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);
60 /* Coordinate with configfs_readdir */
61 spin_lock(&configfs_dirent_lock);
63 spin_unlock(&configfs_dirent_lock);
69 const struct dentry_operations configfs_dentry_ops = {
70 .d_iput = configfs_d_iput,
71 .d_delete = always_delete_dentry,
77 * Helpers to make lockdep happy with our recursive locking of default groups'
78 * inodes (see configfs_attach_group() and configfs_detach_group()).
79 * We put default groups i_mutexes in separate classes according to their depth
80 * from the youngest non-default group ancestor.
82 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
83 * groups A/B and A/C will have their inode's mutex in class
84 * default_group_class[0], and default group A/C/D will be in
85 * default_group_class[1].
87 * The lock classes are declared and assigned in inode.c, according to the
89 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
90 * default groups, and reset to -1 when all default groups are attached. During
91 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
92 * inode's mutex is set to default_group_class[s_depth - 1].
95 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
100 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
101 struct configfs_dirent *sd)
103 int parent_depth = parent_sd->s_depth;
105 if (parent_depth >= 0)
106 sd->s_depth = parent_depth + 1;
110 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
113 * item's i_mutex class is already setup, so s_depth is now only
114 * used to set new sub-directories s_depth, which is always done
115 * with item's i_mutex locked.
118 * sd->s_depth == -1 iff we are a non default group.
119 * else (we are a default group) sd->s_depth > 0 (see
122 if (sd->s_depth == -1)
124 * We are a non default group and we are going to create
131 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
133 /* We will not create default groups anymore. */
137 #else /* CONFIG_LOCKDEP */
139 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
143 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
144 struct configfs_dirent *sd)
149 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
154 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
158 #endif /* CONFIG_LOCKDEP */
161 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
163 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
164 void *element, int type)
166 struct configfs_dirent * sd;
168 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
170 return ERR_PTR(-ENOMEM);
172 atomic_set(&sd->s_count, 1);
173 INIT_LIST_HEAD(&sd->s_links);
174 INIT_LIST_HEAD(&sd->s_children);
175 sd->s_element = element;
177 configfs_init_dirent_depth(sd);
178 spin_lock(&configfs_dirent_lock);
179 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
180 spin_unlock(&configfs_dirent_lock);
181 kmem_cache_free(configfs_dir_cachep, sd);
182 return ERR_PTR(-ENOENT);
184 list_add(&sd->s_sibling, &parent_sd->s_children);
185 spin_unlock(&configfs_dirent_lock);
192 * Return -EEXIST if there is already a configfs element with the same
193 * name for the same parent.
195 * called with parent inode's i_mutex held
197 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
198 const unsigned char *new)
200 struct configfs_dirent * sd;
202 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
204 const unsigned char *existing = configfs_get_name(sd);
205 if (strcmp(existing, new))
216 int configfs_make_dirent(struct configfs_dirent * parent_sd,
217 struct dentry * dentry, void * element,
218 umode_t mode, int type)
220 struct configfs_dirent * sd;
222 sd = configfs_new_dirent(parent_sd, element, type);
227 sd->s_dentry = dentry;
229 dentry->d_fsdata = configfs_get(sd);
234 static int init_dir(struct inode * inode)
236 inode->i_op = &configfs_dir_inode_operations;
237 inode->i_fop = &configfs_dir_operations;
239 /* directory inodes start off with i_nlink == 2 (for "." entry) */
244 static int configfs_init_file(struct inode * inode)
246 inode->i_size = PAGE_SIZE;
247 inode->i_fop = &configfs_file_operations;
251 static int init_symlink(struct inode * inode)
253 inode->i_op = &configfs_symlink_inode_operations;
257 static int create_dir(struct config_item *k, struct dentry *d)
260 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
261 struct dentry *p = d->d_parent;
265 error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
267 error = configfs_make_dirent(p->d_fsdata, d, k, mode,
268 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
270 configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
271 error = configfs_create(d, mode, init_dir);
273 inc_nlink(p->d_inode);
275 struct configfs_dirent *sd = d->d_fsdata;
277 spin_lock(&configfs_dirent_lock);
278 list_del_init(&sd->s_sibling);
279 spin_unlock(&configfs_dirent_lock);
289 * configfs_create_dir - create a directory for an config_item.
290 * @item: config_itemwe're creating directory for.
291 * @dentry: config_item's dentry.
293 * Note: user-created entries won't be allowed under this new directory
294 * until it is validated by configfs_dir_set_ready()
297 static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
299 int error = create_dir(item, dentry);
301 item->ci_dentry = dentry;
306 * Allow userspace to create new entries under a new directory created with
307 * configfs_create_dir(), and under all of its chidlren directories recursively.
