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 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.
329 static void configfs_remove_dir(struct config_item * item)
331 struct dentry * dentry = dget(item->ci_dentry);
338 * Drop reference from dget() on entrance.
344 /* attaches attribute's configfs_dirent to the dentry corresponding to the
347 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
349 struct configfs_attribute * attr = sd->s_element;
352 dentry->d_fsdata = configfs_get(sd);
353 sd->s_dentry = dentry;
354 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
361 dentry->d_op = &configfs_dentry_ops;
367 static struct dentry * configfs_lookup(struct inode *dir,
368 struct dentry *dentry,
369 struct nameidata *nd)
371 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
372 struct configfs_dirent * sd;
377 * Fake invisibility if dir belongs to a group/default groups hierarchy
380 * This forbids userspace to read/write attributes of items which may
381 * not complete their initialization, since the dentries of the
382 * attributes won't be instantiated.
385 if (!configfs_dirent_is_ready(parent_sd))
388 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
389 if (sd->s_type & CONFIGFS_NOT_PINNED) {
390 const unsigned char * name = configfs_get_name(sd);
392 if (strcmp(name, dentry->d_name.name))
396 err = configfs_attach_attr(sd, dentry);
403 * If it doesn't exist and it isn't a NOT_PINNED item,
404 * it must be negative.
406 return simple_lookup(dir, dentry, nd);
414 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
415 * attributes and are removed by rmdir(). We recurse, setting
416 * CONFIGFS_USET_DROPPING on all children that are candidates for
418 * If there is an error, the caller will reset the flags via
419 * configfs_detach_rollback().
421 static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
423 struct configfs_dirent *parent_sd = dentry->d_fsdata;
424 struct configfs_dirent *sd;
427 /* Mark that we're trying to drop the group */
428 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
431 if (!list_empty(&parent_sd->s_links))
435 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
436 if (sd->s_type & CONFIGFS_NOT_PINNED)
438 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
439 /* Abort if racing with mkdir() */
440 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
442 *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
447 * Yup, recursive. If there's a problem, blame
448 * deep nesting of default_groups
450 ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
464 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
467 static void configfs_detach_rollback(struct dentry *dentry)
469 struct configfs_dirent *parent_sd = dentry->d_fsdata;
470 struct configfs_dirent *sd;
472 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
474 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
475 if (sd->s_type & CONFIGFS_USET_DEFAULT)
476 configfs_detach_rollback(sd->s_dentry);
479 static void detach_attrs(struct config_item * item)
481 struct dentry * dentry = dget(item->ci_dentry);
482 struct configfs_dirent * parent_sd;
483 struct configfs_dirent * sd, * tmp;
488 pr_debug("configfs %s: dropping attrs for dir\n",
489 dentry->d_name.name);
491 parent_sd = dentry->d_fsdata;
492 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
493 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
495 spin_lock(&configfs_dirent_lock);
496 list_del_init(&sd->s_sibling);
497 spin_unlock(&configfs_dirent_lock);
498 configfs_drop_dentry(sd, dentry);
503 * Drop reference from dget() on entrance.
508 static int populate_attrs(struct config_item *item)
510 struct config_item_type *t = item->ci_type;
511 struct configfs_attribute *attr;
518 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
519 if ((error = configfs_create_file(item, attr)))
530 static int configfs_attach_group(struct config_item *parent_item,
531 struct config_item *item,
532 struct dentry *dentry);
533 static void configfs_detach_group(struct config_item *item);
535 static void detach_groups(struct config_group *group)
537 struct dentry * dentry = dget(group->cg_item.ci_dentry);
538 struct dentry *child;
539 struct configfs_dirent *parent_sd;
540 struct configfs_dirent *sd, *tmp;
545 parent_sd = dentry->d_fsdata;
546 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
547 if (!sd->s_element ||
548 !(sd->s_type & CONFIGFS_USET_DEFAULT))
551 child = sd->s_dentry;
553 mutex_lock(&child->d_inode->i_mutex);
555 configfs_detach_group(sd->s_element);
556 child->d_inode->i_flags |= S_DEAD;
558 mutex_unlock(&child->d_inode->i_mutex);
565 * Drop reference from dget() on entrance.
