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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 struct backing_dev_info configfs_backing_dev_info = {
 54         .name           = "configfs",
 55         .ra_pages       = 0,    /* No readahead */
 56         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
 57 };
 58 
 59 static const struct inode_operations configfs_inode_operations ={
 60         .setattr        = configfs_setattr,
 61 };
 62 
 63 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
 64 {
 65         struct inode * inode = dentry->d_inode;
 66         struct configfs_dirent * sd = dentry->d_fsdata;
 67         struct iattr * sd_iattr;
 68         unsigned int ia_valid = iattr->ia_valid;
 69         int error;
 70 
 71         if (!sd)
 72                 return -EINVAL;
 73 
 74         sd_iattr = sd->s_iattr;
 75         if (!sd_iattr) {
 76                 /* setting attributes for the first time, allocate now */
 77                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
 78                 if (!sd_iattr)
 79                         return -ENOMEM;
 80                 /* assign default attributes */
 81                 sd_iattr->ia_mode = sd->s_mode;
 82                 sd_iattr->ia_uid = GLOBAL_ROOT_UID;
 83                 sd_iattr->ia_gid = GLOBAL_ROOT_GID;
 84                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
 85                 sd->s_iattr = sd_iattr;
 86         }
 87         /* attributes were changed atleast once in past */
 88 
 89         error = simple_setattr(dentry, iattr);
 90         if (error)
 91                 return error;
 92 
 93         if (ia_valid & ATTR_UID)
 94                 sd_iattr->ia_uid = iattr->ia_uid;
 95         if (ia_valid & ATTR_GID)
 96                 sd_iattr->ia_gid = iattr->ia_gid;
 97         if (ia_valid & ATTR_ATIME)
 98                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
 99                                                 inode->i_sb->s_time_gran);
100         if (ia_valid & ATTR_MTIME)
101                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
102                                                 inode->i_sb->s_time_gran);
103         if (ia_valid & ATTR_CTIME)
104                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
105                                                 inode->i_sb->s_time_gran);
106         if (ia_valid & ATTR_MODE) {
107                 umode_t mode = iattr->ia_mode;
108 
109                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
110                         mode &= ~S_ISGID;
111                 sd_iattr->ia_mode = sd->s_mode = mode;
112         }
113 
114         return error;
115 }
116 
117 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
118 {
119         inode->i_mode = mode;
120         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
121 }
122 
123 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
124 {
125         inode->i_mode = iattr->ia_mode;
126         inode->i_uid = iattr->ia_uid;
127         inode->i_gid = iattr->ia_gid;
128         inode->i_atime = iattr->ia_atime;
129         inode->i_mtime = iattr->ia_mtime;
130         inode->i_ctime = iattr->ia_ctime;
131 }
132 
133 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
134                                  struct super_block *s)
135 {
136         struct inode * inode = new_inode(s);
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                         pr_info("Too many levels of inodes for the locking correctness validator.\n");
172                         pr_info("Spurious warnings may appear.\n");
173                 }
174         }
175 }
176 
177 #else /* CONFIG_LOCKDEP */
178 
179 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
180                                           struct inode *inode)
181 {
182 }
183 
184 #endif /* CONFIG_LOCKDEP */
185 
186 int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct inode *))
187 {
188         int error = 0;
189         struct inode *inode = NULL;
190         struct configfs_dirent *sd;
191         struct inode *p_inode;
192 
193         if (!dentry)
194                 return -ENOENT;
195 
196         if (dentry->d_inode)
197                 return -EEXIST;
198 
199         sd = dentry->d_fsdata;
200         inode = configfs_new_inode(mode, sd, dentry->d_sb);
201         if (!inode)
202                 return -ENOMEM;
203 
204         p_inode = dentry->d_parent->d_inode;
205         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
206         configfs_set_inode_lock_class(sd, inode);
207 
208         if (init) {
209                 error = init(inode);
210                 if (error) {
211                         iput(inode);
212                         return error;
213                 }
214         }
215         d_instantiate(dentry, inode);
216         if (S_ISDIR(mode) || S_ISLNK(mode))
217                 dget(dentry);  /* pin link and directory dentries in core */
218         return error;
219 }
220 
221 /*
222  * Get the name for corresponding element represented by the given configfs_dirent
223  */
224 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
225 {
226         struct configfs_attribute *attr;
227 
228         BUG_ON(!sd || !sd->s_element);
229 
230         /* These always have a dentry, so use that */
231         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
232                 return sd->s_dentry->d_name.name;
233 
234         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
235                 attr = sd->s_element;
236                 return attr->ca_name;
237         }
238         return NULL;
239 }
240 
241 
242 /*
243  * Unhashes the dentry corresponding to given configfs_dirent
244  * Called with parent inode's i_mutex held.
245  */
246 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
247 {
248         struct dentry * dentry = sd->s_dentry;
249 
250         if (dentry) {
251                 spin_lock(&dentry->d_lock);
252                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
253                         dget_dlock(dentry);
254                         __d_drop(dentry);
255                         spin_unlock(&dentry->d_lock);
256                         simple_unlink(parent->d_inode, dentry);
257                 } else
258                         spin_unlock(&dentry->d_lock);
259         }
260 }
261 
262 void configfs_hash_and_remove(struct dentry * dir, const char * name)
263 {
264         struct configfs_dirent * sd;
265         struct configfs_dirent * parent_sd = dir->d_fsdata;
266 
267         if (dir->d_inode == NULL)
268                 /* no inode means this hasn't been made visible yet */
269                 return;
270 
271         mutex_lock(&dir->d_inode->i_mutex);
272         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
273                 if (!sd->s_element)
274                         continue;
275                 if (!strcmp(configfs_get_name(sd), name)) {
276                         spin_lock(&configfs_dirent_lock);
277                         list_del_init(&sd->s_sibling);
278                         spin_unlock(&configfs_dirent_lock);
279                         configfs_drop_dentry(sd, dir);
280                         configfs_put(sd);
281                         break;
282                 }
283         }
284         mutex_unlock(&dir->d_inode->i_mutex);
285 }
286 
287 int __init configfs_inode_init(void)
288 {
289         return bdi_init(&configfs_backing_dev_info);
290 }
291 
292 void configfs_inode_exit(void)
293 {
294         bdi_destroy(&configfs_backing_dev_info);
295 }
296 

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