1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * inode.c - basic inode and dentry operations.
4 *
5 * Based on sysfs:
6 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
7 *
8 * configfs Copyright (C) 2005 Oracle. All rights reserved.
9 *
10 * Please see Documentation/filesystems/configfs.rst for more
11 * information.
12 */
13
14#undef DEBUG
15
16#include <linux/pagemap.h>
17#include <linux/namei.h>
18#include <linux/backing-dev.h>
19#include <linux/capability.h>
20#include <linux/sched.h>
21#include <linux/lockdep.h>
22#include <linux/slab.h>
23
24#include <linux/configfs.h>
25#include "configfs_internal.h"
26
27#ifdef CONFIG_LOCKDEP
28static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
29#endif
30
31static const struct inode_operations configfs_inode_operations ={
32 .setattr = configfs_setattr,
33};
34
35int configfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
36 struct iattr *iattr)
37{
38 struct inode * inode = d_inode(dentry);
39 struct configfs_dirent * sd = dentry->d_fsdata;
40 struct iattr * sd_iattr;
41 unsigned int ia_valid = iattr->ia_valid;
42 int error;
43
44 if (!sd)
45 return -EINVAL;
46
47 sd_iattr = sd->s_iattr;
48 if (!sd_iattr) {
49 /* setting attributes for the first time, allocate now */
50 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
51 if (!sd_iattr)
52 return -ENOMEM;
53 /* assign default attributes */
54 sd_iattr->ia_mode = sd->s_mode;
55 sd_iattr->ia_uid = GLOBAL_ROOT_UID;
56 sd_iattr->ia_gid = GLOBAL_ROOT_GID;
57 sd_iattr->ia_atime = sd_iattr->ia_mtime =
58 sd_iattr->ia_ctime = current_time(inode);
59 sd->s_iattr = sd_iattr;
60 }
61 /* attributes were changed atleast once in past */
62
63 error = simple_setattr(idmap, dentry, iattr);
64 if (error)
65 return error;
66
67 if (ia_valid & ATTR_UID)
68 sd_iattr->ia_uid = iattr->ia_uid;
69 if (ia_valid & ATTR_GID)
70 sd_iattr->ia_gid = iattr->ia_gid;
71 if (ia_valid & ATTR_ATIME)
72 sd_iattr->ia_atime = iattr->ia_atime;
73 if (ia_valid & ATTR_MTIME)
74 sd_iattr->ia_mtime = iattr->ia_mtime;
75 if (ia_valid & ATTR_CTIME)
76 sd_iattr->ia_ctime = iattr->ia_ctime;
77 if (ia_valid & ATTR_MODE) {
78 umode_t mode = iattr->ia_mode;
79
80 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
81 mode &= ~S_ISGID;
82 sd_iattr->ia_mode = sd->s_mode = mode;
83 }
84
85 return error;
86}
87
88static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
89{
90 inode->i_mode = mode;
91 simple_inode_init_ts(inode);
92}
93
94static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
95{
96 inode->i_mode = iattr->ia_mode;
97 inode->i_uid = iattr->ia_uid;
98 inode->i_gid = iattr->ia_gid;
99 inode_set_atime_to_ts(inode, ts: iattr->ia_atime);
100 inode_set_mtime_to_ts(inode, ts: iattr->ia_mtime);
101 inode_set_ctime_to_ts(inode, ts: iattr->ia_ctime);
102}
103
104struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
105 struct super_block *s)
106{
107 struct inode * inode = new_inode(sb: s);
108 if (inode) {
109 inode->i_ino = get_next_ino();
110 inode->i_mapping->a_ops = &ram_aops;
111 inode->i_op = &configfs_inode_operations;
112
113 if (sd->s_iattr) {
114 /* sysfs_dirent has non-default attributes
115 * get them for the new inode from persistent copy
116 * in sysfs_dirent
117 */
118 set_inode_attr(inode, iattr: sd->s_iattr);
119 } else
120 set_default_inode_attr(inode, mode);
121 }
122 return inode;
123}
124
125#ifdef CONFIG_LOCKDEP
126
127static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
128 struct inode *inode)
129{
130 int depth = sd->s_depth;
131
132 if (depth > 0) {
133 if (depth <= ARRAY_SIZE(default_group_class)) {
134 lockdep_set_class(&inode->i_rwsem,
135 &default_group_class[depth - 1]);
136 } else {
137 /*
138 * In practice the maximum level of locking depth is
139 * already reached. Just inform about possible reasons.
140 */
141 pr_info("Too many levels of inodes for the locking correctness validator.\n");
142 pr_info("Spurious warnings may appear.\n");
143 }
144 }
145}
146
147#else /* CONFIG_LOCKDEP */
148
149static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
150 struct inode *inode)
151{
152}
153
154#endif /* CONFIG_LOCKDEP */
155
156struct inode *configfs_create(struct dentry *dentry, umode_t mode)
157{
158 struct inode *inode = NULL;
159 struct configfs_dirent *sd;
160 struct inode *p_inode;
161
162 if (!dentry)
163 return ERR_PTR(error: -ENOENT);
164
165 if (d_really_is_positive(dentry))
166 return ERR_PTR(error: -EEXIST);
167
168 sd = dentry->d_fsdata;
169 inode = configfs_new_inode(mode, sd, s: dentry->d_sb);
170 if (!inode)
171 return ERR_PTR(error: -ENOMEM);
172
173 p_inode = d_inode(dentry: dentry->d_parent);
174 inode_set_mtime_to_ts(inode: p_inode, ts: inode_set_ctime_current(inode: p_inode));
175 configfs_set_inode_lock_class(sd, inode);
176 return inode;
177}
178
179/*
180 * Get the name for corresponding element represented by the given configfs_dirent
181 */
182const unsigned char * configfs_get_name(struct configfs_dirent *sd)
183{
184 struct configfs_attribute *attr;
185
186 BUG_ON(!sd || !sd->s_element);
187
188 /* These always have a dentry, so use that */
189 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
190 return sd->s_dentry->d_name.name;
191
192 if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
193 attr = sd->s_element;
194 return attr->ca_name;
195 }
196 return NULL;
197}
198
199
200/*
201 * Unhashes the dentry corresponding to given configfs_dirent
202 * Called with parent inode's i_mutex held.
203 */
204void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
205{
206 struct dentry * dentry = sd->s_dentry;
207
208 if (dentry) {
209 spin_lock(lock: &dentry->d_lock);
210 if (simple_positive(dentry)) {
211 dget_dlock(dentry);
212 __d_drop(dentry);
213 spin_unlock(lock: &dentry->d_lock);
214 __simple_unlink(d_inode(dentry: parent), dentry);
215 dput(dentry);
216 } else
217 spin_unlock(lock: &dentry->d_lock);
218 }
219}
220

source code of linux/fs/configfs/inode.c