571 * This fakes mkdir(2) on a default_groups[] entry. It
572 * creates a dentry, attachs it, and then does fixup
575 * We could, perhaps, tweak our parent's ->mkdir for a minute and
576 * try using vfs_mkdir. Just a thought.
578 static int create_default_group(struct config_group *parent_group,
579 struct config_group *group)
583 struct configfs_dirent *sd;
584 /* We trust the caller holds a reference to parent */
585 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
587 if (!group->cg_item.ci_name)
588 group->cg_item.ci_name = group->cg_item.ci_namebuf;
589 name.name = group->cg_item.ci_name;
590 name.len = strlen(name.name);
591 name.hash = full_name_hash(name.name, name.len);
594 child = d_alloc(parent, &name);
598 ret = configfs_attach_group(&parent_group->cg_item,
599 &group->cg_item, child);
601 sd = child->d_fsdata;
602 sd->s_type |= CONFIGFS_USET_DEFAULT;
612 static int populate_groups(struct config_group *group)
614 struct config_group *new_group;
615 struct dentry *dentry = group->cg_item.ci_dentry;
619 if (group->default_groups) {
621 * FYI, we're faking mkdir here
622 * I'm not sure we need this semaphore, as we're called
623 * from our parent's mkdir. That holds our parent's
624 * i_mutex, so afaik lookup cannot continue through our
625 * parent to find us, let alone mess with our tree.
626 * That said, taking our i_mutex is closer to mkdir
627 * emulation, and shouldn't hurt.
629 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
631 for (i = 0; group->default_groups[i]; i++) {
632 new_group = group->default_groups[i];
634 ret = create_default_group(group, new_group);
639 mutex_unlock(&dentry->d_inode->i_mutex);
643 detach_groups(group);
649 * All of link_obj/unlink_obj/link_group/unlink_group require that
650 * subsys->su_mutex is held.
653 static void unlink_obj(struct config_item *item)
655 struct config_group *group;
657 group = item->ci_group;
659 list_del_init(&item->ci_entry);
661 item->ci_group = NULL;
662 item->ci_parent = NULL;
664 /* Drop the reference for ci_entry */
665 config_item_put(item);
667 /* Drop the reference for ci_parent */
668 config_group_put(group);
672 static void link_obj(struct config_item *parent_item, struct config_item *item)
675 * Parent seems redundant with group, but it makes certain
676 * traversals much nicer.
678 item->ci_parent = parent_item;
681 * We hold a reference on the parent for the child's ci_parent
684 item->ci_group = config_group_get(to_config_group(parent_item));
685 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
688 * We hold a reference on the child for ci_entry on the parent's
691 config_item_get(item);
694 static void unlink_group(struct config_group *group)
697 struct config_group *new_group;
699 if (group->default_groups) {
700 for (i = 0; group->default_groups[i]; i++) {
701 new_group = group->default_groups[i];
702 unlink_group(new_group);
706 group->cg_subsys = NULL;
707 unlink_obj(&group->cg_item);
710 static void link_group(struct config_group *parent_group, struct config_group *group)
713 struct config_group *new_group;
714 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
716 link_obj(&parent_group->cg_item, &group->cg_item);
718 if (parent_group->cg_subsys)
719 subsys = parent_group->cg_subsys;
720 else if (configfs_is_root(&parent_group->cg_item))
721 subsys = to_configfs_subsystem(group);
724 group->cg_subsys = subsys;
726 if (group->default_groups) {
727 for (i = 0; group->default_groups[i]; i++) {
728 new_group = group->default_groups[i];
729 link_group(group, new_group);
735 * The goal is that configfs_attach_item() (and
736 * configfs_attach_group()) can be called from either the VFS or this
737 * module. That is, they assume that the items have been created,
738 * the dentry allocated, and the dcache is all ready to go.
740 * If they fail, they must clean up after themselves as if they
741 * had never been called. The caller (VFS or local function) will
742 * handle cleaning up the dcache bits.
744 * configfs_detach_group() and configfs_detach_item() behave similarly on
745 * the way out. They assume that the proper semaphores are held, they
746 * clean up the configfs items, and they expect their callers will
747 * handle the dcache bits.
