fs/configfs/inode.c

   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.rst 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 }