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/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 }