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/configfs.txt for more
27 * information.
28 */
29
30#undef DEBUG
31
32#include <linux/pagemap.h>
33#include <linux/namei.h>
34#include <linux/backing-dev.h>
35#include <linux/capability.h>
36#include <linux/sched.h>
37#include <linux/lockdep.h>
38#include <linux/slab.h>
39
40#include <linux/configfs.h>
41#include "configfs_internal.h"
42
43#ifdef CONFIG_LOCKDEP
44static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
45#endif
46
47static const struct address_space_operations configfs_aops = {
48	.readpage	= simple_readpage,
49	.write_begin	= simple_write_begin,
50	.write_end	= simple_write_end,
51};
52
53static const struct inode_operations configfs_inode_operations ={
54	.setattr	= configfs_setattr,
55};
56
57int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
58{
59	struct inode * inode = d_inode(dentry);
60	struct configfs_dirent * sd = dentry->d_fsdata;
61	struct iattr * sd_iattr;
62	unsigned int ia_valid = iattr->ia_valid;
63	int error;
64
65	if (!sd)
66		return -EINVAL;
67
68	sd_iattr = sd->s_iattr;
69	if (!sd_iattr) {
70		/* setting attributes for the first time, allocate now */
71		sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
72		if (!sd_iattr)
73			return -ENOMEM;
74		/* assign default attributes */
75		sd_iattr->ia_mode = sd->s_mode;
76		sd_iattr->ia_uid = GLOBAL_ROOT_UID;
77		sd_iattr->ia_gid = GLOBAL_ROOT_GID;
78		sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
79		sd->s_iattr = sd_iattr;
80	}
81	/* attributes were changed atleast once in past */
82
83	error = simple_setattr(dentry, iattr);
84	if (error)
85		return error;
86
87	if (ia_valid & ATTR_UID)
88		sd_iattr->ia_uid = iattr->ia_uid;
89	if (ia_valid & ATTR_GID)
90		sd_iattr->ia_gid = iattr->ia_gid;
91	if (ia_valid & ATTR_ATIME)
92		sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
93						inode->i_sb->s_time_gran);
94	if (ia_valid & ATTR_MTIME)
95		sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
96						inode->i_sb->s_time_gran);
97	if (ia_valid & ATTR_CTIME)
98		sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
99						inode->i_sb->s_time_gran);
100	if (ia_valid & ATTR_MODE) {
101		umode_t mode = iattr->ia_mode;
102
103		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
104			mode &= ~S_ISGID;
105		sd_iattr->ia_mode = sd->s_mode = mode;
106	}
107
108	return error;
109}
110
111static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
112{
113	inode->i_mode = mode;
114	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
115}
116
117static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
118{
119	inode->i_mode = iattr->ia_mode;
120	inode->i_uid = iattr->ia_uid;
121	inode->i_gid = iattr->ia_gid;
122	inode->i_atime = iattr->ia_atime;
123	inode->i_mtime = iattr->ia_mtime;
124	inode->i_ctime = iattr->ia_ctime;
125}
126
127struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
128				 struct super_block *s)
129{
130	struct inode * inode = new_inode(s);
131	if (inode) {
132		inode->i_ino = get_next_ino();
133		inode->i_mapping->a_ops = &configfs_aops;
134		inode->i_op = &configfs_inode_operations;
135
136		if (sd->s_iattr) {
137			/* sysfs_dirent has non-default attributes
138			 * get them for the new inode from persistent copy
139			 * in sysfs_dirent
140			 */
141			set_inode_attr(inode, sd->s_iattr);
142		} else
143			set_default_inode_attr(inode, mode);
144	}
145	return inode;
146}
147
148#ifdef CONFIG_LOCKDEP
149
150static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
151					  struct inode *inode)
152{
153	int depth = sd->s_depth;
154
155	if (depth > 0) {
156		if (depth <= ARRAY_SIZE(default_group_class)) {
157			lockdep_set_class(&inode->i_mutex,
158					  &default_group_class[depth - 1]);
159		} else {
160			/*
161			 * In practice the maximum level of locking depth is
162			 * already reached. Just inform about possible reasons.
163			 */
164			pr_info("Too many levels of inodes for the locking correctness validator.\n");
165			pr_info("Spurious warnings may appear.\n");
166		}
167	}
168}
169
170#else /* CONFIG_LOCKDEP */
171
172static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
173					  struct inode *inode)
174{
175}
176
177#endif /* CONFIG_LOCKDEP */
178
179int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *))
180{
181	int error = 0;
182	struct inode *inode = NULL;
183	struct configfs_dirent *sd;
184	struct inode *p_inode;
185
186	if (!dentry)
187		return -ENOENT;
188
189	if (d_really_is_positive(dentry))
190		return -EEXIST;
191
192	sd = dentry->d_fsdata;
193	inode = configfs_new_inode(mode, sd, dentry->d_sb);
194	if (!inode)
195		return -ENOMEM;
196
197	p_inode = d_inode(dentry->d_parent);
198	p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
199	configfs_set_inode_lock_class(sd, inode);
200
201	init(inode);
202	d_instantiate(dentry, inode);
203	if (S_ISDIR(mode) || S_ISLNK(mode))
204		dget(dentry);  /* pin link and directory dentries in core */
205	return error;
206}
207
208/*
209 * Get the name for corresponding element represented by the given configfs_dirent
210 */
211const unsigned char * configfs_get_name(struct configfs_dirent *sd)
212{
213	struct configfs_attribute *attr;
214
215	BUG_ON(!sd || !sd->s_element);
216
217	/* These always have a dentry, so use that */
218	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
219		return sd->s_dentry->d_name.name;
220
221	if (sd->s_type & CONFIGFS_ITEM_ATTR) {
222		attr = sd->s_element;
223		return attr->ca_name;
224	}
225	return NULL;
226}
227
228
229/*
230 * Unhashes the dentry corresponding to given configfs_dirent
231 * Called with parent inode's i_mutex held.
232 */
233void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
234{
235	struct dentry * dentry = sd->s_dentry;
236
237	if (dentry) {
238		spin_lock(&dentry->d_lock);
239		if (!d_unhashed(dentry) && d_really_is_positive(dentry)) {
240			dget_dlock(dentry);
241			__d_drop(dentry);
242			spin_unlock(&dentry->d_lock);
243			simple_unlink(d_inode(parent), dentry);
244		} else
245			spin_unlock(&dentry->d_lock);
246	}
247}
248
249void configfs_hash_and_remove(struct dentry * dir, const char * name)
250{
251	struct configfs_dirent * sd;
252	struct configfs_dirent * parent_sd = dir->d_fsdata;
253
254	if (d_really_is_negative(dir))
255		/* no inode means this hasn't been made visible yet */
256		return;
257
258	mutex_lock(&d_inode(dir)->i_mutex);
259	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
260		if (!sd->s_element)
261			continue;
262		if (!strcmp(configfs_get_name(sd), name)) {
263			spin_lock(&configfs_dirent_lock);
264			list_del_init(&sd->s_sibling);
265			spin_unlock(&configfs_dirent_lock);
266			configfs_drop_dentry(sd, dir);
267			configfs_put(sd);
268			break;
269		}
270	}
271	mutex_unlock(&d_inode(dir)->i_mutex);
272}
273