308 * @sd configfs_dirent of the new directory to validate
310 * Caller must hold configfs_dirent_lock.
312 static void configfs_dir_set_ready(struct configfs_dirent *sd)
314 struct configfs_dirent *child_sd;
316 sd->s_type &= ~CONFIGFS_USET_CREATING;
317 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
318 if (child_sd->s_type & CONFIGFS_USET_CREATING)
319 configfs_dir_set_ready(child_sd);
323 * Check that a directory does not belong to a directory hierarchy being
324 * attached and not validated yet.
325 * @sd configfs_dirent of the directory to check
327 * @return non-zero iff the directory was validated
329 * Note: takes configfs_dirent_lock, so the result may change from false to true
330 * in two consecutive calls, but never from true to false.
332 int configfs_dirent_is_ready(struct configfs_dirent *sd)
336 spin_lock(&configfs_dirent_lock);
337 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
338 spin_unlock(&configfs_dirent_lock);
343 int configfs_create_link(struct configfs_symlink *sl,
344 struct dentry *parent,
345 struct dentry *dentry)
348 umode_t mode = S_IFLNK | S_IRWXUGO;
350 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
353 err = configfs_create(dentry, mode, init_symlink);
355 struct configfs_dirent *sd = dentry->d_fsdata;
357 spin_lock(&configfs_dirent_lock);
358 list_del_init(&sd->s_sibling);
359 spin_unlock(&configfs_dirent_lock);
367 static void remove_dir(struct dentry * d)
369 struct dentry * parent = dget(d->d_parent);
370 struct configfs_dirent * sd;
373 spin_lock(&configfs_dirent_lock);
374 list_del_init(&sd->s_sibling);
375 spin_unlock(&configfs_dirent_lock);
378 simple_rmdir(parent->d_inode,d);
380 pr_debug(" o %s removing done (%d)\n",d->d_name.name, d_count(d));
386 * configfs_remove_dir - remove an config_item's directory.
387 * @item: config_item we're removing.
389 * The only thing special about this is that we remove any files in
390 * the directory before we remove the directory, and we've inlined
391 * what used to be configfs_rmdir() below, instead of calling separately.
393 * Caller holds the mutex of the item's inode
396 static void configfs_remove_dir(struct config_item * item)
398 struct dentry * dentry = dget(item->ci_dentry);
405 * Drop reference from dget() on entrance.
411 /* attaches attribute's configfs_dirent to the dentry corresponding to the
414 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
416 struct configfs_attribute * attr = sd->s_element;
419 dentry->d_fsdata = configfs_get(sd);
420 sd->s_dentry = dentry;
421 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
433 static struct dentry * configfs_lookup(struct inode *dir,
434 struct dentry *dentry,
437 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
438 struct configfs_dirent * sd;
443 * Fake invisibility if dir belongs to a group/default groups hierarchy
446 * This forbids userspace to read/write attributes of items which may
447 * not complete their initialization, since the dentries of the
448 * attributes won't be instantiated.
451 if (!configfs_dirent_is_ready(parent_sd))
454 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
455 if (sd->s_type & CONFIGFS_NOT_PINNED) {
456 const unsigned char * name = configfs_get_name(sd);
458 if (strcmp(name, dentry->d_name.name))
462 err = configfs_attach_attr(sd, dentry);
469 * If it doesn't exist and it isn't a NOT_PINNED item,
470 * it must be negative.
472 if (dentry->d_name.len > NAME_MAX)
473 return ERR_PTR(-ENAMETOOLONG);
483 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
484 * attributes and are removed by rmdir(). We recurse, setting
485 * CONFIGFS_USET_DROPPING on all children that are candidates for
487 * If there is an error, the caller will reset the flags via
488 * configfs_detach_rollback().
490 static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
492 struct configfs_dirent *parent_sd = dentry->d_fsdata;
493 struct configfs_dirent *sd;
496 /* Mark that we're trying to drop the group */
497 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
500 if (!list_empty(&parent_sd->s_links))
504 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
505 if (!sd->s_element ||
506 (sd->s_type & CONFIGFS_NOT_PINNED))
508 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
509 /* Abort if racing with mkdir() */
510 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
512 *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
517 * Yup, recursive. If there's a problem, blame
518 * deep nesting of default_groups
520 ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
534 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
537 static void configfs_detach_rollback(struct dentry *dentry)
539 struct configfs_dirent *parent_sd = dentry->d_fsdata;
540 struct configfs_dirent *sd;
542 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
544 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
545 if (sd->s_type & CONFIGFS_USET_DEFAULT)
546 configfs_detach_rollback(sd->s_dentry);
549 static void detach_attrs(struct config_item * item)
551 struct dentry * dentry = dget(item->ci_dentry);
552 struct configfs_dirent * parent_sd;
553 struct configfs_dirent * sd, * tmp;
558 pr_debug("configfs %s: dropping attrs for dir\n",
559 dentry->d_name.name);
561 parent_sd = dentry->d_fsdata;
562 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
563 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
565 spin_lock(&configfs_dirent_lock);
566 list_del_init(&sd->s_sibling);
567 spin_unlock(&configfs_dirent_lock);
568 configfs_drop_dentry(sd, dentry);
573 * Drop reference from dget() on entrance.
