ready(struct configfs_dirent *sd)
246 struct configfs_dirent *child_sd;
248 sd->s_type &= ~CONFIGFS_USET_CREATING;
249 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
250 if (child_sd->s_type & CONFIGFS_USET_CREATING)
251 configfs_dir_set_ready(child_sd);
255 * Check that a directory does not belong to a directory hierarchy being
256 * attached and not validated yet.
257 * @sd configfs_dirent of the directory to check
259 * @return non-zero iff the directory was validated
261 * Note: takes configfs_dirent_lock, so the result may change from false to true
262 * in two consecutive calls, but never from true to false.
264 int configfs_dirent_is_ready(struct configfs_dirent *sd)
268 spin_lock(&configfs_dirent_lock);
269 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
270 spin_unlock(&configfs_dirent_lock);
275 int configfs_create_link(struct configfs_symlink *sl,
276 struct dentry *parent,
277 struct dentry *dentry)
280 umode_t mode = S_IFLNK | S_IRWXUGO;
282 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
285 err = configfs_create(dentry, mode, init_symlink);
287 dentry->d_op = &configfs_dentry_ops;
289 struct configfs_dirent *sd = dentry->d_fsdata;
291 spin_lock(&configfs_dirent_lock);
292 list_del_init(&sd->s_sibling);
293 spin_unlock(&configfs_dirent_lock);
301 static void remove_dir(struct dentry * d)
303 struct dentry * parent = dget(d->d_parent);
304 struct configfs_dirent * sd;
307 spin_lock(&configfs_dirent_lock);
308 list_del_init(&sd->s_sibling);
309 spin_unlock(&configfs_dirent_lock);
312 simple_rmdir(parent->d_inode,d);
314 pr_debug(" o %s removing done (%d)\n",d->d_name.name,
315 atomic_read(&d->d_count));
321 * configfs_remove_dir - remove an config_item's directory.
322 * @item: config_item we're removing.
324 * The only thing special about this is that we remove any files in
325 * the directory before we remove the directory, and we've inlined
326 * what used to be configfs_rmdir() below, instead of calling separately.
328 * Caller holds the mutex of the item's inode
331 static void configfs_remove_dir(struct config_item * item)
333 struct dentry * dentry = dget(item->ci_dentry);
340 * Drop reference from dget() on entrance.
346 /* attaches attribute's configfs_dirent to the dentry corresponding to the
349 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
351 struct configfs_attribute * attr = sd->s_element;
354 dentry->d_fsdata = configfs_get(sd);
355 sd->s_dentry = dentry;
356 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
363 dentry->d_op = &configfs_dentry_ops;
369 static struct dentry * configfs_lookup(struct inode *dir,
370 struct dentry *dentry,
371 struct nameidata *nd)
373 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
374 struct configfs_dirent * sd;
379 * Fake invisibility if dir belongs to a group/default groups hierarchy
382 * This forbids userspace to read/write attributes of items which may
383 * not complete their initialization, since the dentries of the
384 * attributes won't be instantiated.
387 if (!configfs_dirent_is_ready(parent_sd))
390 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
391 if (sd->s_type & CONFIGFS_NOT_PINNED) {
392 const unsigned char * name = configfs_get_name(sd);
394 if (strcmp(name, dentry->d_name.name))
398 err = configfs_attach_attr(sd, dentry);
405 * If it doesn't exist and it isn't a NOT_PINNED item,
406 * it must be negative.
408 return simple_lookup(dir, dentry, nd);
416 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
417 * attributes and are removed by rmdir(). We recurse, setting
418 * CONFIGFS_USET_DROPPING on all children that are candidates for
420 * If there is an error, the caller will reset the flags via
421 * configfs_detach_rollback().
