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,
84 * Helpers to make lockdep happy with our recursive locking of default groups'
85 * inodes (see configfs_attach_group() and configfs_detach_group()).
86 * We put default groups i_mutexes in separate classes according to their depth
87 * from the youngest non-default group ancestor.
89 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
90 * groups A/B and A/C will have their inode's mutex in class
91 * default_group_class[0], and default group A/C/D will be in
92 * default_group_class[1].
94 * The lock classes are declared and assigned in inode.c, according to the
96 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
97 * default groups, and reset to -1 when all default groups are attached. During
98 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
99 * inode's mutex is set to default_group_class[s_depth - 1].
102 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
107 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
108 struct configfs_dirent *sd)
110 int parent_depth = parent_sd->s_depth;
112 if (parent_depth >= 0)
113 sd->s_depth = parent_depth + 1;
117 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
120 * item's i_mutex class is already setup, so s_depth is now only
121 * used to set new sub-directories s_depth, which is always done
122 * with item's i_mutex locked.
125 * sd->s_depth == -1 iff we are a non default group.
126 * else (we are a default group) sd->s_depth > 0 (see
129 if (sd->s_depth == -1)
131 * We are a non default group and we are going to create
138 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
140 /* We will not create default groups anymore. */
144 #else /* CONFIG_LOCKDEP */
146 static void configfs_init_dirent_depth(struct configfs_dirent *sd)
150 static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
151 struct configfs_dirent *sd)
156 configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
161 configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
165 #endif /* CONFIG_LOCKDEP */
168 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
170 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * parent_sd,
173 struct configfs_dirent * sd;
175 sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
177 return ERR_PTR(-ENOMEM);
179 atomic_set(&sd->s_count, 1);
180 INIT_LIST_HEAD(&sd->s_links);
181 INIT_LIST_HEAD(&sd->s_children);
182 sd->s_element = element;
183 configfs_init_dirent_depth(sd);
184 spin_lock(&configfs_dirent_lock);
185 if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
186 spin_unlock(&configfs_dirent_lock);
187 kmem_cache_free(configfs_dir_cachep, sd);
188 return ERR_PTR(-ENOENT);
190 list_add(&sd->s_sibling, &parent_sd->s_children);
191 spin_unlock(&configfs_dirent_lock);
198 * Return -EEXIST if there is already a configfs element with the same
199 * name for the same parent.
201 * called with parent inode's i_mutex held
203 static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
204 const unsigned char *new)
206 struct configfs_dirent * sd;
208 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
210 const unsigned char *existing = configfs_get_name(sd);
211 if (strcmp(existing, new))
222 int configfs_make_dirent(struct configfs_dirent * parent_sd,
223 struct dentry * dentry, void * element,
224 umode_t mode, int type)
226 struct configfs_dirent * sd;
228 sd = configfs_new_dirent(parent_sd, element);
234 sd->s_dentry = dentry;
236 dentry->d_fsdata = configfs_get(sd);
237 dentry->d_op = &configfs_dentry_ops;
243 static int init_dir(struct inode * inode)
245 inode->i_op = &configfs_dir_inode_operations;
246 inode->i_fop = &configfs_dir_operations;
248 /* directory inodes start off with i_nlink == 2 (for "." entry) */
253 static int configfs_init_file(struct inode * inode)
255 inode->i_size = PAGE_SIZE;
256 inode->i_fop = &configfs_file_operations;
260 static int init_symlink(struct inode * inode)
262 inode->i_op = &configfs_symlink_inode_operations;
266 static int create_dir(struct config_item * k, struct dentry * p,
270 umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
272 error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
274 error = configfs_make_dirent(p->d_fsdata, d, k, mode,
275 CONFIGFS_DIR | CONFIGFS_USET_CREATING);
277 configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
278 error = configfs_create(d, mode, init_dir);
280 inc_nlink(p->d_inode);
281 (d)->d_op = &configfs_dentry_ops;
283 struct configfs_dirent *sd = d->d_fsdata;
285 spin_lock(&configfs_dirent_lock);
286 list_del_init(&sd->s_sibling);
287 spin_unlock(&configfs_dirent_lock);
297 * configfs_create_dir - create a directory for an config_item.
298 * @item: config_itemwe're creating directory for.
299 * @dentry: config_item's dentry.
301 * Note: user-created entries won't be allowed under this new directory
302 * until it is validated by configfs_dir_set_ready()
305 static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
307 struct dentry * parent;
313 parent = item->ci_parent->ci_dentry;
314 else if (configfs_mount && configfs_mount->mnt_sb)
315 parent = configfs_mount->mnt_sb->s_root;
319 error = create_dir(item,parent,dentry);
321 item->ci_dentry = dentry;
326 * Allow userspace to create new entries under a new directory created with
327 * configfs_create_dir(), and under all of its chidlren directories recursively.