578 static int populate_attrs(struct config_item *item)
580 struct config_item_type *t = item->ci_type;
581 struct configfs_attribute *attr;
588 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
589 if ((error = configfs_create_file(item, attr)))
600 static int configfs_attach_group(struct config_item *parent_item,
601 struct config_item *item,
602 struct dentry *dentry);
603 static void configfs_detach_group(struct config_item *item);
605 static void detach_groups(struct config_group *group)
607 struct dentry * dentry = dget(group->cg_item.ci_dentry);
608 struct dentry *child;
609 struct configfs_dirent *parent_sd;
610 struct configfs_dirent *sd, *tmp;
615 parent_sd = dentry->d_fsdata;
616 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
617 if (!sd->s_element ||
618 !(sd->s_type & CONFIGFS_USET_DEFAULT))
621 child = sd->s_dentry;
623 mutex_lock(&child->d_inode->i_mutex);
625 configfs_detach_group(sd->s_element);
626 child->d_inode->i_flags |= S_DEAD;
629 mutex_unlock(&child->d_inode->i_mutex);
636 * Drop reference from dget() on entrance.
642 * This fakes mkdir(2) on a default_groups[] entry. It
643 * creates a dentry, attachs it, and then does fixup
646 * We could, perhaps, tweak our parent's ->mkdir for a minute and
647 * try using vfs_mkdir. Just a thought.
649 static int create_default_group(struct config_group *parent_group,
650 struct config_group *group)
653 struct configfs_dirent *sd;
654 /* We trust the caller holds a reference to parent */
655 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
657 if (!group->cg_item.ci_name)
658 group->cg_item.ci_name = group->cg_item.ci_namebuf;
661 child = d_alloc_name(parent, group->cg_item.ci_name);
665 ret = configfs_attach_group(&parent_group->cg_item,
666 &group->cg_item, child);
668 sd = child->d_fsdata;
669 sd->s_type |= CONFIGFS_USET_DEFAULT;
671 BUG_ON(child->d_inode);
680 static int populate_groups(struct config_group *group)
682 struct config_group *new_group;
686 if (group->default_groups) {
687 for (i = 0; group->default_groups[i]; i++) {
688 new_group = group->default_groups[i];
690 ret = create_default_group(group, new_group);
692 detach_groups(group);
702 * All of link_obj/unlink_obj/link_group/unlink_group require that
703 * subsys->su_mutex is held.
706 static void unlink_obj(struct config_item *item)
708 struct config_group *group;
710 group = item->ci_group;
712 list_del_init(&item->ci_entry);
714 item->ci_group = NULL;
715 item->ci_parent = NULL;
717 /* Drop the reference for ci_entry */
718 config_item_put(item);
720 /* Drop the reference for ci_parent */
721 config_group_put(group);
725 static void link_obj(struct config_item *parent_item, struct config_item *item)
728 * Parent seems redundant with group, but it makes certain
729 * traversals much nicer.
731 item->ci_parent = parent_item;
734 * We hold a reference on the parent for the child's ci_parent
737 item->ci_group = config_group_get(to_config_group(parent_item));
738 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
741 * We hold a reference on the child for ci_entry on the parent's
744 config_item_get(item);
747 static void unlink_group(struct config_group *group)
750 struct config_group *new_group;
752 if (group->default_groups) {
753 for (i = 0; group->default_groups[i]; i++) {
754 new_group = group->default_groups[i];
755 unlink_group(new_group);
759 group->cg_subsys = NULL;
760 unlink_obj(&group->cg_item);
763 static void link_group(struct config_group *parent_group, struct config_group *group)
766 struct config_group *new_group;
767 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
769 link_obj(&parent_group->cg_item, &group->cg_item);
771 if (parent_group->cg_subsys)
772 subsys = parent_group->cg_subsys;
773 else if (configfs_is_root(&parent_group->cg_item))
774 subsys = to_configfs_subsystem(group);
777 group->cg_subsys = subsys;
779 if (group->default_groups) {
780 for (i = 0; group->default_groups[i]; i++) {
781 new_group = group->default_groups[i];
782 link_group(group, new_group);
788 * The goal is that configfs_attach_item() (and
789 * configfs_attach_group()) can be called from either the VFS or this
790 * module. That is, they assume that the items have been created,
791 * the dentry allocated, and the dcache is all ready to go.