423 static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
425 struct configfs_dirent *parent_sd = dentry->d_fsdata;
426 struct configfs_dirent *sd;
429 /* Mark that we're trying to drop the group */
430 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
433 if (!list_empty(&parent_sd->s_links))
437 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
438 if (!sd->s_element ||
439 (sd->s_type & CONFIGFS_NOT_PINNED))
441 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
442 /* Abort if racing with mkdir() */
443 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
445 *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
450 * Yup, recursive. If there's a problem, blame
451 * deep nesting of default_groups
453 ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
467 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
470 static void configfs_detach_rollback(struct dentry *dentry)
472 struct configfs_dirent *parent_sd = dentry->d_fsdata;
473 struct configfs_dirent *sd;
475 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
477 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
478 if (sd->s_type & CONFIGFS_USET_DEFAULT)
479 configfs_detach_rollback(sd->s_dentry);
482 static void detach_attrs(struct config_item * item)
484 struct dentry * dentry = dget(item->ci_dentry);
485 struct configfs_dirent * parent_sd;
486 struct configfs_dirent * sd, * tmp;
491 pr_debug("configfs %s: dropping attrs for dir\n",
492 dentry->d_name.name);
494 parent_sd = dentry->d_fsdata;
495 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
496 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
498 spin_lock(&configfs_dirent_lock);
499 list_del_init(&sd->s_sibling);
500 spin_unlock(&configfs_dirent_lock);
501 configfs_drop_dentry(sd, dentry);
506 * Drop reference from dget() on entrance.
511 static int populate_attrs(struct config_item *item)
513 struct config_item_type *t = item->ci_type;
514 struct configfs_attribute *attr;
521 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
522 if ((error = configfs_create_file(item, attr)))
533 static int configfs_attach_group(struct config_item *parent_item,
534 struct config_item *item,
535 struct dentry *dentry);
536 static void configfs_detach_group(struct config_item *item);
538 static void detach_groups(struct config_group *group)
540 struct dentry * dentry = dget(group->cg_item.ci_dentry);
541 struct dentry *child;
542 struct configfs_dirent *parent_sd;
543 struct configfs_dirent *sd, *tmp;
548 parent_sd = dentry->d_fsdata;
549 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
550 if (!sd->s_element ||
551 !(sd->s_type & CONFIGFS_USET_DEFAULT))
554 child = sd->s_dentry;
556 mutex_lock(&child->d_inode->i_mutex);
558 configfs_detach_group(sd->s_element);
559 child->d_inode->i_flags |= S_DEAD;
561 mutex_unlock(&child->d_inode->i_mutex);
568 * Drop reference from dget() on entrance.
574 * This fakes mkdir(2) on a default_groups[] entry. It
575 * creates a dentry, attachs it, and then does fixup
578 * We could, perhaps, tweak our parent's ->mkdir for a minute and
579 * try using vfs_mkdir. Just a thought.
581 static int create_default_group(struct config_group *parent_group,
582 struct config_group *group)
586 struct configfs_dirent *sd;
587 /* We trust the caller holds a reference to parent */
588 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
590 if (!group->cg_item.ci_name)
591 group->cg_item.ci_name = group->cg_item.ci_namebuf;
592 name.name = group->cg_item.ci_name;
593 name.len = strlen(name.name);
594 name.hash = full_name_hash(name.name, name.len);
597 child = d_alloc(parent, &name);
601 ret = configfs_attach_group(&parent_group->cg_item,
602 &group->cg_item, child);
604 sd = child->d_fsdata;
605 sd->s_type |= CONFIGFS_USET_DEFAULT;
615 static int populate_groups(struct config_group *group)
617 struct config_group *new_group;
621 if (group->default_groups) {
622 for (i = 0; group->default_groups[i]; i++) {
623 new_group = group->default_groups[i];
625 ret = create_default_group(group, new_group);
627 detach_groups(group);
637 * All of link_obj/unlink_obj/link_group/unlink_group require that
638 * subsys->su_mutex is held.
641 static void unlink_obj(struct config_item *item)
643 struct config_group *group;
645 group = item->ci_group;
647 list_del_init(&item->ci_entry);
649 item->ci_group = NULL;
650 item->ci_parent = NULL;
652 /* Drop the reference for ci_entry */
653 config_item_put(item);
655 /* Drop the reference for ci_parent */
656 config_group_put(group);
660 static void link_obj(struct config_item *parent_item, struct config_item *item)
663 * Parent seems redundant with group, but it makes certain
664 * traversals much nicer.