328 * @sd configfs_dirent of the new directory to validate
330 * Caller must hold configfs_dirent_lock.
332 static void configfs_dir_set_ready(struct configfs_dirent *sd)
334 struct configfs_dirent *child_sd;
336 sd->s_type &= ~CONFIGFS_USET_CREATING;
337 list_for_each_entry(child_sd, &sd->s_children, s_sibling)
338 if (child_sd->s_type & CONFIGFS_USET_CREATING)
339 configfs_dir_set_ready(child_sd);
343 * Check that a directory does not belong to a directory hierarchy being
344 * attached and not validated yet.
345 * @sd configfs_dirent of the directory to check
347 * @return non-zero iff the directory was validated
349 * Note: takes configfs_dirent_lock, so the result may change from false to true
350 * in two consecutive calls, but never from true to false.
352 int configfs_dirent_is_ready(struct configfs_dirent *sd)
356 spin_lock(&configfs_dirent_lock);
357 ret = !(sd->s_type & CONFIGFS_USET_CREATING);
358 spin_unlock(&configfs_dirent_lock);
363 int configfs_create_link(struct configfs_symlink *sl,
364 struct dentry *parent,
365 struct dentry *dentry)
368 umode_t mode = S_IFLNK | S_IRWXUGO;
370 err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
373 err = configfs_create(dentry, mode, init_symlink);
375 dentry->d_op = &configfs_dentry_ops;
377 struct configfs_dirent *sd = dentry->d_fsdata;
379 spin_lock(&configfs_dirent_lock);
380 list_del_init(&sd->s_sibling);
381 spin_unlock(&configfs_dirent_lock);
389 static void remove_dir(struct dentry * d)
391 struct dentry * parent = dget(d->d_parent);
392 struct configfs_dirent * sd;
395 spin_lock(&configfs_dirent_lock);
396 list_del_init(&sd->s_sibling);
397 spin_unlock(&configfs_dirent_lock);
400 simple_rmdir(parent->d_inode,d);
402 pr_debug(" o %s removing done (%d)\n",d->d_name.name,
403 atomic_read(&d->d_count));
409 * configfs_remove_dir - remove an config_item's directory.
410 * @item: config_item we're removing.
412 * The only thing special about this is that we remove any files in
413 * the directory before we remove the directory, and we've inlined
414 * what used to be configfs_rmdir() below, instead of calling separately.
416 * Caller holds the mutex of the item's inode
419 static void configfs_remove_dir(struct config_item * item)
421 struct dentry * dentry = dget(item->ci_dentry);
428 * Drop reference from dget() on entrance.
434 /* attaches attribute's configfs_dirent to the dentry corresponding to the
437 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
439 struct configfs_attribute * attr = sd->s_element;
442 dentry->d_fsdata = configfs_get(sd);
443 sd->s_dentry = dentry;
444 error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
451 dentry->d_op = &configfs_dentry_ops;
457 static struct dentry * configfs_lookup(struct inode *dir,
458 struct dentry *dentry,
459 struct nameidata *nd)
461 struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
462 struct configfs_dirent * sd;
467 * Fake invisibility if dir belongs to a group/default groups hierarchy
470 * This forbids userspace to read/write attributes of items which may
471 * not complete their initialization, since the dentries of the
472 * attributes won't be instantiated.
475 if (!configfs_dirent_is_ready(parent_sd))
478 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
479 if (sd->s_type & CONFIGFS_NOT_PINNED) {
480 const unsigned char * name = configfs_get_name(sd);
482 if (strcmp(name, dentry->d_name.name))
486 err = configfs_attach_attr(sd, dentry);
493 * If it doesn't exist and it isn't a NOT_PINNED item,
494 * it must be negative.
496 return simple_lookup(dir, dentry, nd);
504 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
505 * attributes and are removed by rmdir(). We recurse, setting
506 * CONFIGFS_USET_DROPPING on all children that are candidates for
508 * If there is an error, the caller will reset the flags via
509 * configfs_detach_rollback().