793 * If they fail, they must clean up after themselves as if they
794 * had never been called. The caller (VFS or local function) will
795 * handle cleaning up the dcache bits.
797 * configfs_detach_group() and configfs_detach_item() behave similarly on
798 * the way out. They assume that the proper semaphores are held, they
799 * clean up the configfs items, and they expect their callers will
800 * handle the dcache bits.
802 static int configfs_attach_item(struct config_item *parent_item,
803 struct config_item *item,
804 struct dentry *dentry)
808 ret = configfs_create_dir(item, dentry);
810 ret = populate_attrs(item);
813 * We are going to remove an inode and its dentry but
814 * the VFS may already have hit and used them. Thus,
815 * we must lock them as rmdir() would.
817 mutex_lock(&dentry->d_inode->i_mutex);
818 configfs_remove_dir(item);
819 dentry->d_inode->i_flags |= S_DEAD;
821 mutex_unlock(&dentry->d_inode->i_mutex);
829 /* Caller holds the mutex of the item's inode */
830 static void configfs_detach_item(struct config_item *item)
833 configfs_remove_dir(item);
836 static int configfs_attach_group(struct config_item *parent_item,
837 struct config_item *item,
838 struct dentry *dentry)
841 struct configfs_dirent *sd;
843 ret = configfs_attach_item(parent_item, item, dentry);
845 sd = dentry->d_fsdata;
846 sd->s_type |= CONFIGFS_USET_DIR;
849 * FYI, we're faking mkdir in populate_groups()
850 * We must lock the group's inode to avoid races with the VFS
851 * which can already hit the inode and try to add/remove entries
854 * We must also lock the inode to remove it safely in case of
855 * error, as rmdir() would.
857 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
858 configfs_adjust_dir_dirent_depth_before_populate(sd);
859 ret = populate_groups(to_config_group(item));
861 configfs_detach_item(item);
862 dentry->d_inode->i_flags |= S_DEAD;
865 configfs_adjust_dir_dirent_depth_after_populate(sd);
866 mutex_unlock(&dentry->d_inode->i_mutex);
874 /* Caller holds the mutex of the group's inode */
875 static void configfs_detach_group(struct config_item *item)
877 detach_groups(to_config_group(item));
878 configfs_detach_item(item);
882 * After the item has been detached from the filesystem view, we are
883 * ready to tear it out of the hierarchy. Notify the client before
884 * we do that so they can perform any cleanup that requires
885 * navigating the hierarchy. A client does not need to provide this
886 * callback. The subsystem semaphore MUST be held by the caller, and
887 * references must be valid for both items. It also assumes the
888 * caller has validated ci_type.
890 static void client_disconnect_notify(struct config_item *parent_item,
891 struct config_item *item)
893 struct config_item_type *type;
895 type = parent_item->ci_type;
898 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
899 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
904 * Drop the initial reference from make_item()/make_group()
905 * This function assumes that reference is held on item
906 * and that item holds a valid reference to the parent. Also, it
907 * assumes the caller has validated ci_type.
909 static void client_drop_item(struct config_item *parent_item,
910 struct config_item *item)
912 struct config_item_type *type;
914 type = parent_item->ci_type;
918 * If ->drop_item() exists, it is responsible for the
921 if (type->ct_group_ops && type->ct_group_ops->drop_item)
922 type->ct_group_ops->drop_item(to_config_group(parent_item),
925 config_item_put(item);
929 static void configfs_dump_one(struct configfs_dirent *sd, int level)
931 printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
933 #define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
934 type_print(CONFIGFS_ROOT);
935 type_print(CONFIGFS_DIR);
936 type_print(CONFIGFS_ITEM_ATTR);
937 type_print(CONFIGFS_ITEM_LINK);
938 type_print(CONFIGFS_USET_DIR);
939 type_print(CONFIGFS_USET_DEFAULT);
940 type_print(CONFIGFS_USET_DROPPING);
944 static int configfs_dump(struct configfs_dirent *sd, int level)
946 struct configfs_dirent *child_sd;
949 configfs_dump_one(sd, level);
951 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
954 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
955 ret = configfs_dump(child_sd, level + 2);
966 * configfs_depend_item() and configfs_undepend_item()
968 * WARNING: Do not call these from a configfs callback!