749 static int configfs_attach_item(struct config_item *parent_item,
750 struct config_item *item,
751 struct dentry *dentry)
755 ret = configfs_create_dir(item, dentry);
757 ret = populate_attrs(item);
759 configfs_remove_dir(item);
767 static void configfs_detach_item(struct config_item *item)
770 configfs_remove_dir(item);
773 static int configfs_attach_group(struct config_item *parent_item,
774 struct config_item *item,
775 struct dentry *dentry)
778 struct configfs_dirent *sd;
780 ret = configfs_attach_item(parent_item, item, dentry);
782 sd = dentry->d_fsdata;
783 sd->s_type |= CONFIGFS_USET_DIR;
785 ret = populate_groups(to_config_group(item));
787 configfs_detach_item(item);
795 static void configfs_detach_group(struct config_item *item)
797 detach_groups(to_config_group(item));
798 configfs_detach_item(item);
802 * After the item has been detached from the filesystem view, we are
803 * ready to tear it out of the hierarchy. Notify the client before
804 * we do that so they can perform any cleanup that requires
805 * navigating the hierarchy. A client does not need to provide this
806 * callback. The subsystem semaphore MUST be held by the caller, and
807 * references must be valid for both items. It also assumes the
808 * caller has validated ci_type.
810 static void client_disconnect_notify(struct config_item *parent_item,
811 struct config_item *item)
813 struct config_item_type *type;
815 type = parent_item->ci_type;
818 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
819 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
824 * Drop the initial reference from make_item()/make_group()
825 * This function assumes that reference is held on item
826 * and that item holds a valid reference to the parent. Also, it
827 * assumes the caller has validated ci_type.
829 static void client_drop_item(struct config_item *parent_item,
830 struct config_item *item)
832 struct config_item_type *type;
834 type = parent_item->ci_type;
838 * If ->drop_item() exists, it is responsible for the
841 if (type->ct_group_ops && type->ct_group_ops->drop_item)
842 type->ct_group_ops->drop_item(to_config_group(parent_item),
845 config_item_put(item);
849 static void configfs_dump_one(struct configfs_dirent *sd, int level)
851 printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
853 #define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
854 type_print(CONFIGFS_ROOT);
855 type_print(CONFIGFS_DIR);
856 type_print(CONFIGFS_ITEM_ATTR);
857 type_print(CONFIGFS_ITEM_LINK);
858 type_print(CONFIGFS_USET_DIR);
859 type_print(CONFIGFS_USET_DEFAULT);
860 type_print(CONFIGFS_USET_DROPPING);
864 static int configfs_dump(struct configfs_dirent *sd, int level)
866 struct configfs_dirent *child_sd;
869 configfs_dump_one(sd, level);
871 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
874 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
875 ret = configfs_dump(child_sd, level + 2);
886 * configfs_depend_item() and configfs_undepend_item()
888 * WARNING: Do not call these from a configfs callback!
890 * This describes these functions and their helpers.
892 * Allow another kernel system to depend on a config_item. If this
893 * happens, the item cannot go away until the dependant can live without
894 * it. The idea is to give client modules as simple an interface as
895 * possible. When a system asks them to depend on an item, they just
896 * call configfs_depend_item(). If the item is live and the client
897 * driver is in good shape, we'll happily do the work for them.
899 * Why is the locking complex? Because configfs uses the VFS to handle
900 * all locking, but this function is called outside the normal
901 * VFS->configfs path. So it must take VFS locks to prevent the
902 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
903 * why you can't call these functions underneath configfs callbacks.
905 * Note, btw, that this can be called at *any* time, even when a configfs
906 * subsystem isn't registered, or when configfs is loading or unloading.
907 * Just like configfs_register_subsystem(). So we take the same
908 * precautions. We pin the filesystem. We lock each i_mutex _in_order_
909 * on our way down the tree. If we can find the target item in the
910 * configfs tree, it must be part of the subsystem tree as well, so we
911 * do not need the subsystem semaphore. Holding the i_mutex chain locks
912 * out mkdir() and rmdir(), who might be racing us.
916 * configfs_depend_prep()
918 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
919 * attributes. This is similar but not the same to configfs_detach_prep().