666 item->ci_parent = parent_item;
669 * We hold a reference on the parent for the child's ci_parent
672 item->ci_group = config_group_get(to_config_group(parent_item));
673 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
676 * We hold a reference on the child for ci_entry on the parent's
679 config_item_get(item);
682 static void unlink_group(struct config_group *group)
685 struct config_group *new_group;
687 if (group->default_groups) {
688 for (i = 0; group->default_groups[i]; i++) {
689 new_group = group->default_groups[i];
690 unlink_group(new_group);
694 group->cg_subsys = NULL;
695 unlink_obj(&group->cg_item);
698 static void link_group(struct config_group *parent_group, struct config_group *group)
701 struct config_group *new_group;
702 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
704 link_obj(&parent_group->cg_item, &group->cg_item);
706 if (parent_group->cg_subsys)
707 subsys = parent_group->cg_subsys;
708 else if (configfs_is_root(&parent_group->cg_item))
709 subsys = to_configfs_subsystem(group);
712 group->cg_subsys = subsys;
714 if (group->default_groups) {
715 for (i = 0; group->default_groups[i]; i++) {
716 new_group = group->default_groups[i];
717 link_group(group, new_group);
723 * The goal is that configfs_attach_item() (and
724 * configfs_attach_group()) can be called from either the VFS or this
725 * module. That is, they assume that the items have been created,
726 * the dentry allocated, and the dcache is all ready to go.
728 * If they fail, they must clean up after themselves as if they
729 * had never been called. The caller (VFS or local function) will
730 * handle cleaning up the dcache bits.
732 * configfs_detach_group() and configfs_detach_item() behave similarly on
733 * the way out. They assume that the proper semaphores are held, they
734 * clean up the configfs items, and they expect their callers will
735 * handle the dcache bits.
737 static int configfs_attach_item(struct config_item *parent_item,
738 struct config_item *item,
739 struct dentry *dentry)
743 ret = configfs_create_dir(item, dentry);
745 ret = populate_attrs(item);
748 * We are going to remove an inode and its dentry but
749 * the VFS may already have hit and used them. Thus,
750 * we must lock them as rmdir() would.
752 mutex_lock(&dentry->d_inode->i_mutex);
753 configfs_remove_dir(item);
754 dentry->d_inode->i_flags |= S_DEAD;
755 mutex_unlock(&dentry->d_inode->i_mutex);
763 /* Caller holds the mutex of the item's inode */
764 static void configfs_detach_item(struct config_item *item)
767 configfs_remove_dir(item);
770 static int configfs_attach_group(struct config_item *parent_item,
771 struct config_item *item,
772 struct dentry *dentry)
775 struct configfs_dirent *sd;
777 ret = configfs_attach_item(parent_item, item, dentry);
779 sd = dentry->d_fsdata;
780 sd->s_type |= CONFIGFS_USET_DIR;
783 * FYI, we're faking mkdir in populate_groups()
784 * We must lock the group's inode to avoid races with the VFS
785 * which can already hit the inode and try to add/remove entries
788 * We must also lock the inode to remove it safely in case of
789 * error, as rmdir() would.
791 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
792 ret = populate_groups(to_config_group(item));
794 configfs_detach_item(item);
795 dentry->d_inode->i_flags |= S_DEAD;
797 mutex_unlock(&dentry->d_inode->i_mutex);
805 /* Caller holds the mutex of the group's inode */
806 static void configfs_detach_group(struct config_item *item)
808 detach_groups(to_config_group(item));
809 configfs_detach_item(item);
813 * After the item has been detached from the filesystem view, we are
814 * ready to tear it out of the hierarchy. Notify the client before
815 * we do that so they can perform any cleanup that requires
816 * navigating the hierarchy. A client does not need to provide this
817 * callback. The subsystem semaphore MUST be held by the caller, and
818 * references must be valid for both items. It also assumes the
819 * caller has validated ci_type.