970 * This describes these functions and their helpers.
972 * Allow another kernel system to depend on a config_item. If this
973 * happens, the item cannot go away until the dependent can live without
974 * it. The idea is to give client modules as simple an interface as
975 * possible. When a system asks them to depend on an item, they just
976 * call configfs_depend_item(). If the item is live and the client
977 * driver is in good shape, we'll happily do the work for them.
979 * Why is the locking complex? Because configfs uses the VFS to handle
980 * all locking, but this function is called outside the normal
981 * VFS->configfs path. So it must take VFS locks to prevent the
982 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
983 * why you can't call these functions underneath configfs callbacks.
985 * Note, btw, that this can be called at *any* time, even when a configfs
986 * subsystem isn't registered, or when configfs is loading or unloading.
987 * Just like configfs_register_subsystem(). So we take the same
988 * precautions. We pin the filesystem. We lock configfs_dirent_lock.
989 * If we can find the target item in the
990 * configfs tree, it must be part of the subsystem tree as well, so we
991 * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
992 * locking out mkdir() and rmdir(), who might be racing us.
996 * configfs_depend_prep()
998 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
999 * attributes. This is similar but not the same to configfs_detach_prep().
1000 * Note that configfs_detach_prep() expects the parent to be locked when it
1001 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1002 * do that so we can unlock it if we find nothing.
1004 * Here we do a depth-first search of the dentry hierarchy looking for
1006 * We deliberately ignore items tagged as dropping since they are virtually
1007 * dead, as well as items in the middle of attachment since they virtually
1008 * do not exist yet. This completes the locking out of racing mkdir() and
1010 * Note: subdirectories in the middle of attachment start with s_type =
1011 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
1012 * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
1013 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1015 * If the target is not found, -ENOENT is bubbled up.
1017 * This adds a requirement that all config_items be unique!
1019 * This is recursive. There isn't
1020 * much on the stack, though, so folks that need this function - be careful
1021 * about your stack! Patches will be accepted to make it iterative.
1023 static int configfs_depend_prep(struct dentry *origin,
1024 struct config_item *target)
1026 struct configfs_dirent *child_sd, *sd;
1029 BUG_ON(!origin || !origin->d_fsdata);
1030 sd = origin->d_fsdata;
1032 if (sd->s_element == target) /* Boo-yah */
1035 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1036 if ((child_sd->s_type & CONFIGFS_DIR) &&
1037 !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1038 !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1039 ret = configfs_depend_prep(child_sd->s_dentry,
1042 goto out; /* Child path boo-yah */
1046 /* We looped all our children and didn't find target */
1053 int configfs_depend_item(struct configfs_subsystem *subsys,
1054 struct config_item *target)
1057 struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
1058 struct config_item *s_item = &subsys->su_group.cg_item;
1059 struct dentry *root;
1062 * Pin the configfs filesystem. This means we can safely access
1063 * the root of the configfs filesystem.
1065 root = configfs_pin_fs();
1067 return PTR_ERR(root);
1070 * Next, lock the root directory. We're going to check that the
1071 * subsystem is really registered, and so we need to lock out
1072 * configfs_[un]register_subsystem().
1074 mutex_lock(&root->d_inode->i_mutex);
1076 root_sd = root->d_fsdata;
1078 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1079 if (p->s_type & CONFIGFS_DIR) {
1080 if (p->s_element == s_item) {
1092 /* Ok, now we can trust subsys/s_item */
1094 spin_lock(&configfs_dirent_lock);
1095 /* Scan the tree, return 0 if found */
1096 ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1098 goto out_unlock_dirent_lock;
1101 * We are sure that the item is not about to be removed by rmdir(), and
1102 * not in the middle of attachment by mkdir().
1104 p = target->ci_dentry->d_fsdata;
1105 p->s_dependent_count += 1;
1107 out_unlock_dirent_lock:
1108 spin_unlock(&configfs_dirent_lock);
1110 mutex_unlock(&root->d_inode->i_mutex);
1113 * If we succeeded, the fs is pinned via other methods. If not,
1114 * we're done with it anyway. So release_fs() is always right.
1116 configfs_release_fs();
1120 EXPORT_SYMBOL(configfs_depend_item);
1123 * Release the dependent linkage. This is much simpler than
1124 * configfs_depend_item() because we know that that the client driver is
1125 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1127 void configfs_undepend_item(struct configfs_subsystem *subsys,
1128 struct config_item *target)
1130 struct configfs_dirent *sd;
1133 * Since we can trust everything is pinned, we just need
1134 * configfs_dirent_lock.