920 * Note that configfs_detach_prep() expects the parent to be locked when it
921 * is called, but we lock the parent *inside* configfs_depend_prep(). We
922 * do that so we can unlock it if we find nothing.
924 * Here we do a depth-first search of the dentry hierarchy looking for
925 * our object. We take i_mutex on each step of the way down. IT IS
926 * ESSENTIAL THAT i_mutex LOCKING IS ORDERED. If we come back up a branch,
927 * we'll drop the i_mutex.
929 * If the target is not found, -ENOENT is bubbled up and we have released
930 * all locks. If the target was found, the locks will be cleared by
931 * configfs_depend_rollback().
933 * This adds a requirement that all config_items be unique!
935 * This is recursive because the locking traversal is tricky. There isn't
936 * much on the stack, though, so folks that need this function - be careful
937 * about your stack! Patches will be accepted to make it iterative.
939 static int configfs_depend_prep(struct dentry *origin,
940 struct config_item *target)
942 struct configfs_dirent *child_sd, *sd = origin->d_fsdata;
945 BUG_ON(!origin || !sd);
947 /* Lock this guy on the way down */
948 mutex_lock(&sd->s_dentry->d_inode->i_mutex);
949 if (sd->s_element == target) /* Boo-yah */
952 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
953 if (child_sd->s_type & CONFIGFS_DIR) {
954 ret = configfs_depend_prep(child_sd->s_dentry,
957 goto out; /* Child path boo-yah */
961 /* We looped all our children and didn't find target */
962 mutex_unlock(&sd->s_dentry->d_inode->i_mutex);
970 * This is ONLY called if configfs_depend_prep() did its job. So we can
971 * trust the entire path from item back up to origin.
973 * We walk backwards from item, unlocking each i_mutex. We finish by
976 static void configfs_depend_rollback(struct dentry *origin,
977 struct config_item *item)
979 struct dentry *dentry = item->ci_dentry;
981 while (dentry != origin) {
982 mutex_unlock(&dentry->d_inode->i_mutex);
983 dentry = dentry->d_parent;
986 mutex_unlock(&origin->d_inode->i_mutex);
989 int configfs_depend_item(struct configfs_subsystem *subsys,
990 struct config_item *target)
993 struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
994 struct config_item *s_item = &subsys->su_group.cg_item;
997 * Pin the configfs filesystem. This means we can safely access
998 * the root of the configfs filesystem.
1000 ret = configfs_pin_fs();
1005 * Next, lock the root directory. We're going to check that the
1006 * subsystem is really registered, and so we need to lock out
1007 * configfs_[un]register_subsystem().
1009 mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1011 root_sd = configfs_sb->s_root->d_fsdata;
1013 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1014 if (p->s_type & CONFIGFS_DIR) {
1015 if (p->s_element == s_item) {
1027 /* Ok, now we can trust subsys/s_item */
1029 /* Scan the tree, locking i_mutex recursively, return 0 if found */
1030 ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1034 /* We hold all i_mutexes from the subsystem down to the target */
1035 p = target->ci_dentry->d_fsdata;
1036 p->s_dependent_count += 1;
1038 configfs_depend_rollback(subsys_sd->s_dentry, target);
1041 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1044 * If we succeeded, the fs is pinned via other methods. If not,
1045 * we're done with it anyway. So release_fs() is always right.
1047 configfs_release_fs();
1051 EXPORT_SYMBOL(configfs_depend_item);
1054 * Release the dependent linkage. This is much simpler than
1055 * configfs_depend_item() because we know that that the client driver is
1056 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1058 void configfs_undepend_item(struct configfs_subsystem *subsys,
1059 struct config_item *target)
1061 struct configfs_dirent *sd;
1064 * Since we can trust everything is pinned, we just need i_mutex
1067 mutex_lock(&target->ci_dentry->d_inode->i_mutex);
1069 sd = target->ci_dentry->d_fsdata;
1070 BUG_ON(sd->s_dependent_count < 1);
1072 sd->s_dependent_count -= 1;
1075 * After this unlock, we cannot trust the item to stay alive!
1076 * DO NOT REFERENCE item after this unlock.