821 static void client_disconnect_notify(struct config_item *parent_item,
822 struct config_item *item)
824 struct config_item_type *type;
826 type = parent_item->ci_type;
829 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
830 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
835 * Drop the initial reference from make_item()/make_group()
836 * This function assumes that reference is held on item
837 * and that item holds a valid reference to the parent. Also, it
838 * assumes the caller has validated ci_type.
840 static void client_drop_item(struct config_item *parent_item,
841 struct config_item *item)
843 struct config_item_type *type;
845 type = parent_item->ci_type;
849 * If ->drop_item() exists, it is responsible for the
852 if (type->ct_group_ops && type->ct_group_ops->drop_item)
853 type->ct_group_ops->drop_item(to_config_group(parent_item),
856 config_item_put(item);
860 static void configfs_dump_one(struct configfs_dirent *sd, int level)
862 printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
864 #define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
865 type_print(CONFIGFS_ROOT);
866 type_print(CONFIGFS_DIR);
867 type_print(CONFIGFS_ITEM_ATTR);
868 type_print(CONFIGFS_ITEM_LINK);
869 type_print(CONFIGFS_USET_DIR);
870 type_print(CONFIGFS_USET_DEFAULT);
871 type_print(CONFIGFS_USET_DROPPING);
875 static int configfs_dump(struct configfs_dirent *sd, int level)
877 struct configfs_dirent *child_sd;
880 configfs_dump_one(sd, level);
882 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
885 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
886 ret = configfs_dump(child_sd, level + 2);
897 * configfs_depend_item() and configfs_undepend_item()
899 * WARNING: Do not call these from a configfs callback!
901 * This describes these functions and their helpers.
903 * Allow another kernel system to depend on a config_item. If this
904 * happens, the item cannot go away until the dependant can live without
905 * it. The idea is to give client modules as simple an interface as
906 * possible. When a system asks them to depend on an item, they just
907 * call configfs_depend_item(). If the item is live and the client
908 * driver is in good shape, we'll happily do the work for them.
910 * Why is the locking complex? Because configfs uses the VFS to handle
911 * all locking, but this function is called outside the normal
912 * VFS->configfs path. So it must take VFS locks to prevent the
913 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
914 * why you can't call these functions underneath configfs callbacks.
916 * Note, btw, that this can be called at *any* time, even when a configfs
917 * subsystem isn't registered, or when configfs is loading or unloading.
918 * Just like configfs_register_subsystem(). So we take the same
919 * precautions. We pin the filesystem. We lock each i_mutex _in_order_
920 * on our way down the tree. If we can find the target item in the
921 * configfs tree, it must be part of the subsystem tree as well, so we
922 * do not need the subsystem semaphore. Holding the i_mutex chain locks
923 * out mkdir() and rmdir(), who might be racing us.
927 * configfs_depend_prep()
929 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
930 * attributes. This is similar but not the same to configfs_detach_prep().
931 * Note that configfs_detach_prep() expects the parent to be locked when it
932 * is called, but we lock the parent *inside* configfs_depend_prep(). We
933 * do that so we can unlock it if we find nothing.
935 * Here we do a depth-first search of the dentry hierarchy looking for
936 * our object. We take i_mutex on each step of the way down. IT IS
937 * ESSENTIAL THAT i_mutex LOCKING IS ORDERED. If we come back up a branch,
938 * we'll drop the i_mutex.
940 * If the target is not found, -ENOENT is bubbled up and we have released
941 * all locks. If the target was found, the locks will be cleared by
942 * configfs_depend_rollback().
944 * This adds a requirement that all config_items be unique!
946 * This is recursive because the locking traversal is tricky. There isn't
947 * much on the stack, though, so folks that need this function - be careful
948 * about your stack! Patches will be accepted to make it iterative.
