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Linux/fs/configfs/inode.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /* -*- mode: c; c-basic-offset: 8; -*-
  3  * vim: noexpandtab sw=8 ts=8 sts=0:
  4  *
  5  * inode.c - basic inode and dentry operations.
  6  *
  7  * Based on sysfs:
  8  *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
  9  *
 10  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
 11  *
 12  * Please see Documentation/filesystems/configfs/configfs.txt for more
 13  * information.
 14  */
 15 
 16 #undef DEBUG
 17 
 18 #include <linux/pagemap.h>
 19 #include <linux/namei.h>
 20 #include <linux/backing-dev.h>
 21 #include <linux/capability.h>
 22 #include <linux/sched.h>
 23 #include <linux/lockdep.h>
 24 #include <linux/slab.h>
 25 
 26 #include <linux/configfs.h>
 27 #include "configfs_internal.h"
 28 
 29 #ifdef CONFIG_LOCKDEP
 30 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
 31 #endif
 32 
 33 static const struct address_space_operations configfs_aops = {
 34         .readpage       = simple_readpage,
 35         .write_begin    = simple_write_begin,
 36         .write_end      = simple_write_end,
 37 };
 38 
 39 static const struct inode_operations configfs_inode_operations ={
 40         .setattr        = configfs_setattr,
 41 };
 42 
 43 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
 44 {
 45         struct inode * inode = d_inode(dentry);
 46         struct configfs_dirent * sd = dentry->d_fsdata;
 47         struct iattr * sd_iattr;
 48         unsigned int ia_valid = iattr->ia_valid;
 49         int error;
 50 
 51         if (!sd)
 52                 return -EINVAL;
 53 
 54         sd_iattr = sd->s_iattr;
 55         if (!sd_iattr) {
 56                 /* setting attributes for the first time, allocate now */
 57                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
 58                 if (!sd_iattr)
 59                         return -ENOMEM;
 60                 /* assign default attributes */
 61                 sd_iattr->ia_mode = sd->s_mode;
 62                 sd_iattr->ia_uid = GLOBAL_ROOT_UID;
 63                 sd_iattr->ia_gid = GLOBAL_ROOT_GID;
 64                 sd_iattr->ia_atime = sd_iattr->ia_mtime =
 65                         sd_iattr->ia_ctime = current_time(inode);
 66                 sd->s_iattr = sd_iattr;
 67         }
 68         /* attributes were changed atleast once in past */
 69 
 70         error = simple_setattr(dentry, iattr);
 71         if (error)
 72                 return error;
 73 
 74         if (ia_valid & ATTR_UID)
 75                 sd_iattr->ia_uid = iattr->ia_uid;
 76         if (ia_valid & ATTR_GID)
 77                 sd_iattr->ia_gid = iattr->ia_gid;
 78         if (ia_valid & ATTR_ATIME)
 79                 sd_iattr->ia_atime = timespec64_trunc(iattr->ia_atime,
 80                                                       inode->i_sb->s_time_gran);
 81         if (ia_valid & ATTR_MTIME)
 82                 sd_iattr->ia_mtime = timespec64_trunc(iattr->ia_mtime,
 83                                                       inode->i_sb->s_time_gran);
 84         if (ia_valid & ATTR_CTIME)
 85                 sd_iattr->ia_ctime = timespec64_trunc(iattr->ia_ctime,
 86                                                       inode->i_sb->s_time_gran);
 87         if (ia_valid & ATTR_MODE) {
 88                 umode_t mode = iattr->ia_mode;
 89 
 90                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 91                         mode &= ~S_ISGID;
 92                 sd_iattr->ia_mode = sd->s_mode = mode;
 93         }
 94 
 95         return error;
 96 }
 97 
 98 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
 99 {
100         inode->i_mode = mode;
101         inode->i_atime = inode->i_mtime =
102                 inode->i_ctime = current_time(inode);
103 }
104 
105 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
106 {
107         inode->i_mode = iattr->ia_mode;
108         inode->i_uid = iattr->ia_uid;
109         inode->i_gid = iattr->ia_gid;
110         inode->i_atime = iattr->ia_atime;
111         inode->i_mtime = iattr->ia_mtime;
112         inode->i_ctime = iattr->ia_ctime;
113 }
114 
115 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
116                                  struct super_block *s)
117 {
118         struct inode * inode = new_inode(s);
119         if (inode) {
120                 inode->i_ino = get_next_ino();
121                 inode->i_mapping->a_ops = &configfs_aops;
122                 inode->i_op = &configfs_inode_operations;
123 
124                 if (sd->s_iattr) {
125                         /* sysfs_dirent has non-default attributes
126                          * get them for the new inode from persistent copy
127                          * in sysfs_dirent
128                          */
129                         set_inode_attr(inode, sd->s_iattr);
130                 } else
131                         set_default_inode_attr(inode, mode);
132         }
133         return inode;
134 }
135 
136 #ifdef CONFIG_LOCKDEP
137 
138 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
139                                           struct inode *inode)
140 {
141         int depth = sd->s_depth;
142 
143         if (depth > 0) {
144                 if (depth <= ARRAY_SIZE(default_group_class)) {
145                         lockdep_set_class(&inode->i_rwsem,
146                                           &default_group_class[depth - 1]);
147                 } else {
148                         /*
149                          * In practice the maximum level of locking depth is
150                          * already reached. Just inform about possible reasons.