1078 mutex_unlock(&target->ci_dentry->d_inode->i_mutex);
1080 EXPORT_SYMBOL(configfs_undepend_item);
1082 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1086 struct config_group *group = NULL;
1087 struct config_item *item = NULL;
1088 struct config_item *parent_item;
1089 struct configfs_subsystem *subsys;
1090 struct configfs_dirent *sd;
1091 struct config_item_type *type;
1092 struct module *owner = NULL;
1095 if (dentry->d_parent == configfs_sb->s_root) {
1100 sd = dentry->d_parent->d_fsdata;
1103 * Fake invisibility if dir belongs to a group/default groups hierarchy
1106 if (!configfs_dirent_is_ready(sd)) {
1111 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1116 /* Get a working ref for the duration of this function */
1117 parent_item = configfs_get_config_item(dentry->d_parent);
1118 type = parent_item->ci_type;
1119 subsys = to_config_group(parent_item)->cg_subsys;
1122 if (!type || !type->ct_group_ops ||
1123 (!type->ct_group_ops->make_group &&
1124 !type->ct_group_ops->make_item)) {
1125 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1129 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1135 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1137 mutex_lock(&subsys->su_mutex);
1138 if (type->ct_group_ops->make_group) {
1139 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1141 group = ERR_PTR(-ENOMEM);
1142 if (!IS_ERR(group)) {
1143 link_group(to_config_group(parent_item), group);
1144 item = &group->cg_item;
1146 ret = PTR_ERR(group);
1148 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1150 item = ERR_PTR(-ENOMEM);
1152 link_obj(parent_item, item);
1154 ret = PTR_ERR(item);
1156 mutex_unlock(&subsys->su_mutex);
1161 * If ret != 0, then link_obj() was never called.
1162 * There are no extra references to clean up.
1168 * link_obj() has been called (via link_group() for groups).
1169 * From here on out, errors must clean that up.
1172 type = item->ci_type;
1178 owner = type->ct_owner;
1179 if (!try_module_get(owner)) {
1185 * I hate doing it this way, but if there is
1186 * an error, module_put() probably should
1187 * happen after any cleanup.
1192 * Make racing rmdir() fail if it did not tag parent with
1193 * CONFIGFS_USET_DROPPING
1194 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1195 * fail and let rmdir() terminate correctly
1197 spin_lock(&configfs_dirent_lock);
1198 /* This will make configfs_detach_prep() fail */
1199 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1200 spin_unlock(&configfs_dirent_lock);
1203 ret = configfs_attach_group(parent_item, item, dentry);
1205 ret = configfs_attach_item(parent_item, item, dentry);
1207 spin_lock(&configfs_dirent_lock);
1208 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1210 configfs_dir_set_ready(dentry->d_fsdata);
1211 spin_unlock(&configfs_dirent_lock);
1215 /* Tear down everything we built up */
1216 mutex_lock(&subsys->su_mutex);
1218 client_disconnect_notify(parent_item, item);
1220 unlink_group(group);
1223 client_drop_item(parent_item, item);
1225 mutex_unlock(&subsys->su_mutex);
1233 * link_obj()/link_group() took a reference from child->parent,
1234 * so the parent is safely pinned. We can drop our working
1237 config_item_put(parent_item);
1243 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1245 struct config_item *parent_item;
1246 struct config_item *item;
1247 struct configfs_subsystem *subsys;
1248 struct configfs_dirent *sd;
1249 struct module *owner = NULL;
1252 if (dentry->d_parent == configfs_sb->s_root)
1255 sd = dentry->d_fsdata;
1256 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1260 * Here's where we check for dependents. We're protected by
1263 if (sd->s_dependent_count)
1266 /* Get a working ref until we have the child */
1267 parent_item = configfs_get_config_item(dentry->d_parent);
1268 subsys = to_config_group(parent_item)->cg_subsys;