950 static int configfs_depend_prep(struct dentry *origin,
951 struct config_item *target)
953 struct configfs_dirent *child_sd, *sd = origin->d_fsdata;
956 BUG_ON(!origin || !sd);
958 /* Lock this guy on the way down */
959 mutex_lock(&sd->s_dentry->d_inode->i_mutex);
960 if (sd->s_element == target) /* Boo-yah */
963 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
964 if (child_sd->s_type & CONFIGFS_DIR) {
965 ret = configfs_depend_prep(child_sd->s_dentry,
968 goto out; /* Child path boo-yah */
972 /* We looped all our children and didn't find target */
973 mutex_unlock(&sd->s_dentry->d_inode->i_mutex);
981 * This is ONLY called if configfs_depend_prep() did its job. So we can
982 * trust the entire path from item back up to origin.
984 * We walk backwards from item, unlocking each i_mutex. We finish by
987 static void configfs_depend_rollback(struct dentry *origin,
988 struct config_item *item)
990 struct dentry *dentry = item->ci_dentry;
992 while (dentry != origin) {
993 mutex_unlock(&dentry->d_inode->i_mutex);
994 dentry = dentry->d_parent;
997 mutex_unlock(&origin->d_inode->i_mutex);
1000 int configfs_depend_item(struct configfs_subsystem *subsys,
1001 struct config_item *target)
1004 struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
1005 struct config_item *s_item = &subsys->su_group.cg_item;
1008 * Pin the configfs filesystem. This means we can safely access
1009 * the root of the configfs filesystem.
1011 ret = configfs_pin_fs();
1016 * Next, lock the root directory. We're going to check that the
1017 * subsystem is really registered, and so we need to lock out
1018 * configfs_[un]register_subsystem().
1020 mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1022 root_sd = configfs_sb->s_root->d_fsdata;
1024 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1025 if (p->s_type & CONFIGFS_DIR) {
1026 if (p->s_element == s_item) {
1038 /* Ok, now we can trust subsys/s_item */
1040 /* Scan the tree, locking i_mutex recursively, return 0 if found */
1041 ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1045 /* We hold all i_mutexes from the subsystem down to the target */
1046 p = target->ci_dentry->d_fsdata;
1047 p->s_dependent_count += 1;
1049 configfs_depend_rollback(subsys_sd->s_dentry, target);
1052 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1055 * If we succeeded, the fs is pinned via other methods. If not,
1056 * we're done with it anyway. So release_fs() is always right.
1058 configfs_release_fs();
1062 EXPORT_SYMBOL(configfs_depend_item);
1065 * Release the dependent linkage. This is much simpler than
1066 * configfs_depend_item() because we know that that the client driver is
1067 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1069 void configfs_undepend_item(struct configfs_subsystem *subsys,
1070 struct config_item *target)
1072 struct configfs_dirent *sd;
1075 * Since we can trust everything is pinned, we just need i_mutex
1078 mutex_lock(&target->ci_dentry->d_inode->i_mutex);
1080 sd = target->ci_dentry->d_fsdata;
1081 BUG_ON(sd->s_dependent_count < 1);
1083 sd->s_dependent_count -= 1;
1086 * After this unlock, we cannot trust the item to stay alive!
1087 * DO NOT REFERENCE item after this unlock.
1089 mutex_unlock(&target->ci_dentry->d_inode->i_mutex);
1091 EXPORT_SYMBOL(configfs_undepend_item);
1093 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1097 struct config_group *group = NULL;
1098 struct config_item *item = NULL;
1099 struct config_item *parent_item;
1100 struct configfs_subsystem *subsys;
1101 struct configfs_dirent *sd;
1102 struct config_item_type *type;
1103 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1106 if (dentry->d_parent == configfs_sb->s_root) {
1111 sd = dentry->d_parent->d_fsdata;
1114 * Fake invisibility if dir belongs to a group/default groups hierarchy
1117 if (!configfs_dirent_is_ready(sd)) {
1122 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1127 /* Get a working ref for the duration of this function */
1128 parent_item = configfs_get_config_item(dentry->d_parent);
1129 type = parent_item->ci_type;
1130 subsys = to_config_group(parent_item)->cg_subsys;
1133 if (!type || !type->ct_group_ops ||
1134 (!type->ct_group_ops->make_group &&
1135 !type->ct_group_ops->make_item)) {
1136 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1141 * The subsystem may belong to a different module than the item
1142 * being created. We don't want to safely pin the new item but
1143 * fail to pin the subsystem it sits under.