1136 spin_lock(&configfs_dirent_lock);
1138 sd = target->ci_dentry->d_fsdata;
1139 BUG_ON(sd->s_dependent_count < 1);
1141 sd->s_dependent_count -= 1;
1144 * After this unlock, we cannot trust the item to stay alive!
1145 * DO NOT REFERENCE item after this unlock.
1147 spin_unlock(&configfs_dirent_lock);
1149 EXPORT_SYMBOL(configfs_undepend_item);
1151 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1155 struct config_group *group = NULL;
1156 struct config_item *item = NULL;
1157 struct config_item *parent_item;
1158 struct configfs_subsystem *subsys;
1159 struct configfs_dirent *sd;
1160 struct config_item_type *type;
1161 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1164 sd = dentry->d_parent->d_fsdata;
1167 * Fake invisibility if dir belongs to a group/default groups hierarchy
1170 if (!configfs_dirent_is_ready(sd)) {
1175 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1180 /* Get a working ref for the duration of this function */
1181 parent_item = configfs_get_config_item(dentry->d_parent);
1182 type = parent_item->ci_type;
1183 subsys = to_config_group(parent_item)->cg_subsys;
1186 if (!type || !type->ct_group_ops ||
1187 (!type->ct_group_ops->make_group &&
1188 !type->ct_group_ops->make_item)) {
1189 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1194 * The subsystem may belong to a different module than the item
1195 * being created. We don't want to safely pin the new item but
1196 * fail to pin the subsystem it sits under.
1198 if (!subsys->su_group.cg_item.ci_type) {
1202 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1203 if (!try_module_get(subsys_owner)) {
1208 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1211 goto out_subsys_put;
1214 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1216 mutex_lock(&subsys->su_mutex);
1217 if (type->ct_group_ops->make_group) {
1218 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1220 group = ERR_PTR(-ENOMEM);
1221 if (!IS_ERR(group)) {
1222 link_group(to_config_group(parent_item), group);
1223 item = &group->cg_item;
1225 ret = PTR_ERR(group);
1227 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1229 item = ERR_PTR(-ENOMEM);
1231 link_obj(parent_item, item);
1233 ret = PTR_ERR(item);
1235 mutex_unlock(&subsys->su_mutex);
1240 * If ret != 0, then link_obj() was never called.
1241 * There are no extra references to clean up.
1243 goto out_subsys_put;
1247 * link_obj() has been called (via link_group() for groups).
1248 * From here on out, errors must clean that up.
1251 type = item->ci_type;
1257 new_item_owner = type->ct_owner;
1258 if (!try_module_get(new_item_owner)) {
1264 * I hate doing it this way, but if there is
1265 * an error, module_put() probably should
1266 * happen after any cleanup.
1271 * Make racing rmdir() fail if it did not tag parent with
1272 * CONFIGFS_USET_DROPPING
1273 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1274 * fail and let rmdir() terminate correctly
1276 spin_lock(&configfs_dirent_lock);
1277 /* This will make configfs_detach_prep() fail */
1278 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1279 spin_unlock(&configfs_dirent_lock);
1282 ret = configfs_attach_group(parent_item, item, dentry);
1284 ret = configfs_attach_item(parent_item, item, dentry);
1286 spin_lock(&configfs_dirent_lock);
1287 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1289 configfs_dir_set_ready(dentry->d_fsdata);
1290 spin_unlock(&configfs_dirent_lock);
1294 /* Tear down everything we built up */
1295 mutex_lock(&subsys->su_mutex);
1297 client_disconnect_notify(parent_item, item);
1299 unlink_group(group);
1302 client_drop_item(parent_item, item);
1304 mutex_unlock(&subsys->su_mutex);
1307 module_put(new_item_owner);
1312 module_put(subsys_owner);
1316 * link_obj()/link_group() took a reference from child->parent,
1317 * so the parent is safely pinned. We can drop our working
1320 config_item_put(parent_item);
1326 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1328 struct config_item *parent_item;
1329 struct config_item *item;
1330 struct configfs_subsystem *subsys;
1331 struct configfs_dirent *sd;
1332 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1335 sd = dentry->d_fsdata;
1336 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1339 /* Get a working ref until we have the child */
1340 parent_item = configfs_get_config_item(dentry->d_parent);
1341 subsys = to_config_group(parent_item)->cg_subsys;
1344 if (!parent_item->ci_type) {
1345 config_item_put(parent_item);
1349 /* configfs_mkdir() shouldn't have allowed this */
1350 BUG_ON(!subsys->su_group.cg_item.ci_type);
1351 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1354 * Ensure that no racing symlink() will make detach_prep() fail while
1355 * the new link is temporarily attached
1358 struct mutex *wait_mutex;
1360 mutex_lock(&configfs_symlink_mutex);
1361 spin_lock(&configfs_dirent_lock);
1363 * Here's where we check for dependents. We're protected by
1364 * configfs_dirent_lock.
