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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.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 #include <linux/sched.h>
 36 #include <linux/lockdep.h>
 37 #include <linux/slab.h>
 38 
 39 #include <linux/configfs.h>
 40 #include "configfs_internal.h"
 41 
 42 #ifdef CONFIG_LOCKDEP
 43 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
 44 #endif
 45 
 46 extern struct super_block * configfs_sb;
 47 
 48 static const struct address_space_operations configfs_aops = {
 49         .readpage       = simple_readpage,
 50         .write_begin    = simple_write_begin,
 51         .write_end      = simple_write_end,
 52 };
 53 
 54 static struct backing_dev_info configfs_backing_dev_info = {
 55         .name           = "configfs",
 56         .ra_pages       = 0,    /* No readahead */
 57         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
 58 };
 59 
 60 static const struct inode_operations configfs_inode_operations ={
 61         .setattr        = configfs_setattr,
 62 };
 63 
 64 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
 65 {
 66         struct inode * inode = dentry->d_inode;
 67         struct configfs_dirent * sd = dentry->d_fsdata;
 68         struct iattr * sd_iattr;
 69         unsigned int ia_valid = iattr->ia_valid;
 70         int error;
 71 
 72         if (!sd)
 73                 return -EINVAL;
 74 
 75         sd_iattr = sd->s_iattr;
 76         if (!sd_iattr) {
 77                 /* setting attributes for the first time, allocate now */
 78                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
 79                 if (!sd_iattr)
 80                         return -ENOMEM;
 81                 /* assign default attributes */
 82                 sd_iattr->ia_mode = sd->s_mode;
 83                 sd_iattr->ia_uid = 0;
 84                 sd_iattr->ia_gid = 0;
 85                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
 86                 sd->s_iattr = sd_iattr;
 87         }
 88         /* attributes were changed atleast once in past */
 89 
 90         error = simple_setattr(dentry, iattr);
 91         if (error)
 92                 return error;
 93 
 94         if (ia_valid & ATTR_UID)
 95                 sd_iattr->ia_uid = iattr->ia_uid;
 96         if (ia_valid & ATTR_GID)
 97                 sd_iattr->ia_gid = iattr->ia_gid;
 98         if (ia_valid & ATTR_ATIME)
 99                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
100                                                 inode->i_sb->s_time_gran);
101         if (ia_valid & ATTR_MTIME)
102                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
103                                                 inode->i_sb->s_time_gran);
104         if (ia_valid & ATTR_CTIME)
105                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
106                                                 inode->i_sb->s_time_gran);
107         if (ia_valid & ATTR_MODE) {
108                 umode_t mode = iattr->ia_mode;
109 
110                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
111                         mode &= ~S_ISGID;
112                 sd_iattr->ia_mode = sd->s_mode = mode;
113         }
114 
115         return error;
116 }
117 
118 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
119 {
120         inode->i_mode = mode;
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_ino = get_next_ino();
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 #ifdef CONFIG_LOCKDEP
156 
157 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
158                                           struct inode *inode)
159 {
160         int depth = sd->s_depth;
161 
162         if (depth > 0) {
163                 if (depth <= ARRAY_SIZE(default_group_class)) {
164                         lockdep_set_class(&inode->i_mutex,
165                                           &default_group_class[depth - 1]);
166                 } else {
167                         /*
168                          * In practice the maximum level of locking depth is
169                          * already reached. Just inform about possible reasons.
170                          */
171                         printk(KERN_INFO "configfs: Too many levels of inodes"
172                                " for the locking correctness validator.\n");
173                         printk(KERN_INFO "Spurious warnings may appear.\n");
174                 }
175         }
176 }
177 
178 #else /* CONFIG_LOCKDEP */
179 
180 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
181                                           struct inode *inode)
182 {
183 }
184 
185 #endif /* CONFIG_LOCKDEP */
186 
187 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
188 {
189         int error = 0;
190         struct inode * inode = NULL;
191         if (dentry) {
192                 if (!dentry->d_inode) {
193                         struct configfs_dirent *sd = dentry->d_fsdata;
194                         if ((inode = configfs_new_inode(mode, sd))) {
195                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
196                                         struct inode *p_inode = dentry->d_parent->d_inode;
197                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
198                                 }
199                                 configfs_set_inode_lock_class(sd, inode);
200                                 goto Proceed;
201                         }
202                         else
203                                 error = -ENOMEM;
204                 } else
205                         error = -EEXIST;
206         } else
207                 error = -ENOENT;
208         goto Done;
209 
210  Proceed:
211         if (init)
212                 error = init(inode);
213         if (!error) {
214                 d_instantiate(dentry, inode);
215                 if (S_ISDIR(mode) || S_ISLNK(mode))
216                         dget(dentry);  /* pin link and directory dentries in core */
217         } else
218                 iput(inode);
219  Done:
220         return error;
221 }
222 
223 /*
224  * Get the name for corresponding element represented by the given configfs_dirent
225  */
226 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
227 {
228         struct configfs_attribute *attr;
229 
230         BUG_ON(!sd || !sd->s_element);
231 
232         /* These always have a dentry, so use that */
233         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
234                 return sd->s_dentry->d_name.name;
235 
236         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
237                 attr = sd->s_element;
238                 return attr->ca_name;
239         }
240         return NULL;
241 }
242 
243 
244 /*
245  * Unhashes the dentry corresponding to given configfs_dirent
246  * Called with parent inode's i_mutex held.
247  */
248 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
249 {
250         struct dentry * dentry = sd->s_dentry;
251 
252         if (dentry) {
253                 spin_lock(&dentry->d_lock);
254                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
255                         dget_dlock(dentry);
256                         __d_drop(dentry);
257                         spin_unlock(&dentry->d_lock);
258                         simple_unlink(parent->d_inode, dentry);
259                 } else
260                         spin_unlock(&dentry->d_lock);
261         }
262 }
263 
264 void configfs_hash_and_remove(struct dentry * dir, const char * name)
265 {
266         struct configfs_dirent * sd;
267         struct configfs_dirent * parent_sd = dir->d_fsdata;
268 
269         if (dir->d_inode == NULL)
270                 /* no inode means this hasn't been made visible yet */
271                 return;
272 
273         mutex_lock(&dir->d_inode->i_mutex);
274         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
275                 if (!sd->s_element)
276                         continue;
277                 if (!strcmp(configfs_get_name(sd), name)) {
278                         spin_lock(&configfs_dirent_lock);
279                         list_del_init(&sd->s_sibling);
280                         spin_unlock(&configfs_dirent_lock);
281                         configfs_drop_dentry(sd, dir);
282                         configfs_put(sd);
283                         break;
284                 }
285         }
286         mutex_unlock(&dir->d_inode->i_mutex);
287 }
288 
289 int __init configfs_inode_init(void)
290 {
291         return bdi_init(&configfs_backing_dev_info);
292 }
293 
294 void __exit configfs_inode_exit(void)
295 {
296         bdi_destroy(&configfs_backing_dev_info);
297 }
298 

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