511 static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
513 struct configfs_dirent *parent_sd = dentry->d_fsdata;
514 struct configfs_dirent *sd;
517 /* Mark that we're trying to drop the group */
518 parent_sd->s_type |= CONFIGFS_USET_DROPPING;
521 if (!list_empty(&parent_sd->s_links))
525 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
526 if (!sd->s_element ||
527 (sd->s_type & CONFIGFS_NOT_PINNED))
529 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
530 /* Abort if racing with mkdir() */
531 if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
533 *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
538 * Yup, recursive. If there's a problem, blame
539 * deep nesting of default_groups
541 ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
555 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
558 static void configfs_detach_rollback(struct dentry *dentry)
560 struct configfs_dirent *parent_sd = dentry->d_fsdata;
561 struct configfs_dirent *sd;
563 parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
565 list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
566 if (sd->s_type & CONFIGFS_USET_DEFAULT)
567 configfs_detach_rollback(sd->s_dentry);
570 static void detach_attrs(struct config_item * item)
572 struct dentry * dentry = dget(item->ci_dentry);
573 struct configfs_dirent * parent_sd;
574 struct configfs_dirent * sd, * tmp;
579 pr_debug("configfs %s: dropping attrs for dir\n",
580 dentry->d_name.name);
582 parent_sd = dentry->d_fsdata;
583 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
584 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
586 spin_lock(&configfs_dirent_lock);
587 list_del_init(&sd->s_sibling);
588 spin_unlock(&configfs_dirent_lock);
589 configfs_drop_dentry(sd, dentry);
594 * Drop reference from dget() on entrance.
599 static int populate_attrs(struct config_item *item)
601 struct config_item_type *t = item->ci_type;
602 struct configfs_attribute *attr;
609 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
610 if ((error = configfs_create_file(item, attr)))
621 static int configfs_attach_group(struct config_item *parent_item,
622 struct config_item *item,
623 struct dentry *dentry);
624 static void configfs_detach_group(struct config_item *item);
626 static void detach_groups(struct config_group *group)
628 struct dentry * dentry = dget(group->cg_item.ci_dentry);
629 struct dentry *child;
630 struct configfs_dirent *parent_sd;
631 struct configfs_dirent *sd, *tmp;
636 parent_sd = dentry->d_fsdata;
637 list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
638 if (!sd->s_element ||
639 !(sd->s_type & CONFIGFS_USET_DEFAULT))
642 child = sd->s_dentry;
644 mutex_lock(&child->d_inode->i_mutex);
646 configfs_detach_group(sd->s_element);
647 child->d_inode->i_flags |= S_DEAD;
649 mutex_unlock(&child->d_inode->i_mutex);
656 * Drop reference from dget() on entrance.
662 * This fakes mkdir(2) on a default_groups[] entry. It
663 * creates a dentry, attachs it, and then does fixup
666 * We could, perhaps, tweak our parent's ->mkdir for a minute and
667 * try using vfs_mkdir. Just a thought.
669 static int create_default_group(struct config_group *parent_group,
670 struct config_group *group)
674 struct configfs_dirent *sd;
675 /* We trust the caller holds a reference to parent */
676 struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
678 if (!group->cg_item.ci_name)
679 group->cg_item.ci_name = group->cg_item.ci_namebuf;
680 name.name = group->cg_item.ci_name;
681 name.len = strlen(name.name);
682 name.hash = full_name_hash(name.name, name.len);
685 child = d_alloc(parent, &name);
689 ret = configfs_attach_group(&parent_group->cg_item,
690 &group->cg_item, child);
692 sd = child->d_fsdata;
693 sd->s_type |= CONFIGFS_USET_DEFAULT;
703 static int populate_groups(struct config_group *group)
705 struct config_group *new_group;
709 if (group->default_groups) {
710 for (i = 0; group->default_groups[i]; i++) {
711 new_group = group->default_groups[i];
713 ret = create_default_group(group, new_group);
715 detach_groups(group);
725 * All of link_obj/unlink_obj/link_group/unlink_group require that
726 * subsys->su_mutex is held.
729 static void unlink_obj(struct config_item *item)
731 struct config_group *group;
733 group = item->ci_group;
735 list_del_init(&item->ci_entry);
737 item->ci_group = NULL;
738 item->ci_parent = NULL;
740 /* Drop the reference for ci_entry */
741 config_item_put(item);
743 /* Drop the reference for ci_parent */
744 config_group_put(group);
748 static void link_obj(struct config_item *parent_item, struct config_item *item)
751 * Parent seems redundant with group, but it makes certain
752 * traversals much nicer.
754 item->ci_parent = parent_item;
757 * We hold a reference on the parent for the child's ci_parent
760 item->ci_group = config_group_get(to_config_group(parent_item));
761 list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
764 * We hold a reference on the child for ci_entry on the parent's
767 config_item_get(item);
770 static void unlink_group(struct config_group *group)
773 struct config_group *new_group;
775 if (group->default_groups) {
776 for (i = 0; group->default_groups[i]; i++) {
777 new_group = group->default_groups[i];
778 unlink_group(new_group);
782 group->cg_subsys = NULL;
783 unlink_obj(&group->cg_item);
786 static void link_group(struct config_group *parent_group, struct config_group *group)
789 struct config_group *new_group;
790 struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
792 link_obj(&parent_group->cg_item, &group->cg_item);
794 if (parent_group->cg_subsys)
795 subsys = parent_group->cg_subsys;
796 else if (configfs_is_root(&parent_group->cg_item))
797 subsys = to_configfs_subsystem(group);
800 group->cg_subsys = subsys;
802 if (group->default_groups) {
803 for (i = 0; group->default_groups[i]; i++) {
804 new_group = group->default_groups[i];
805 link_group(group, new_group);
811 * The goal is that configfs_attach_item() (and
812 * configfs_attach_group()) can be called from either the VFS or this
813 * module. That is, they assume that the items have been created,
814 * the dentry allocated, and the dcache is all ready to go.
