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

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