1365 * If no dependent, atomically tag the item as dropping.
1367 ret = sd->s_dependent_count ? -EBUSY : 0;
1369 ret = configfs_detach_prep(dentry, &wait_mutex);
1371 configfs_detach_rollback(dentry);
1373 spin_unlock(&configfs_dirent_lock);
1374 mutex_unlock(&configfs_symlink_mutex);
1377 if (ret != -EAGAIN) {
1378 config_item_put(parent_item);
1382 /* Wait until the racing operation terminates */
1383 mutex_lock(wait_mutex);
1384 mutex_unlock(wait_mutex);
1386 } while (ret == -EAGAIN);
1388 /* Get a working ref for the duration of this function */
1389 item = configfs_get_config_item(dentry);
1391 /* Drop reference from above, item already holds one. */
1392 config_item_put(parent_item);
1395 dead_item_owner = item->ci_type->ct_owner;
1397 if (sd->s_type & CONFIGFS_USET_DIR) {
1398 configfs_detach_group(item);
1400 mutex_lock(&subsys->su_mutex);
1401 client_disconnect_notify(parent_item, item);
1402 unlink_group(to_config_group(item));
1404 configfs_detach_item(item);
1406 mutex_lock(&subsys->su_mutex);
1407 client_disconnect_notify(parent_item, item);
1411 client_drop_item(parent_item, item);
1412 mutex_unlock(&subsys->su_mutex);
1414 /* Drop our reference from above */
1415 config_item_put(item);
1417 module_put(dead_item_owner);
1418 module_put(subsys_owner);
1423 const struct inode_operations configfs_dir_inode_operations = {
1424 .mkdir = configfs_mkdir,
1425 .rmdir = configfs_rmdir,
1426 .symlink = configfs_symlink,
1427 .unlink = configfs_unlink,
1428 .lookup = configfs_lookup,
1429 .setattr = configfs_setattr,
1432 const struct inode_operations configfs_root_inode_operations = {
1433 .lookup = configfs_lookup,
1434 .setattr = configfs_setattr,
1438 int configfs_rename_dir(struct config_item * item, const char *new_name)
1441 struct dentry * new_dentry, * parent;
1443 if (!strcmp(config_item_name(item), new_name))
1449 down_write(&configfs_rename_sem);
1450 parent = item->parent->dentry;
1452 mutex_lock(&parent->d_inode->i_mutex);
1454 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1455 if (!IS_ERR(new_dentry)) {
1456 if (!new_dentry->d_inode) {
1457 error = config_item_set_name(item, "%s", new_name);
1459 d_add(new_dentry, NULL);
1460 d_move(item->dentry, new_dentry);
1463 d_delete(new_dentry);
1468 mutex_unlock(&parent->d_inode->i_mutex);
1469 up_write(&configfs_rename_sem);
1475 static int configfs_dir_open(struct inode *inode, struct file *file)
1477 struct dentry * dentry = file->f_path.dentry;
1478 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1481 mutex_lock(&dentry->d_inode->i_mutex);
1483 * Fake invisibility if dir belongs to a group/default groups hierarchy
1487 if (configfs_dirent_is_ready(parent_sd)) {
1488 file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
1489 if (IS_ERR(file->private_data))
1490 err = PTR_ERR(file->private_data);
1494 mutex_unlock(&dentry->d_inode->i_mutex);
1499 static int configfs_dir_close(struct inode *inode, struct file *file)
1501 struct dentry * dentry = file->f_path.dentry;
1502 struct configfs_dirent * cursor = file->private_data;
1504 mutex_lock(&dentry->d_inode->i_mutex);
1505 spin_lock(&configfs_dirent_lock);
1506 list_del_init(&cursor->s_sibling);
1507 spin_unlock(&configfs_dirent_lock);
1508 mutex_unlock(&dentry->d_inode->i_mutex);
1510 release_configfs_dirent(cursor);
1515 /* Relationship between s_mode and the DT_xxx types */
1516 static inline unsigned char dt_type(struct configfs_dirent *sd)
1518 return (sd->s_mode >> 12) & 15;
1521 static int configfs_readdir(struct file *file, struct dir_context *ctx)
1523 struct dentry *dentry = file->f_path.dentry;
1524 struct super_block *sb = dentry->d_sb;
1525 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1526 struct configfs_dirent *cursor = file->private_data;
1527 struct list_head *p, *q = &cursor->s_sibling;
1530 if (!dir_emit_dots(file, ctx))
1532 if (ctx->pos == 2) {
1533 spin_lock(&configfs_dirent_lock);
1534 list_move(q, &parent_sd->s_children);
1535 spin_unlock(&configfs_dirent_lock);
1537 for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1538 struct configfs_dirent *next;
1541 struct inode *inode = NULL;
1543 next = list_entry(p, struct configfs_dirent, s_sibling);
1544 if (!next->s_element)
1547 name = configfs_get_name(next);
1551 * We'll have a dentry and an inode for
1552 * PINNED items and for open attribute
1553 * files. We lock here to prevent a race
1554 * with configfs_d_iput() clearing
1555 * s_dentry before calling iput().
