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TOMOYO Linux Cross Reference
Linux/fs/configfs/inode.c

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  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
 44 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
 45 #endif
 46 
 47 static 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 
 53 static const struct inode_operations configfs_inode_operations ={
 54         .setattr        = configfs_setattr,
 55 };
 56 
 57 int 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 =
 79                         sd_iattr->ia_ctime = current_time(inode);
 80                 sd->s_iattr = sd_iattr;
 81         }
 82         /* attributes were changed atleast once in past */
 83 
 84         error = simple_setattr(dentry, iattr);
 85         if (error)
 86                 return error;
 87 
 88         if (ia_valid & ATTR_UID)
 89                 sd_iattr->ia_uid = iattr->ia_uid;
 90         if (ia_valid & ATTR_GID)
 91                 sd_iattr->ia_gid = iattr->ia_gid;
 92         if (ia_valid & ATTR_ATIME)
 93                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
 94                                                 inode->i_sb->s_time_gran);
 95         if (ia_valid & ATTR_MTIME)
 96                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 97                                                 inode->i_sb->s_time_gran);
 98         if (ia_valid & ATTR_CTIME)
 99                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
100                                                 inode->i_sb->s_time_gran);
101         if (ia_valid & ATTR_MODE) {
102                 umode_t mode = iattr->ia_mode;
103 
104                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
105                         mode &= ~S_ISGID;
106                 sd_iattr->ia_mode = sd->s_mode = mode;
107         }
108 
109         return error;
110 }
111 
112 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
113 {
114         inode->i_mode = mode;
115         inode->i_atime = inode->i_mtime =
116                 inode->i_ctime = current_time(inode);
117 }
118 
119 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
120 {
121         inode->i_mode = iattr->ia_mode;
122         inode->i_uid = iattr->ia_uid;
123         inode->i_gid = iattr->ia_gid;
124         inode->i_atime = iattr->ia_atime;
125         inode->i_mtime = iattr->ia_mtime;
126         inode->i_ctime = iattr->ia_ctime;
127 }
128 
129 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
130                                  struct super_block *s)
131 {
132         struct inode * inode = new_inode(s);
133         if (inode) {
134                 inode->i_ino = get_next_ino();
135                 inode->i_mapping->a_ops = &configfs_aops;
136                 inode->i_op = &configfs_inode_operations;
137 
138                 if (sd->s_iattr) {
139                         /* sysfs_dirent has non-default attributes
140                          * get them for the new inode from persistent copy
141                          * in sysfs_dirent
142                          */
143                         set_inode_attr(inode, sd->s_iattr);
144                 } else
145                         set_default_inode_attr(inode, mode);
146         }
147         return inode;
148 }
149 
150 #ifdef CONFIG_LOCKDEP
151 
152 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
153                                           struct inode *inode)
154 {
155         int depth = sd->s_depth;
156 
157         if (depth > 0) {
158                 if (depth <= ARRAY_SIZE(default_group_class)) {
159                         lockdep_set_class(&inode->i_rwsem,
160                                           &default_group_class[depth - 1]);
161                 } else {
162                         /*
163                          * In practice the maximum level of locking depth is
164                          * already reached. Just inform about possible reasons.
165                          */
166                         pr_info("Too many levels of inodes for the locking correctness validator.\n");
167                         pr_info("Spurious warnings may appear.\n");
168                 }
169         }
170 }
171 
172 #else /* CONFIG_LOCKDEP */
173 
174 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
175                                           struct inode *inode)
176 {
177 }
178 
179 #endif /* CONFIG_LOCKDEP */
180 
181 int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *))
182 {
183         int error = 0;
184         struct inode *inode = NULL;
185         struct configfs_dirent *sd;
186         struct inode *p_inode;
187 
188         if (!dentry)
189                 return -ENOENT;
190 
191         if (d_really_is_positive(dentry))
192                 return -EEXIST;
193 
194         sd = dentry->d_fsdata;
195         inode = configfs_new_inode(mode, sd, dentry->d_sb);
196         if (!inode)
197                 return -ENOMEM;
198 
199         p_inode = d_inode(dentry->d_parent);
200         p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
201         configfs_set_inode_lock_class(sd, inode);
202 
203         init(inode);
204         if (S_ISDIR(mode) || S_ISLNK(mode)) {
205                 /*
206                  * ->symlink(), ->mkdir(), configfs_register_subsystem() or
207                  * create_default_group() - already hashed.
208                  */
209                 d_instantiate(dentry, inode);
210                 dget(dentry);  /* pin link and directory dentries in core */
211         } else {
212                 /* ->lookup() */
213                 d_add(dentry, inode);
214         }
215         return error;
216 }
217 
218 /*
219  * Get the name for corresponding element represented by the given configfs_dirent
220  */
221 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
222 {
223         struct configfs_attribute *attr;
224 
225         BUG_ON(!sd || !sd->s_element);
226 
227         /* These always have a dentry, so use that */
228         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
229                 return sd->s_dentry->d_name.name;
230 
231         if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
232                 attr = sd->s_element;
233                 return attr->ca_name;
234         }
235         return NULL;
236 }
237 
238 
239 /*
240  * Unhashes the dentry corresponding to given configfs_dirent
241  * Called with parent inode's i_mutex held.
242  */
243 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
244 {
245         struct dentry * dentry = sd->s_dentry;
246 
247         if (dentry) {
248                 spin_lock(&dentry->d_lock);
249                 if (simple_positive(dentry)) {
250                         dget_dlock(dentry);
251                         __d_drop(dentry);
252                         spin_unlock(&dentry->d_lock);
253                         simple_unlink(d_inode(parent), dentry);
254                 } else
255                         spin_unlock(&dentry->d_lock);
256         }
257 }
258 
259 void configfs_hash_and_remove(struct dentry * dir, const char * name)
260 {
261         struct configfs_dirent * sd;
262         struct configfs_dirent * parent_sd = dir->d_fsdata;
263 
264         if (d_really_is_negative(dir))
265                 /* no inode means this hasn't been made visible yet */
266                 return;
267 
268         inode_lock(d_inode(dir));
269         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
270                 if (!sd->s_element)
271                         continue;
272                 if (!strcmp(configfs_get_name(sd), name)) {
273                         spin_lock(&configfs_dirent_lock);
274                         list_del_init(&sd->s_sibling);
275                         spin_unlock(&configfs_dirent_lock);
276                         configfs_drop_dentry(sd, dir);
277                         configfs_put(sd);
278                         break;
279                 }
280         }
281         inode_unlock(d_inode(dir));
282 }
283 

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