1145 if (!subsys->su_group.cg_item.ci_type) {
1149 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1150 if (!try_module_get(subsys_owner)) {
1155 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1158 goto out_subsys_put;
1161 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1163 mutex_lock(&subsys->su_mutex);
1164 if (type->ct_group_ops->make_group) {
1165 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1167 group = ERR_PTR(-ENOMEM);
1168 if (!IS_ERR(group)) {
1169 link_group(to_config_group(parent_item), group);
1170 item = &group->cg_item;
1172 ret = PTR_ERR(group);
1174 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1176 item = ERR_PTR(-ENOMEM);
1178 link_obj(parent_item, item);
1180 ret = PTR_ERR(item);
1182 mutex_unlock(&subsys->su_mutex);
1187 * If ret != 0, then link_obj() was never called.
1188 * There are no extra references to clean up.
1190 goto out_subsys_put;
1194 * link_obj() has been called (via link_group() for groups).
1195 * From here on out, errors must clean that up.
1198 type = item->ci_type;
1204 new_item_owner = type->ct_owner;
1205 if (!try_module_get(new_item_owner)) {
1211 * I hate doing it this way, but if there is
1212 * an error, module_put() probably should
1213 * happen after any cleanup.
1218 * Make racing rmdir() fail if it did not tag parent with
1219 * CONFIGFS_USET_DROPPING
1220 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1221 * fail and let rmdir() terminate correctly
1223 spin_lock(&configfs_dirent_lock);
1224 /* This will make configfs_detach_prep() fail */
1225 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1226 spin_unlock(&configfs_dirent_lock);
1229 ret = configfs_attach_group(parent_item, item, dentry);
1231 ret = configfs_attach_item(parent_item, item, dentry);
1233 spin_lock(&configfs_dirent_lock);
1234 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1236 configfs_dir_set_ready(dentry->d_fsdata);
1237 spin_unlock(&configfs_dirent_lock);
1241 /* Tear down everything we built up */
1242 mutex_lock(&subsys->su_mutex);
1244 client_disconnect_notify(parent_item, item);
1246 unlink_group(group);
1249 client_drop_item(parent_item, item);
1251 mutex_unlock(&subsys->su_mutex);
1254 module_put(new_item_owner);
1259 module_put(subsys_owner);
1263 * link_obj()/link_group() took a reference from child->parent,
1264 * so the parent is safely pinned. We can drop our working
1267 config_item_put(parent_item);
1273 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1275 struct config_item *parent_item;
1276 struct config_item *item;
1277 struct configfs_subsystem *subsys;
1278 struct configfs_dirent *sd;
1279 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1282 if (dentry->d_parent == configfs_sb->s_root)
1285 sd = dentry->d_fsdata;
1286 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1290 * Here's where we check for dependents. We're protected by
1293 if (sd->s_dependent_count)
1296 /* Get a working ref until we have the child */
1297 parent_item = configfs_get_config_item(dentry->d_parent);
1298 subsys = to_config_group(parent_item)->cg_subsys;
1301 if (!parent_item->ci_type) {
1302 config_item_put(parent_item);
1306 /* configfs_mkdir() shouldn't have allowed this */
1307 BUG_ON(!subsys->su_group.cg_item.ci_type);
1308 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1311 * Ensure that no racing symlink() will make detach_prep() fail while
1312 * the new link is temporarily attached
1315 struct mutex *wait_mutex;
1317 mutex_lock(&configfs_symlink_mutex);
1318 spin_lock(&configfs_dirent_lock);
1319 ret = configfs_detach_prep(dentry, &wait_mutex);
1321 configfs_detach_rollback(dentry);