816 * If they fail, they must clean up after themselves as if they
817 * had never been called. The caller (VFS or local function) will
818 * handle cleaning up the dcache bits.
820 * configfs_detach_group() and configfs_detach_item() behave similarly on
821 * the way out. They assume that the proper semaphores are held, they
822 * clean up the configfs items, and they expect their callers will
823 * handle the dcache bits.
825 static int configfs_attach_item(struct config_item *parent_item,
826 struct config_item *item,
827 struct dentry *dentry)
831 ret = configfs_create_dir(item, dentry);
833 ret = populate_attrs(item);
836 * We are going to remove an inode and its dentry but
837 * the VFS may already have hit and used them. Thus,
838 * we must lock them as rmdir() would.
840 mutex_lock(&dentry->d_inode->i_mutex);
841 configfs_remove_dir(item);
842 dentry->d_inode->i_flags |= S_DEAD;
843 mutex_unlock(&dentry->d_inode->i_mutex);
851 /* Caller holds the mutex of the item's inode */
852 static void configfs_detach_item(struct config_item *item)
855 configfs_remove_dir(item);
858 static int configfs_attach_group(struct config_item *parent_item,
859 struct config_item *item,
860 struct dentry *dentry)
863 struct configfs_dirent *sd;
865 ret = configfs_attach_item(parent_item, item, dentry);
867 sd = dentry->d_fsdata;
868 sd->s_type |= CONFIGFS_USET_DIR;
871 * FYI, we're faking mkdir in populate_groups()
872 * We must lock the group's inode to avoid races with the VFS
873 * which can already hit the inode and try to add/remove entries
876 * We must also lock the inode to remove it safely in case of
877 * error, as rmdir() would.
879 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
880 configfs_adjust_dir_dirent_depth_before_populate(sd);
881 ret = populate_groups(to_config_group(item));
883 configfs_detach_item(item);
884 dentry->d_inode->i_flags |= S_DEAD;
886 configfs_adjust_dir_dirent_depth_after_populate(sd);
887 mutex_unlock(&dentry->d_inode->i_mutex);
895 /* Caller holds the mutex of the group's inode */
896 static void configfs_detach_group(struct config_item *item)
898 detach_groups(to_config_group(item));
899 configfs_detach_item(item);
903 * After the item has been detached from the filesystem view, we are
904 * ready to tear it out of the hierarchy. Notify the client before
905 * we do that so they can perform any cleanup that requires
906 * navigating the hierarchy. A client does not need to provide this
907 * callback. The subsystem semaphore MUST be held by the caller, and
908 * references must be valid for both items. It also assumes the
909 * caller has validated ci_type.
911 static void client_disconnect_notify(struct config_item *parent_item,
912 struct config_item *item)
914 struct config_item_type *type;
916 type = parent_item->ci_type;
919 if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
920 type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
925 * Drop the initial reference from make_item()/make_group()
926 * This function assumes that reference is held on item
927 * and that item holds a valid reference to the parent. Also, it
928 * assumes the caller has validated ci_type.
930 static void client_drop_item(struct config_item *parent_item,
931 struct config_item *item)
933 struct config_item_type *type;
935 type = parent_item->ci_type;
939 * If ->drop_item() exists, it is responsible for the
942 if (type->ct_group_ops && type->ct_group_ops->drop_item)
943 type->ct_group_ops->drop_item(to_config_group(parent_item),
946 config_item_put(item);
950 static void configfs_dump_one(struct configfs_dirent *sd, int level)
952 printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
954 #define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
955 type_print(CONFIGFS_ROOT);
956 type_print(CONFIGFS_DIR);
957 type_print(CONFIGFS_ITEM_ATTR);
958 type_print(CONFIGFS_ITEM_LINK);
959 type_print(CONFIGFS_USET_DIR);
960 type_print(CONFIGFS_USET_DEFAULT);
961 type_print(CONFIGFS_USET_DROPPING);
965 static int configfs_dump(struct configfs_dirent *sd, int level)
967 struct configfs_dirent *child_sd;
970 configfs_dump_one(sd, level);
972 if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
975 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
976 ret = configfs_dump(child_sd, level + 2);
987 * configfs_depend_item() and configfs_undepend_item()
989 * WARNING: Do not call these from a configfs callback!
