xref: /openbmc/linux/fs/configfs/inode.c (revision b830f94f)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* -*- mode: c; c-basic-offset: 8; -*-
3  * vim: noexpandtab sw=8 ts=8 sts=0:
4  *
5  * inode.c - basic inode and dentry operations.
6  *
7  * Based on sysfs:
8  * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
9  *
10  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
11  *
12  * Please see Documentation/filesystems/configfs/configfs.txt for more
13  * information.
14  */
15 
16 #undef DEBUG
17 
18 #include <linux/pagemap.h>
19 #include <linux/namei.h>
20 #include <linux/backing-dev.h>
21 #include <linux/capability.h>
22 #include <linux/sched.h>
23 #include <linux/lockdep.h>
24 #include <linux/slab.h>
25 
26 #include <linux/configfs.h>
27 #include "configfs_internal.h"
28 
29 #ifdef CONFIG_LOCKDEP
30 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
31 #endif
32 
33 static const struct address_space_operations configfs_aops = {
34 	.readpage	= simple_readpage,
35 	.write_begin	= simple_write_begin,
36 	.write_end	= simple_write_end,
37 };
38 
39 static const struct inode_operations configfs_inode_operations ={
40 	.setattr	= configfs_setattr,
41 };
42 
43 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
44 {
45 	struct inode * inode = d_inode(dentry);
46 	struct configfs_dirent * sd = dentry->d_fsdata;
47 	struct iattr * sd_iattr;
48 	unsigned int ia_valid = iattr->ia_valid;
49 	int error;
50 
51 	if (!sd)
52 		return -EINVAL;
53 
54 	sd_iattr = sd->s_iattr;
55 	if (!sd_iattr) {
56 		/* setting attributes for the first time, allocate now */
57 		sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
58 		if (!sd_iattr)
59 			return -ENOMEM;
60 		/* assign default attributes */
61 		sd_iattr->ia_mode = sd->s_mode;
62 		sd_iattr->ia_uid = GLOBAL_ROOT_UID;
63 		sd_iattr->ia_gid = GLOBAL_ROOT_GID;
64 		sd_iattr->ia_atime = sd_iattr->ia_mtime =
65 			sd_iattr->ia_ctime = current_time(inode);
66 		sd->s_iattr = sd_iattr;
67 	}
68 	/* attributes were changed atleast once in past */
69 
70 	error = simple_setattr(dentry, iattr);
71 	if (error)
72 		return error;
73 
74 	if (ia_valid & ATTR_UID)
75 		sd_iattr->ia_uid = iattr->ia_uid;
76 	if (ia_valid & ATTR_GID)
77 		sd_iattr->ia_gid = iattr->ia_gid;
78 	if (ia_valid & ATTR_ATIME)
79 		sd_iattr->ia_atime = timespec64_trunc(iattr->ia_atime,
80 						      inode->i_sb->s_time_gran);
81 	if (ia_valid & ATTR_MTIME)
82 		sd_iattr->ia_mtime = timespec64_trunc(iattr->ia_mtime,
83 						      inode->i_sb->s_time_gran);
84 	if (ia_valid & ATTR_CTIME)
85 		sd_iattr->ia_ctime = timespec64_trunc(iattr->ia_ctime,
86 						      inode->i_sb->s_time_gran);
87 	if (ia_valid & ATTR_MODE) {
88 		umode_t mode = iattr->ia_mode;
89 
90 		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
91 			mode &= ~S_ISGID;
92 		sd_iattr->ia_mode = sd->s_mode = mode;
93 	}
94 
95 	return error;
96 }
97 
98 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
99 {
100 	inode->i_mode = mode;
101 	inode->i_atime = inode->i_mtime =
102 		inode->i_ctime = current_time(inode);
103 }
104 
105 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
106 {
107 	inode->i_mode = iattr->ia_mode;
108 	inode->i_uid = iattr->ia_uid;
109 	inode->i_gid = iattr->ia_gid;
110 	inode->i_atime = iattr->ia_atime;
111 	inode->i_mtime = iattr->ia_mtime;
112 	inode->i_ctime = iattr->ia_ctime;
113 }
114 
115 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
116 				 struct super_block *s)
117 {
118 	struct inode * inode = new_inode(s);
119 	if (inode) {
120 		inode->i_ino = get_next_ino();
121 		inode->i_mapping->a_ops = &configfs_aops;
122 		inode->i_op = &configfs_inode_operations;
123 
124 		if (sd->s_iattr) {
125 			/* sysfs_dirent has non-default attributes
126 			 * get them for the new inode from persistent copy
127 			 * in sysfs_dirent
128 			 */
129 			set_inode_attr(inode, sd->s_iattr);
130 		} else
131 			set_default_inode_attr(inode, mode);
132 	}
133 	return inode;
134 }
135 
136 #ifdef CONFIG_LOCKDEP
137 
138 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
139 					  struct inode *inode)
140 {
141 	int depth = sd->s_depth;
142 
143 	if (depth > 0) {
144 		if (depth <= ARRAY_SIZE(default_group_class)) {
145 			lockdep_set_class(&inode->i_rwsem,
146 					  &default_group_class[depth - 1]);
147 		} else {
148 			/*
149 			 * In practice the maximum level of locking depth is
150 			 * already reached. Just inform about possible reasons.