1322 spin_unlock(&configfs_dirent_lock);
1323 mutex_unlock(&configfs_symlink_mutex);
1326 if (ret != -EAGAIN) {
1327 config_item_put(parent_item);
1331 /* Wait until the racing operation terminates */
1332 mutex_lock(wait_mutex);
1333 mutex_unlock(wait_mutex);
1335 } while (ret == -EAGAIN);
1337 /* Get a working ref for the duration of this function */
1338 item = configfs_get_config_item(dentry);
1340 /* Drop reference from above, item already holds one. */
1341 config_item_put(parent_item);
1344 dead_item_owner = item->ci_type->ct_owner;
1346 if (sd->s_type & CONFIGFS_USET_DIR) {
1347 configfs_detach_group(item);
1349 mutex_lock(&subsys->su_mutex);
1350 client_disconnect_notify(parent_item, item);
1351 unlink_group(to_config_group(item));
1353 configfs_detach_item(item);
1355 mutex_lock(&subsys->su_mutex);
1356 client_disconnect_notify(parent_item, item);
1360 client_drop_item(parent_item, item);
1361 mutex_unlock(&subsys->su_mutex);
1363 /* Drop our reference from above */
1364 config_item_put(item);
1366 module_put(dead_item_owner);
1367 module_put(subsys_owner);
1372 const struct inode_operations configfs_dir_inode_operations = {
1373 .mkdir = configfs_mkdir,
1374 .rmdir = configfs_rmdir,
1375 .symlink = configfs_symlink,
1376 .unlink = configfs_unlink,
1377 .lookup = configfs_lookup,
1378 .setattr = configfs_setattr,
1382 int configfs_rename_dir(struct config_item * item, const char *new_name)
1385 struct dentry * new_dentry, * parent;
1387 if (!strcmp(config_item_name(item), new_name))
1393 down_write(&configfs_rename_sem);
1394 parent = item->parent->dentry;
1396 mutex_lock(&parent->d_inode->i_mutex);
1398 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1399 if (!IS_ERR(new_dentry)) {
1400 if (!new_dentry->d_inode) {
1401 error = config_item_set_name(item, "%s", new_name);
1403 d_add(new_dentry, NULL);
1404 d_move(item->dentry, new_dentry);
1407 d_delete(new_dentry);
1412 mutex_unlock(&parent->d_inode->i_mutex);
1413 up_write(&configfs_rename_sem);
1419 static int configfs_dir_open(struct inode *inode, struct file *file)
1421 struct dentry * dentry = file->f_path.dentry;
1422 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1425 mutex_lock(&dentry->d_inode->i_mutex);
1427 * Fake invisibility if dir belongs to a group/default groups hierarchy
1431 if (configfs_dirent_is_ready(parent_sd)) {
1432 file->private_data = configfs_new_dirent(parent_sd, NULL);
1433 if (IS_ERR(file->private_data))
1434 err = PTR_ERR(file->private_data);
1438 mutex_unlock(&dentry->d_inode->i_mutex);
1443 static int configfs_dir_close(struct inode *inode, struct file *file)
1445 struct dentry * dentry = file->f_path.dentry;
1446 struct configfs_dirent * cursor = file->private_data;
1448 mutex_lock(&dentry->d_inode->i_mutex);
1449 spin_lock(&configfs_dirent_lock);
1450 list_del_init(&cursor->s_sibling);
1451 spin_unlock(&configfs_dirent_lock);
1452 mutex_unlock(&dentry->d_inode->i_mutex);
1454 release_configfs_dirent(cursor);
1459 /* Relationship between s_mode and the DT_xxx types */
1460 static inline unsigned char dt_type(struct configfs_dirent *sd)
1462 return (sd->s_mode >> 12) & 15;
1465 static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
1467 struct dentry *dentry = filp->f_path.dentry;
1468 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1469 struct configfs_dirent *cursor = filp->private_data;
1470 struct list_head *p, *q = &cursor->s_sibling;
1472 int i = filp->f_pos;
1476 ino = dentry->d_inode->i_ino;
1477 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1483 ino = parent_ino(dentry);
1484 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1490 if (filp->f_pos == 2) {