991 * This describes these functions and their helpers.
993 * Allow another kernel system to depend on a config_item. If this
994 * happens, the item cannot go away until the dependant can live without
995 * it. The idea is to give client modules as simple an interface as
996 * possible. When a system asks them to depend on an item, they just
997 * call configfs_depend_item(). If the item is live and the client
998 * driver is in good shape, we'll happily do the work for them.
1000 * Why is the locking complex? Because configfs uses the VFS to handle
1001 * all locking, but this function is called outside the normal
1002 * VFS->configfs path. So it must take VFS locks to prevent the
1003 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
1004 * why you can't call these functions underneath configfs callbacks.
1006 * Note, btw, that this can be called at *any* time, even when a configfs
1007 * subsystem isn't registered, or when configfs is loading or unloading.
1008 * Just like configfs_register_subsystem(). So we take the same
1009 * precautions. We pin the filesystem. We lock each i_mutex _in_order_
1010 * on our way down the tree. If we can find the target item in the
1011 * configfs tree, it must be part of the subsystem tree as well, so we
1012 * do not need the subsystem semaphore. Holding the i_mutex chain locks
1013 * out mkdir() and rmdir(), who might be racing us.
1017 * configfs_depend_prep()
1019 * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
1020 * attributes. This is similar but not the same to configfs_detach_prep().
1021 * Note that configfs_detach_prep() expects the parent to be locked when it
1022 * is called, but we lock the parent *inside* configfs_depend_prep(). We
1023 * do that so we can unlock it if we find nothing.
1025 * Here we do a depth-first search of the dentry hierarchy looking for
1026 * our object. We take i_mutex on each step of the way down. IT IS
1027 * ESSENTIAL THAT i_mutex LOCKING IS ORDERED. If we come back up a branch,
1028 * we'll drop the i_mutex.
1030 * If the target is not found, -ENOENT is bubbled up and we have released
1031 * all locks. If the target was found, the locks will be cleared by
1032 * configfs_depend_rollback().
1034 * This adds a requirement that all config_items be unique!
1036 * This is recursive because the locking traversal is tricky. There isn't
1037 * much on the stack, though, so folks that need this function - be careful
1038 * about your stack! Patches will be accepted to make it iterative.
1040 static int configfs_depend_prep(struct dentry *origin,
1041 struct config_item *target)
1043 struct configfs_dirent *child_sd, *sd = origin->d_fsdata;
1046 BUG_ON(!origin || !sd);
1048 /* Lock this guy on the way down */
1049 mutex_lock(&sd->s_dentry->d_inode->i_mutex);
1050 if (sd->s_element == target) /* Boo-yah */
1053 list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1054 if (child_sd->s_type & CONFIGFS_DIR) {
1055 ret = configfs_depend_prep(child_sd->s_dentry,
1058 goto out; /* Child path boo-yah */
1062 /* We looped all our children and didn't find target */
1063 mutex_unlock(&sd->s_dentry->d_inode->i_mutex);
1071 * This is ONLY called if configfs_depend_prep() did its job. So we can
1072 * trust the entire path from item back up to origin.
1074 * We walk backwards from item, unlocking each i_mutex. We finish by
1077 static void configfs_depend_rollback(struct dentry *origin,
1078 struct config_item *item)
1080 struct dentry *dentry = item->ci_dentry;
1082 while (dentry != origin) {
1083 mutex_unlock(&dentry->d_inode->i_mutex);
1084 dentry = dentry->d_parent;
1087 mutex_unlock(&origin->d_inode->i_mutex);
1090 int configfs_depend_item(struct configfs_subsystem *subsys,
1091 struct config_item *target)
1094 struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
1095 struct config_item *s_item = &subsys->su_group.cg_item;
1098 * Pin the configfs filesystem. This means we can safely access
1099 * the root of the configfs filesystem.
1101 ret = configfs_pin_fs();
1106 * Next, lock the root directory. We're going to check that the
1107 * subsystem is really registered, and so we need to lock out
1108 * configfs_[un]register_subsystem().
1110 mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1112 root_sd = configfs_sb->s_root->d_fsdata;
1114 list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1115 if (p->s_type & CONFIGFS_DIR) {
1116 if (p->s_element == s_item) {
1128 /* Ok, now we can trust subsys/s_item */
1130 /* Scan the tree, locking i_mutex recursively, return 0 if found */
1131 ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1135 /* We hold all i_mutexes from the subsystem down to the target */
1136 p = target->ci_dentry->d_fsdata;
1137 p->s_dependent_count += 1;
1139 configfs_depend_rollback(subsys_sd->s_dentry, target);
1142 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1145 * If we succeeded, the fs is pinned via other methods. If not,
1146 * we're done with it anyway. So release_fs() is always right.