151 			 */
152 			pr_info("Too many levels of inodes for the locking correctness validator.\n");
153 			pr_info("Spurious warnings may appear.\n");
154 		}
155 	}
156 }
157 
158 #else /* CONFIG_LOCKDEP */
159 
160 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
161 					  struct inode *inode)
162 {
163 }
164 
165 #endif /* CONFIG_LOCKDEP */
166 
167 int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *))
168 {
169 	int error = 0;
170 	struct inode *inode = NULL;
171 	struct configfs_dirent *sd;
172 	struct inode *p_inode;
173 
174 	if (!dentry)
175 		return -ENOENT;
176 
177 	if (d_really_is_positive(dentry))
178 		return -EEXIST;
179 
180 	sd = dentry->d_fsdata;
181 	inode = configfs_new_inode(mode, sd, dentry->d_sb);
182 	if (!inode)
183 		return -ENOMEM;
184 
185 	p_inode = d_inode(dentry->d_parent);
186 	p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
187 	configfs_set_inode_lock_class(sd, inode);
188 
189 	init(inode);
190 	if (S_ISDIR(mode) || S_ISLNK(mode)) {
191 		/*
192 		 * ->symlink(), ->mkdir(), configfs_register_subsystem() or
193 		 * create_default_group() - already hashed.
194 		 */
195 		d_instantiate(dentry, inode);
196 		dget(dentry);  /* pin link and directory dentries in core */
197 	} else {
198 		/* ->lookup() */
199 		d_add(dentry, inode);
200 	}
201 	return error;
202 }
203 
204 /*
205  * Get the name for corresponding element represented by the given configfs_dirent
206  */
207 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
208 {
209 	struct configfs_attribute *attr;
210 
211 	BUG_ON(!sd || !sd->s_element);
212 
213 	/* These always have a dentry, so use that */
214 	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
215 		return sd->s_dentry->d_name.name;
216 
217 	if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
218 		attr = sd->s_element;
219 		return attr->ca_name;
220 	}
221 	return NULL;
222 }
223 
224 
225 /*
226  * Unhashes the dentry corresponding to given configfs_dirent
227  * Called with parent inode's i_mutex held.
228  */
229 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
230 {
231 	struct dentry * dentry = sd->s_dentry;
232 
233 	if (dentry) {
234 		spin_lock(&dentry->d_lock);
235 		if (simple_positive(dentry)) {
236 			dget_dlock(dentry);
237 			__d_drop(dentry);
238 			spin_unlock(&dentry->d_lock);
239 			simple_unlink(d_inode(parent), dentry);
240 		} else
241 			spin_unlock(&dentry->d_lock);
242 	}
243 }
244 
245 void configfs_hash_and_remove(struct dentry * dir, const char * name)
246 {
247 	struct configfs_dirent * sd;
248 	struct configfs_dirent * parent_sd = dir->d_fsdata;
249 
250 	if (d_really_is_negative(dir))
251 		/* no inode means this hasn't been made visible yet */
252 		return;
253 
254 	inode_lock(d_inode(dir));
255 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
256 		if (!sd->s_element)
257 			continue;
258 		if (!strcmp(configfs_get_name(sd), name)) {
259 			spin_lock(&configfs_dirent_lock);
260 			list_del_init(&sd->s_sibling);
261 			spin_unlock(&configfs_dirent_lock);
262 			configfs_drop_dentry(sd, dir);
263 			configfs_put(sd);
264 			break;
265 		}
266 	}
267 	inode_unlock(d_inode(dir));
268 }
269