xref: /openbmc/linux/fs/configfs/inode.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * inode.c - basic inode and dentry operations.
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 sysfs:
22  * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
23  *
24  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
25  *
26  * Please see Documentation/filesystems/configfs.txt for more information.
27  */
28 
29 #undef DEBUG
30 
31 #include <linux/pagemap.h>
32 #include <linux/namei.h>
33 #include <linux/backing-dev.h>
34 #include <linux/capability.h>
35 
36 #include <linux/configfs.h>
37 #include "configfs_internal.h"
38 
39 extern struct super_block * configfs_sb;
40 
41 static const struct address_space_operations configfs_aops = {
42 	.readpage	= simple_readpage,
43 	.prepare_write	= simple_prepare_write,
44 	.commit_write	= simple_commit_write
45 };
46 
47 static struct backing_dev_info configfs_backing_dev_info = {
48 	.ra_pages	= 0,	/* No readahead */
49 	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
50 };
51 
52 static const struct inode_operations configfs_inode_operations ={
53 	.setattr	= configfs_setattr,
54 };
55 
56 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
57 {
58 	struct inode * inode = dentry->d_inode;
59 	struct configfs_dirent * sd = dentry->d_fsdata;
60 	struct iattr * sd_iattr;
61 	unsigned int ia_valid = iattr->ia_valid;
62 	int error;
63 
64 	if (!sd)
65 		return -EINVAL;
66 
67 	sd_iattr = sd->s_iattr;
68 
69 	error = inode_change_ok(inode, iattr);
70 	if (error)
71 		return error;
72 
73 	error = inode_setattr(inode, iattr);
74 	if (error)
75 		return error;
76 
77 	if (!sd_iattr) {
78 		/* setting attributes for the first time, allocate now */
79 		sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
80 		if (!sd_iattr)
81 			return -ENOMEM;
82 		/* assign default attributes */
83 		sd_iattr->ia_mode = sd->s_mode;
84 		sd_iattr->ia_uid = 0;
85 		sd_iattr->ia_gid = 0;
86 		sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
87 		sd->s_iattr = sd_iattr;
88 	}
89 
90 	/* attributes were changed atleast once in past */
91 
92 	if (ia_valid & ATTR_UID)
93 		sd_iattr->ia_uid = iattr->ia_uid;
94 	if (ia_valid & ATTR_GID)
95 		sd_iattr->ia_gid = iattr->ia_gid;
96 	if (ia_valid & ATTR_ATIME)
97 		sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
98 						inode->i_sb->s_time_gran);
99 	if (ia_valid & ATTR_MTIME)
100 		sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
101 						inode->i_sb->s_time_gran);
102 	if (ia_valid & ATTR_CTIME)
103 		sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
104 						inode->i_sb->s_time_gran);
105 	if (ia_valid & ATTR_MODE) {
106 		umode_t mode = iattr->ia_mode;
107 
108 		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
109 			mode &= ~S_ISGID;
110 		sd_iattr->ia_mode = sd->s_mode = mode;
111 	}
112 
113 	return error;
114 }
115 
116 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
117 {
118 	inode->i_mode = mode;
119 	inode->i_uid = 0;
120 	inode->i_gid = 0;
121 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
122 }
123 
124 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
125 {
126 	inode->i_mode = iattr->ia_mode;
127 	inode->i_uid = iattr->ia_uid;
128 	inode->i_gid = iattr->ia_gid;
129 	inode->i_atime = iattr->ia_atime;
130 	inode->i_mtime = iattr->ia_mtime;
131 	inode->i_ctime = iattr->ia_ctime;
132 }
133 
134 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
135 {
136 	struct inode * inode = new_inode(configfs_sb);
137 	if (inode) {
138 		inode->i_blocks = 0;
139 		inode->i_mapping->a_ops = &configfs_aops;
140 		inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
141 		inode->i_op = &configfs_inode_operations;
142 
143 		if (sd->s_iattr) {
144 			/* sysfs_dirent has non-default attributes
145 			 * get them for the new inode from persistent copy
146 			 * in sysfs_dirent
147 			 */
148 			set_inode_attr(inode, sd->s_iattr);
149 		} else
150 			set_default_inode_attr(inode, mode);
151 	}
152 	return inode;
153 }
154 
155 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
156 {
157 	int error = 0;
158 	struct inode * inode = NULL;
159 	if (dentry) {
160 		if (!dentry->d_inode) {
161 			struct configfs_dirent *sd = dentry->d_fsdata;
162 			if ((inode = configfs_new_inode(mode, sd))) {
163 				if (dentry->d_parent && dentry->d_parent->d_inode) {
164 					struct inode *p_inode = dentry->d_parent->d_inode;
165 					p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
166 				}
167 				goto Proceed;
168 			}
169 			else
170 				error = -ENOMEM;
171 		} else
172 			error = -EEXIST;
173 	} else
174 		error = -ENOENT;
175 	goto Done;
176 
177  Proceed:
178 	if (init)
179 		error = init(inode);
180 	if (!error) {
181 		d_instantiate(dentry, inode);
182 		if (S_ISDIR(mode) || S_ISLNK(mode))
183 			dget(dentry);  /* pin link and directory dentries in core */
184 	} else
185 		iput(inode);
186  Done:
187 	return error;
188 }
189 
190 /*
191  * Get the name for corresponding element represented by the given configfs_dirent
192  */
193 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
194 {
195 	struct configfs_attribute *attr;
196 
197 	BUG_ON(!sd || !sd->s_element);
198 
199 	/* These always have a dentry, so use that */
200 	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
201 		return sd->s_dentry->d_name.name;
202 
203 	if (sd->s_type & CONFIGFS_ITEM_ATTR) {
204 		attr = sd->s_element;
205 		return attr->ca_name;
206 	}
207 	return NULL;
208 }
209 
210 
211 /*
212  * Unhashes the dentry corresponding to given configfs_dirent
213  * Called with parent inode's i_mutex held.
214  */
215 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
216 {
217 	struct dentry * dentry = sd->s_dentry;
218 
219 	if (dentry) {
220 		spin_lock(&dcache_lock);
221 		spin_lock(&dentry->d_lock);
222 		if (!(d_unhashed(dentry) && dentry->d_inode)) {
223 			dget_locked(dentry);
224 			__d_drop(dentry);
225 			spin_unlock(&dentry->d_lock);
226 			spin_unlock(&dcache_lock);
227 			simple_unlink(parent->d_inode, dentry);
228 		} else {
229 			spin_unlock(&dentry->d_lock);
230 			spin_unlock(&dcache_lock);
231 		}
232 	}
233 }
234 
235 void configfs_hash_and_remove(struct dentry * dir, const char * name)
236 {
237 	struct configfs_dirent * sd;
238 	struct configfs_dirent * parent_sd = dir->d_fsdata;
239 
240 	if (dir->d_inode == NULL)
241 		/* no inode means this hasn't been made visible yet */
242 		return;
243 
244 	mutex_lock(&dir->d_inode->i_mutex);
245 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
246 		if (!sd->s_element)
247 			continue;
248 		if (!strcmp(configfs_get_name(sd), name)) {
249 			list_del_init(&sd->s_sibling);
250 			configfs_drop_dentry(sd, dir);
251 			configfs_put(sd);
252 			break;
253 		}
254 	}
255 	mutex_unlock(&dir->d_inode->i_mutex);
256 }
257 
258 
259