1148 configfs_release_fs();
1152 EXPORT_SYMBOL(configfs_depend_item);
1155 * Release the dependent linkage. This is much simpler than
1156 * configfs_depend_item() because we know that that the client driver is
1157 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1159 void configfs_undepend_item(struct configfs_subsystem *subsys,
1160 struct config_item *target)
1162 struct configfs_dirent *sd;
1165 * Since we can trust everything is pinned, we just need i_mutex
1168 mutex_lock(&target->ci_dentry->d_inode->i_mutex);
1170 sd = target->ci_dentry->d_fsdata;
1171 BUG_ON(sd->s_dependent_count < 1);
1173 sd->s_dependent_count -= 1;
1176 * After this unlock, we cannot trust the item to stay alive!
1177 * DO NOT REFERENCE item after this unlock.
1179 mutex_unlock(&target->ci_dentry->d_inode->i_mutex);
1181 EXPORT_SYMBOL(configfs_undepend_item);
1183 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1187 struct config_group *group = NULL;
1188 struct config_item *item = NULL;
1189 struct config_item *parent_item;
1190 struct configfs_subsystem *subsys;
1191 struct configfs_dirent *sd;
1192 struct config_item_type *type;
1193 struct module *subsys_owner = NULL, *new_item_owner = NULL;
1196 if (dentry->d_parent == configfs_sb->s_root) {
1201 sd = dentry->d_parent->d_fsdata;
1204 * Fake invisibility if dir belongs to a group/default groups hierarchy
1207 if (!configfs_dirent_is_ready(sd)) {
1212 if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1217 /* Get a working ref for the duration of this function */
1218 parent_item = configfs_get_config_item(dentry->d_parent);
1219 type = parent_item->ci_type;
1220 subsys = to_config_group(parent_item)->cg_subsys;
1223 if (!type || !type->ct_group_ops ||
1224 (!type->ct_group_ops->make_group &&
1225 !type->ct_group_ops->make_item)) {
1226 ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
1231 * The subsystem may belong to a different module than the item
1232 * being created. We don't want to safely pin the new item but
1233 * fail to pin the subsystem it sits under.
1235 if (!subsys->su_group.cg_item.ci_type) {
1239 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1240 if (!try_module_get(subsys_owner)) {
1245 name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1248 goto out_subsys_put;
1251 snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1253 mutex_lock(&subsys->su_mutex);
1254 if (type->ct_group_ops->make_group) {
1255 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1257 group = ERR_PTR(-ENOMEM);
1258 if (!IS_ERR(group)) {
1259 link_group(to_config_group(parent_item), group);
1260 item = &group->cg_item;
1262 ret = PTR_ERR(group);
1264 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1266 item = ERR_PTR(-ENOMEM);
1268 link_obj(parent_item, item);
1270 ret = PTR_ERR(item);
1272 mutex_unlock(&subsys->su_mutex);
1277 * If ret != 0, then link_obj() was never called.
1278 * There are no extra references to clean up.
1280 goto out_subsys_put;
1284 * link_obj() has been called (via link_group() for groups).
1285 * From here on out, errors must clean that up.
1288 type = item->ci_type;
1294 new_item_owner = type->ct_owner;
1295 if (!try_module_get(new_item_owner)) {
1301 * I hate doing it this way, but if there is
1302 * an error, module_put() probably should
1303 * happen after any cleanup.