1271 if (!parent_item->ci_type) {
1272 config_item_put(parent_item);
1277 * Ensure that no racing symlink() will make detach_prep() fail while
1278 * the new link is temporarily attached
1280 mutex_lock(&configfs_symlink_mutex);
1281 spin_lock(&configfs_dirent_lock);
1283 struct mutex *wait_mutex;
1285 ret = configfs_detach_prep(dentry, &wait_mutex);
1287 configfs_detach_rollback(dentry);
1288 spin_unlock(&configfs_dirent_lock);
1289 mutex_unlock(&configfs_symlink_mutex);
1290 if (ret != -EAGAIN) {
1291 config_item_put(parent_item);
1295 /* Wait until the racing operation terminates */
1296 mutex_lock(wait_mutex);
1297 mutex_unlock(wait_mutex);
1299 mutex_lock(&configfs_symlink_mutex);
1300 spin_lock(&configfs_dirent_lock);
1302 } while (ret == -EAGAIN);
1303 spin_unlock(&configfs_dirent_lock);
1304 mutex_unlock(&configfs_symlink_mutex);
1306 /* Get a working ref for the duration of this function */
1307 item = configfs_get_config_item(dentry);
1309 /* Drop reference from above, item already holds one. */
1310 config_item_put(parent_item);
1313 owner = item->ci_type->ct_owner;
1315 if (sd->s_type & CONFIGFS_USET_DIR) {
1316 configfs_detach_group(item);
1318 mutex_lock(&subsys->su_mutex);
1319 client_disconnect_notify(parent_item, item);
1320 unlink_group(to_config_group(item));
1322 configfs_detach_item(item);
1324 mutex_lock(&subsys->su_mutex);
1325 client_disconnect_notify(parent_item, item);
1329 client_drop_item(parent_item, item);
1330 mutex_unlock(&subsys->su_mutex);
1332 /* Drop our reference from above */
1333 config_item_put(item);
1340 const struct inode_operations configfs_dir_inode_operations = {
1341 .mkdir = configfs_mkdir,
1342 .rmdir = configfs_rmdir,
1343 .symlink = configfs_symlink,
1344 .unlink = configfs_unlink,
1345 .lookup = configfs_lookup,
1346 .setattr = configfs_setattr,
1350 int configfs_rename_dir(struct config_item * item, const char *new_name)
1353 struct dentry * new_dentry, * parent;
1355 if (!strcmp(config_item_name(item), new_name))
1361 down_write(&configfs_rename_sem);
1362 parent = item->parent->dentry;
1364 mutex_lock(&parent->d_inode->i_mutex);
1366 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1367 if (!IS_ERR(new_dentry)) {
1368 if (!new_dentry->d_inode) {
1369 error = config_item_set_name(item, "%s", new_name);
1371 d_add(new_dentry, NULL);
1372 d_move(item->dentry, new_dentry);
1375 d_delete(new_dentry);
1380 mutex_unlock(&parent->d_inode->i_mutex);
1381 up_write(&configfs_rename_sem);
1387 static int configfs_dir_open(struct inode *inode, struct file *file)
1389 struct dentry * dentry = file->f_path.dentry;
1390 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1393 mutex_lock(&dentry->d_inode->i_mutex);
1395 * Fake invisibility if dir belongs to a group/default groups hierarchy
1399 if (configfs_dirent_is_ready(parent_sd)) {
1400 file->private_data = configfs_new_dirent(parent_sd, NULL);
1401 if (IS_ERR(file->private_data))
1402 err = PTR_ERR(file->private_data);
1406 mutex_unlock(&dentry->d_inode->i_mutex);
1411 static int configfs_dir_close(struct inode *inode, struct file *file)
1413 struct dentry * dentry = file->f_path.dentry;
1414 struct configfs_dirent * cursor = file->private_data;
1416 mutex_lock(&dentry->d_inode->i_mutex);
1417 spin_lock(&configfs_dirent_lock);
1418 list_del_init(&cursor->s_sibling);
1419 spin_unlock(&configfs_dirent_lock);
1420 mutex_unlock(&dentry->d_inode->i_mutex);
1422 release_configfs_dirent(cursor);
1427 /* Relationship between s_mode and the DT_xxx types */
1428 static inline unsigned char dt_type(struct configfs_dirent *sd)
1430 return (sd->s_mode >> 12) & 15;
1433 static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
1435 struct dentry *dentry = filp->f_path.dentry;
1436 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1437 struct configfs_dirent *cursor = filp->private_data;
1438 struct list_head *p, *q = &cursor->s_sibling;