1557 * Why do we go to the trouble? If
1558 * someone has an attribute file open,
1559 * the inode number should match until
1560 * they close it. Beyond that, we don't
1563 spin_lock(&configfs_dirent_lock);
1564 dentry = next->s_dentry;
1566 inode = dentry->d_inode;
1569 spin_unlock(&configfs_dirent_lock);
1571 ino = iunique(sb, 2);
1573 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1576 spin_lock(&configfs_dirent_lock);
1578 spin_unlock(&configfs_dirent_lock);
1585 static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1587 struct dentry * dentry = file->f_path.dentry;
1589 mutex_lock(&dentry->d_inode->i_mutex);
1592 offset += file->f_pos;
1597 mutex_unlock(&file_inode(file)->i_mutex);
1600 if (offset != file->f_pos) {
1601 file->f_pos = offset;
1602 if (file->f_pos >= 2) {
1603 struct configfs_dirent *sd = dentry->d_fsdata;
1604 struct configfs_dirent *cursor = file->private_data;
1605 struct list_head *p;
1606 loff_t n = file->f_pos - 2;
1608 spin_lock(&configfs_dirent_lock);
1609 list_del(&cursor->s_sibling);
1610 p = sd->s_children.next;
1611 while (n && p != &sd->s_children) {
1612 struct configfs_dirent *next;
1613 next = list_entry(p, struct configfs_dirent,
1615 if (next->s_element)
1619 list_add_tail(&cursor->s_sibling, p);
1620 spin_unlock(&configfs_dirent_lock);
1623 mutex_unlock(&dentry->d_inode->i_mutex);
1627 const struct file_operations configfs_dir_operations = {
1628 .open = configfs_dir_open,
1629 .release = configfs_dir_close,
1630 .llseek = configfs_dir_lseek,
1631 .read = generic_read_dir,
1632 .iterate = configfs_readdir,
1635 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1638 struct config_group *group = &subsys->su_group;
1639 struct dentry *dentry;
1640 struct dentry *root;
1641 struct configfs_dirent *sd;
1643 root = configfs_pin_fs();
1645 return PTR_ERR(root);
1647 if (!group->cg_item.ci_name)
1648 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1650 sd = root->d_fsdata;
1651 link_group(to_config_group(sd->s_element), group);
1653 mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_PARENT);
1656 dentry = d_alloc_name(root, group->cg_item.ci_name);
1658 d_add(dentry, NULL);
1660 err = configfs_attach_group(sd->s_element, &group->cg_item,
1663 BUG_ON(dentry->d_inode);
1667 spin_lock(&configfs_dirent_lock);
1668 configfs_dir_set_ready(dentry->d_fsdata);
1669 spin_unlock(&configfs_dirent_lock);
1673 mutex_unlock(&root->d_inode->i_mutex);
1676 unlink_group(group);
1677 configfs_release_fs();
1683 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1685 struct config_group *group = &subsys->su_group;
1686 struct dentry *dentry = group->cg_item.ci_dentry;
1687 struct dentry *root = dentry->d_sb->s_root;
1689 if (dentry->d_parent != root) {
1690 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1694 mutex_lock_nested(&root->d_inode->i_mutex,
1696 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
1697 mutex_lock(&configfs_symlink_mutex);
1698 spin_lock(&configfs_dirent_lock);
1699 if (configfs_detach_prep(dentry, NULL)) {
1700 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1702 spin_unlock(&configfs_dirent_lock);
1703 mutex_unlock(&configfs_symlink_mutex);
1704 configfs_detach_group(&group->cg_item);
1705 dentry->d_inode->i_flags |= S_DEAD;
1707 mutex_unlock(&dentry->d_inode->i_mutex);
1711 mutex_unlock(&root->d_inode->i_mutex);
1715 unlink_group(group);
1716 configfs_release_fs();
1719 EXPORT_SYMBOL(configfs_register_subsystem);
1720 EXPORT_SYMBOL(configfs_unregister_subsystem);