1308 * Make racing rmdir() fail if it did not tag parent with
1309 * CONFIGFS_USET_DROPPING
1310 * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1311 * fail and let rmdir() terminate correctly
1313 spin_lock(&configfs_dirent_lock);
1314 /* This will make configfs_detach_prep() fail */
1315 sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1316 spin_unlock(&configfs_dirent_lock);
1319 ret = configfs_attach_group(parent_item, item, dentry);
1321 ret = configfs_attach_item(parent_item, item, dentry);
1323 spin_lock(&configfs_dirent_lock);
1324 sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1326 configfs_dir_set_ready(dentry->d_fsdata);
1327 spin_unlock(&configfs_dirent_lock);
1331 /* Tear down everything we built up */
1332 mutex_lock(&subsys->su_mutex);
1334 client_disconnect_notify(parent_item, item);
1336 unlink_group(group);
1339 client_drop_item(parent_item, item);
1341 mutex_unlock(&subsys->su_mutex);
1344 module_put(new_item_owner);
1349 module_put(subsys_owner);
1353 * link_obj()/link_group() took a reference from child->parent,
1354 * so the parent is safely pinned. We can drop our working
1357 config_item_put(parent_item);
1363 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1365 struct config_item *parent_item;
1366 struct config_item *item;
1367 struct configfs_subsystem *subsys;
1368 struct configfs_dirent *sd;
1369 struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1372 if (dentry->d_parent == configfs_sb->s_root)
1375 sd = dentry->d_fsdata;
1376 if (sd->s_type & CONFIGFS_USET_DEFAULT)
1380 * Here's where we check for dependents. We're protected by
1383 if (sd->s_dependent_count)
1386 /* Get a working ref until we have the child */
1387 parent_item = configfs_get_config_item(dentry->d_parent);
1388 subsys = to_config_group(parent_item)->cg_subsys;
1391 if (!parent_item->ci_type) {
1392 config_item_put(parent_item);
1396 /* configfs_mkdir() shouldn't have allowed this */
1397 BUG_ON(!subsys->su_group.cg_item.ci_type);
1398 subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1401 * Ensure that no racing symlink() will make detach_prep() fail while
1402 * the new link is temporarily attached
1405 struct mutex *wait_mutex;
1407 mutex_lock(&configfs_symlink_mutex);
1408 spin_lock(&configfs_dirent_lock);
1409 ret = configfs_detach_prep(dentry, &wait_mutex);
1411 configfs_detach_rollback(dentry);
1412 spin_unlock(&configfs_dirent_lock);
1413 mutex_unlock(&configfs_symlink_mutex);
1416 if (ret != -EAGAIN) {
1417 config_item_put(parent_item);
1421 /* Wait until the racing operation terminates */
1422 mutex_lock(wait_mutex);
1423 mutex_unlock(wait_mutex);
1425 } while (ret == -EAGAIN);
1427 /* Get a working ref for the duration of this function */
1428 item = configfs_get_config_item(dentry);
1430 /* Drop reference from above, item already holds one. */
1431 config_item_put(parent_item);
1434 dead_item_owner = item->ci_type->ct_owner;
1436 if (sd->s_type & CONFIGFS_USET_DIR) {
1437 configfs_detach_group(item);
1439 mutex_lock(&subsys->su_mutex);
1440 client_disconnect_notify(parent_item, item);
1441 unlink_group(to_config_group(item));
1443 configfs_detach_item(item);
1445 mutex_lock(&subsys->su_mutex);
1446 client_disconnect_notify(parent_item, item);
1450 client_drop_item(parent_item, item);
1451 mutex_unlock(&subsys->su_mutex);
1453 /* Drop our reference from above */
1454 config_item_put(item);
1456 module_put(dead_item_owner);
1457 module_put(subsys_owner);
1462 const struct inode_operations configfs_dir_inode_operations = {
1463 .mkdir = configfs_mkdir,
1464 .rmdir = configfs_rmdir,
1465 .symlink = configfs_symlink,
1466 .unlink = configfs_unlink,
1467 .lookup = configfs_lookup,
1468 .setattr = configfs_setattr,
1472 int configfs_rename_dir(struct config_item * item, const char *new_name)
1475 struct dentry * new_dentry, * parent;
1477 if (!strcmp(config_item_name(item), new_name))
1483 down_write(&configfs_rename_sem);
1484 parent = item->parent->dentry;
1486 mutex_lock(&parent->d_inode->i_mutex);
1488 new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1489 if (!IS_ERR(new_dentry)) {
1490 if (!new_dentry->d_inode) {
1491 error = config_item_set_name(item, "%s", new_name);
1493 d_add(new_dentry, NULL);
1494 d_move(item->dentry, new_dentry);
1497 d_delete(new_dentry);
1502 mutex_unlock(&parent->d_inode->i_mutex);
1503 up_write(&configfs_rename_sem);
1509 static int configfs_dir_open(struct inode *inode, struct file *file)
1511 struct dentry * dentry = file->f_path.dentry;
1512 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1515 mutex_lock(&dentry->d_inode->i_mutex);
1517 * Fake invisibility if dir belongs to a group/default groups hierarchy
1521 if (configfs_dirent_is_ready(parent_sd)) {
1522 file->private_data = configfs_new_dirent(parent_sd, NULL);
1523 if (IS_ERR(file->private_data))
