]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - fs/configfs/item.c
Merge tag 'for-linus-20180922' of git://git.kernel.dk/linux-block
[mirror_ubuntu-eoan-kernel.git] / fs / configfs / item.c
1 /* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * item.c - library routines for handling generic config items
5 *
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.
10 *
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.
15 *
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.
20 *
21 * Based on kobject:
22 * kobject is Copyright (c) 2002-2003 Patrick Mochel
23 *
24 * configfs Copyright (C) 2005 Oracle. All rights reserved.
25 *
26 * Please see the file Documentation/filesystems/configfs/configfs.txt for
27 * critical information about using the config_item interface.
28 */
29
30 #include <linux/string.h>
31 #include <linux/module.h>
32 #include <linux/stat.h>
33 #include <linux/slab.h>
34
35 #include <linux/configfs.h>
36
37
38 static inline struct config_item *to_item(struct list_head *entry)
39 {
40 return container_of(entry, struct config_item, ci_entry);
41 }
42
43 /* Evil kernel */
44 static void config_item_release(struct kref *kref);
45
46 /**
47 * config_item_init - initialize item.
48 * @item: item in question.
49 */
50 static void config_item_init(struct config_item *item)
51 {
52 kref_init(&item->ci_kref);
53 INIT_LIST_HEAD(&item->ci_entry);
54 }
55
56 /**
57 * config_item_set_name - Set the name of an item
58 * @item: item.
59 * @fmt: The vsnprintf()'s format string.
60 *
61 * If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a
62 * dynamically allocated string that @item->ci_name points to.
63 * Otherwise, use the static @item->ci_namebuf array.
64 */
65 int config_item_set_name(struct config_item *item, const char *fmt, ...)
66 {
67 int limit = CONFIGFS_ITEM_NAME_LEN;
68 int need;
69 va_list args;
70 char *name;
71
72 /*
73 * First, try the static array
74 */
75 va_start(args, fmt);
76 need = vsnprintf(item->ci_namebuf, limit, fmt, args);
77 va_end(args);
78 if (need < limit)
79 name = item->ci_namebuf;
80 else {
81 va_start(args, fmt);
82 name = kvasprintf(GFP_KERNEL, fmt, args);
83 va_end(args);
84 if (!name)
85 return -EFAULT;
86 }
87
88 /* Free the old name, if necessary. */
89 if (item->ci_name && item->ci_name != item->ci_namebuf)
90 kfree(item->ci_name);
91
92 /* Now, set the new name */
93 item->ci_name = name;
94 return 0;
95 }
96 EXPORT_SYMBOL(config_item_set_name);
97
98 void config_item_init_type_name(struct config_item *item,
99 const char *name,
100 const struct config_item_type *type)
101 {
102 config_item_set_name(item, "%s", name);
103 item->ci_type = type;
104 config_item_init(item);
105 }
106 EXPORT_SYMBOL(config_item_init_type_name);
107
108 void config_group_init_type_name(struct config_group *group, const char *name,
109 const struct config_item_type *type)
110 {
111 config_item_set_name(&group->cg_item, "%s", name);
112 group->cg_item.ci_type = type;
113 config_group_init(group);
114 }
115 EXPORT_SYMBOL(config_group_init_type_name);
116
117 struct config_item *config_item_get(struct config_item *item)
118 {
119 if (item)
120 kref_get(&item->ci_kref);
121 return item;
122 }
123 EXPORT_SYMBOL(config_item_get);
124
125 struct config_item *config_item_get_unless_zero(struct config_item *item)
126 {
127 if (item && kref_get_unless_zero(&item->ci_kref))
128 return item;
129 return NULL;
130 }
131 EXPORT_SYMBOL(config_item_get_unless_zero);
132
133 static void config_item_cleanup(struct config_item *item)
134 {
135 const struct config_item_type *t = item->ci_type;
136 struct config_group *s = item->ci_group;
137 struct config_item *parent = item->ci_parent;
138
139 pr_debug("config_item %s: cleaning up\n", config_item_name(item));
140 if (item->ci_name != item->ci_namebuf)
141 kfree(item->ci_name);
142 item->ci_name = NULL;
143 if (t && t->ct_item_ops && t->ct_item_ops->release)
144 t->ct_item_ops->release(item);
145 if (s)
146 config_group_put(s);
147 if (parent)
148 config_item_put(parent);
149 }
150
151 static void config_item_release(struct kref *kref)
152 {
153 config_item_cleanup(container_of(kref, struct config_item, ci_kref));
154 }
155
156 /**
157 * config_item_put - decrement refcount for item.
158 * @item: item.
159 *
160 * Decrement the refcount, and if 0, call config_item_cleanup().
161 */
162 void config_item_put(struct config_item *item)
163 {
164 if (item)
165 kref_put(&item->ci_kref, config_item_release);
166 }
167 EXPORT_SYMBOL(config_item_put);
168
169 /**
170 * config_group_init - initialize a group for use
171 * @group: config_group
172 */
173 void config_group_init(struct config_group *group)
174 {
175 config_item_init(&group->cg_item);
176 INIT_LIST_HEAD(&group->cg_children);
177 INIT_LIST_HEAD(&group->default_groups);
178 }
179 EXPORT_SYMBOL(config_group_init);
180
181 /**
182 * config_group_find_item - search for item in group.
183 * @group: group we're looking in.
184 * @name: item's name.
185 *
186 * Iterate over @group->cg_list, looking for a matching config_item.
187 * If matching item is found take a reference and return the item.
188 * Caller must have locked group via @group->cg_subsys->su_mtx.
189 */
190 struct config_item *config_group_find_item(struct config_group *group,
191 const char *name)
192 {
193 struct list_head *entry;
194 struct config_item *ret = NULL;
195
196 list_for_each(entry, &group->cg_children) {
197 struct config_item *item = to_item(entry);
198 if (config_item_name(item) &&
199 !strcmp(config_item_name(item), name)) {
200 ret = config_item_get(item);
201 break;
202 }
203 }
204 return ret;
205 }
206 EXPORT_SYMBOL(config_group_find_item);