151                          */
152                         pr_info("Too many levels of inodes for the locking correctness validator.\n");
153                         pr_info("Spurious warnings may appear.\n");
154                 }
155         }
156 }
157 
158 #else /* CONFIG_LOCKDEP */
159 
160 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
161                                           struct inode *inode)
162 {
163 }
164 
165 #endif /* CONFIG_LOCKDEP */
166 
167 int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *))
168 {
169         int error = 0;
170         struct inode *inode = NULL;
171         struct configfs_dirent *sd;
172         struct inode *p_inode;
173 
174         if (!dentry)
175                 return -ENOENT;
176 
177         if (d_really_is_positive(dentry))
178                 return -EEXIST;
179 
180         sd = dentry->d_fsdata;
181         inode = configfs_new_inode(mode, sd, dentry->d_sb);
182         if (!inode)
183                 return -ENOMEM;
184 
185         p_inode = d_inode(dentry->d_parent);
186         p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
187         configfs_set_inode_lock_class(sd, inode);
188 
189         init(inode);
190         if (S_ISDIR(mode) || S_ISLNK(mode)) {
191                 /*
192                  * ->symlink(), ->mkdir(), configfs_register_subsystem() or
193                  * create_default_group() - already hashed.
194                  */
195                 d_instantiate(dentry, inode);
196                 dget(dentry);  /* pin link and directory dentries in core */
197         } else {
198                 /* ->lookup() */
199                 d_add(dentry, inode);
200         }
201         return error;
202 }
203 
204 /*
205  * Get the name for corresponding element represented by the given configfs_dirent
206  */
207 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
208 {
209         struct configfs_attribute *attr;
210 
211         BUG_ON(!sd || !sd->s_element);
212 
213         /* These always have a dentry, so use that */
214         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
215                 return sd->s_dentry->d_name.name;
216 
217         if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
218                 attr = sd->s_element;
219                 return attr->ca_name;
220         }
221         return NULL;
222 }
223 
224 
225 /*
226  * Unhashes the dentry corresponding to given configfs_dirent
227  * Called with parent inode's i_mutex held.
228  */
229 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
230 {
231         struct dentry * dentry = sd->s_dentry;
232 
233         if (dentry) {
234                 spin_lock(&dentry->d_lock);
235                 if (simple_positive(dentry)) {
236                         dget_dlock(dentry);
237                         __d_drop(dentry);
238                         spin_unlock(&dentry->d_lock);
239                         simple_unlink(d_inode(parent), dentry);
240                 } else
241                         spin_unlock(&dentry->d_lock);
242         }
243 }
244 
245 void configfs_hash_and_remove(struct dentry * dir, const char * name)
246 {
247         struct configfs_dirent * sd;
248         struct configfs_dirent * parent_sd = dir->d_fsdata;
249 
250         if (d_really_is_negative(dir))
251                 /* no inode means this hasn't been made visible yet */
252                 return;
253 
254         inode_lock(d_inode(dir));
255         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
256                 if (!sd->s_element)
257                         continue;
258                 if (!strcmp(configfs_get_name(sd), name)) {
259                         spin_lock(&configfs_dirent_lock);
260                         list_del_init(&sd->s_sibling);
261                         spin_unlock(&configfs_dirent_lock);
262                         configfs_drop_dentry(sd, dir);
263                         configfs_put(sd);
264                         break;
265                 }
266         }
267         inode_unlock(d_inode(dir));
268 }
269 

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