1524 err = PTR_ERR(file->private_data);
1528 mutex_unlock(&dentry->d_inode->i_mutex);
1533 static int configfs_dir_close(struct inode *inode, struct file *file)
1535 struct dentry * dentry = file->f_path.dentry;
1536 struct configfs_dirent * cursor = file->private_data;
1538 mutex_lock(&dentry->d_inode->i_mutex);
1539 spin_lock(&configfs_dirent_lock);
1540 list_del_init(&cursor->s_sibling);
1541 spin_unlock(&configfs_dirent_lock);
1542 mutex_unlock(&dentry->d_inode->i_mutex);
1544 release_configfs_dirent(cursor);
1549 /* Relationship between s_mode and the DT_xxx types */
1550 static inline unsigned char dt_type(struct configfs_dirent *sd)
1552 return (sd->s_mode >> 12) & 15;
1555 static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
1557 struct dentry *dentry = filp->f_path.dentry;
1558 struct configfs_dirent * parent_sd = dentry->d_fsdata;
1559 struct configfs_dirent *cursor = filp->private_data;
1560 struct list_head *p, *q = &cursor->s_sibling;
1562 int i = filp->f_pos;
1566 ino = dentry->d_inode->i_ino;
1567 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1573 ino = parent_ino(dentry);
1574 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1580 if (filp->f_pos == 2) {
1581 spin_lock(&configfs_dirent_lock);
1582 list_move(q, &parent_sd->s_children);
1583 spin_unlock(&configfs_dirent_lock);
1585 for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
1586 struct configfs_dirent *next;
1590 next = list_entry(p, struct configfs_dirent,
1592 if (!next->s_element)
1595 name = configfs_get_name(next);
1598 ino = next->s_dentry->d_inode->i_ino;
1600 ino = iunique(configfs_sb, 2);
1602 if (filldir(dirent, name, len, filp->f_pos, ino,
1606 spin_lock(&configfs_dirent_lock);
1608 spin_unlock(&configfs_dirent_lock);
1616 static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
1618 struct dentry * dentry = file->f_path.dentry;
1620 mutex_lock(&dentry->d_inode->i_mutex);
1623 offset += file->f_pos;
1628 mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
1631 if (offset != file->f_pos) {
1632 file->f_pos = offset;
1633 if (file->f_pos >= 2) {
1634 struct configfs_dirent *sd = dentry->d_fsdata;
1635 struct configfs_dirent *cursor = file->private_data;
1636 struct list_head *p;
1637 loff_t n = file->f_pos - 2;
1639 spin_lock(&configfs_dirent_lock);
1640 list_del(&cursor->s_sibling);
1641 p = sd->s_children.next;
1642 while (n && p != &sd->s_children) {
1643 struct configfs_dirent *next;
1644 next = list_entry(p, struct configfs_dirent,
1646 if (next->s_element)
1650 list_add_tail(&cursor->s_sibling, p);
1651 spin_unlock(&configfs_dirent_lock);
1654 mutex_unlock(&dentry->d_inode->i_mutex);
1658 const struct file_operations configfs_dir_operations = {
1659 .open = configfs_dir_open,
1660 .release = configfs_dir_close,
1661 .llseek = configfs_dir_lseek,
1662 .read = generic_read_dir,
1663 .readdir = configfs_readdir,
1666 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1669 struct config_group *group = &subsys->su_group;
1671 struct dentry *dentry;
1672 struct configfs_dirent *sd;
1674 err = configfs_pin_fs();
1678 if (!group->cg_item.ci_name)
1679 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1681 sd = configfs_sb->s_root->d_fsdata;
1682 link_group(to_config_group(sd->s_element), group);
1684 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1687 name.name = group->cg_item.ci_name;
1688 name.len = strlen(name.name);
1689 name.hash = full_name_hash(name.name, name.len);
1692 dentry = d_alloc(configfs_sb->s_root, &name);
1694 d_add(dentry, NULL);
1696 err = configfs_attach_group(sd->s_element, &group->cg_item,
1702 spin_lock(&configfs_dirent_lock);
1703 configfs_dir_set_ready(dentry->d_fsdata);
1704 spin_unlock(&configfs_dirent_lock);
1708 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1711 unlink_group(group);
1712 configfs_release_fs();
1718 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1720 struct config_group *group = &subsys->su_group;
1721 struct dentry *dentry = group->cg_item.ci_dentry;
1723 if (dentry->d_parent != configfs_sb->s_root) {
1724 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1728 mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
1730 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
1731 mutex_lock(&configfs_symlink_mutex);
1732 spin_lock(&configfs_dirent_lock);
1733 if (configfs_detach_prep(dentry, NULL)) {
1734 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1736 spin_unlock(&configfs_dirent_lock);
1737 mutex_unlock(&configfs_symlink_mutex);
1738 configfs_detach_group(&group->cg_item);
1739 dentry->d_inode->i_flags |= S_DEAD;
1740 mutex_unlock(&dentry->d_inode->i_mutex);
1744 mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1748 unlink_group(group);
1749 configfs_release_fs();
1752 EXPORT_SYMBOL(configfs_register_subsystem);
1753 EXPORT_SYMBOL(configfs_unregister_subsystem);