1491 spin_lock(&configfs_dirent_lock);
1492 list_move(q, &parent_sd->s_children);
1493 spin_unlock(&configfs_dirent_lock);
1495 for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
1496 struct configfs_dirent *next;
1500 next = list_entry(p, struct configfs_dirent,
1502 if (!next->s_element)
1505 name = configfs_get_name(next);
1508 ino = next->s_dentry->d_inode->i_ino;
1510 ino = iunique(configfs_sb, 2);
1512 if (filldir(dirent, name, len, filp->f_pos, ino,
1516 spin_lock(&configfs_dirent_lock);
1518 spin_unlock(&configfs_dirent_lock);
1526 static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
1528 struct dentry * dentry = file->f_path.dentry;
1530 mutex_lock(&dentry->d_inode->i_mutex);
1533 offset += file->f_pos;
1538 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
1541 if (offset != file->f_pos) {
1542 file->f_pos = offset;
1543 if (file->f_pos >= 2) {
1544 struct configfs_dirent *sd = dentry->d_fsdata;
1545 struct configfs_dirent *cursor = file->private_data;
1546 struct list_head *p;
1547 loff_t n = file->f_pos - 2;
1549 spin_lock(&configfs_dirent_lock);
1550 list_del(&cursor->s_sibling);
1551 p = sd->s_children.next;
1552 while (n && p != &sd->s_children) {
1553 struct configfs_dirent *next;
1554 next = list_entry(p, struct configfs_dirent,
1556 if (next->s_element)
1560 list_add_tail(&cursor->s_sibling, p);
1561 spin_unlock(&configfs_dirent_lock);
1564 mutex_unlock(&dentry->d_inode->i_mutex);
1568 const struct file_operations configfs_dir_operations = {
1569 .open = configfs_dir_open,
1570 .release = configfs_dir_close,
1571 .llseek = configfs_dir_lseek,
1572 .read = generic_read_dir,
1573 .readdir = configfs_readdir,
1576 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1579 struct config_group *group = &subsys->su_group;
1581 struct dentry *dentry;
1582 struct configfs_dirent *sd;
1584 err = configfs_pin_fs();
1588 if (!group->cg_item.ci_name)
1589 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1591 sd = configfs_sb->s_root->d_fsdata;
1592 link_group(to_config_group(sd->s_element), group);
1594 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1597 name.name = group->cg_item.ci_name;
1598 name.len = strlen(name.name);
1599 name.hash = full_name_hash(name.name, name.len);
1602 dentry = d_alloc(configfs_sb->s_root, &name);
1604 d_add(dentry, NULL);
1606 err = configfs_attach_group(sd->s_element, &group->cg_item,
1612 spin_lock(&configfs_dirent_lock);
1613 configfs_dir_set_ready(dentry->d_fsdata);
1614 spin_unlock(&configfs_dirent_lock);
1618 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1621 unlink_group(group);
1622 configfs_release_fs();
1628 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1630 struct config_group *group = &subsys->su_group;
1631 struct dentry *dentry = group->cg_item.ci_dentry;
1633 if (dentry->d_parent != configfs_sb->s_root) {
1634 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1638 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1640 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
1641 mutex_lock(&configfs_symlink_mutex);
1642 spin_lock(&configfs_dirent_lock);
1643 if (configfs_detach_prep(dentry, NULL)) {
1644 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1646 spin_unlock(&configfs_dirent_lock);
1647 mutex_unlock(&configfs_symlink_mutex);
1648 configfs_detach_group(&group->cg_item);
1649 dentry->d_inode->i_flags |= S_DEAD;
1650 mutex_unlock(&dentry->d_inode->i_mutex);
1654 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1658 unlink_group(group);
1659 configfs_release_fs();
1662 EXPORT_SYMBOL(configfs_register_subsystem);
1663 EXPORT_SYMBOL(configfs_unregister_subsystem);