1440 int i = filp->f_pos;
1444 ino = dentry->d_inode->i_ino;
1445 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1451 ino = parent_ino(dentry);
1452 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1458 if (filp->f_pos == 2) {
1459 spin_lock(&configfs_dirent_lock);
1460 list_move(q, &parent_sd->s_children);
1461 spin_unlock(&configfs_dirent_lock);
1463 for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
1464 struct configfs_dirent *next;
1468 next = list_entry(p, struct configfs_dirent,
1470 if (!next->s_element)
1473 name = configfs_get_name(next);
1476 ino = next->s_dentry->d_inode->i_ino;
1478 ino = iunique(configfs_sb, 2);
1480 if (filldir(dirent, name, len, filp->f_pos, ino,
1484 spin_lock(&configfs_dirent_lock);
1486 spin_unlock(&configfs_dirent_lock);
1494 static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
1496 struct dentry * dentry = file->f_path.dentry;
1498 mutex_lock(&dentry->d_inode->i_mutex);
1501 offset += file->f_pos;
1506 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
1509 if (offset != file->f_pos) {
1510 file->f_pos = offset;
1511 if (file->f_pos >= 2) {
1512 struct configfs_dirent *sd = dentry->d_fsdata;
1513 struct configfs_dirent *cursor = file->private_data;
1514 struct list_head *p;
1515 loff_t n = file->f_pos - 2;
1517 spin_lock(&configfs_dirent_lock);
1518 list_del(&cursor->s_sibling);
1519 p = sd->s_children.next;
1520 while (n && p != &sd->s_children) {
1521 struct configfs_dirent *next;
1522 next = list_entry(p, struct configfs_dirent,
1524 if (next->s_element)
1528 list_add_tail(&cursor->s_sibling, p);
1529 spin_unlock(&configfs_dirent_lock);
1532 mutex_unlock(&dentry->d_inode->i_mutex);
1536 const struct file_operations configfs_dir_operations = {
1537 .open = configfs_dir_open,
1538 .release = configfs_dir_close,
1539 .llseek = configfs_dir_lseek,
1540 .read = generic_read_dir,
1541 .readdir = configfs_readdir,
1544 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1547 struct config_group *group = &subsys->su_group;
1549 struct dentry *dentry;
1550 struct configfs_dirent *sd;
1552 err = configfs_pin_fs();
1556 if (!group->cg_item.ci_name)
1557 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1559 sd = configfs_sb->s_root->d_fsdata;
1560 link_group(to_config_group(sd->s_element), group);
1562 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1565 name.name = group->cg_item.ci_name;
1566 name.len = strlen(name.name);
1567 name.hash = full_name_hash(name.name, name.len);
1570 dentry = d_alloc(configfs_sb->s_root, &name);
1572 d_add(dentry, NULL);
1574 err = configfs_attach_group(sd->s_element, &group->cg_item,
1580 spin_lock(&configfs_dirent_lock);
1581 configfs_dir_set_ready(dentry->d_fsdata);
1582 spin_unlock(&configfs_dirent_lock);
1586 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1589 unlink_group(group);
1590 configfs_release_fs();
1596 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1598 struct config_group *group = &subsys->su_group;
1599 struct dentry *dentry = group->cg_item.ci_dentry;
1601 if (dentry->d_parent != configfs_sb->s_root) {
1602 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1606 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1608 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
1609 mutex_lock(&configfs_symlink_mutex);
1610 spin_lock(&configfs_dirent_lock);
1611 if (configfs_detach_prep(dentry, NULL)) {
1612 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1614 spin_unlock(&configfs_dirent_lock);
1615 mutex_unlock(&configfs_symlink_mutex);
1616 configfs_detach_group(&group->cg_item);
1617 dentry->d_inode->i_flags |= S_DEAD;
1618 mutex_unlock(&dentry->d_inode->i_mutex);
1622 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1626 unlink_group(group);
1627 configfs_release_fs();
1630 EXPORT_SYMBOL(configfs_register_subsystem);
1631 EXPORT_SYMBOL(configfs_unregister_subsystem);