fs/configfs/inode.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * inode.c - basic inode and dentry operations.
   4  *
   5  * Based on sysfs:
   6  *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
   7  *
   8  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
   9  *
  10  * Please see Documentation/filesystems/configfs.rst for more
  11  * information.
  12  */
  13
  14 #undef DEBUG
  15
  16 #include <linux/pagemap.h>
  17 #include <linux/namei.h>
  18 #include <linux/backing-dev.h>
  19 #include <linux/capability.h>
  20 #include <linux/sched.h>
  21 #include <linux/lockdep.h>
  22 #include <linux/slab.h>
  23
  24 #include <linux/configfs.h>
  25 #include "configfs_internal.h"
  26
  27 #ifdef CONFIG_LOCKDEP
  28 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  29 #endif
  30
  31 static const struct inode_operations configfs_inode_operations ={
  32         .setattr        = configfs_setattr,
  33 };
  34
  35 int configfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
  36                      struct iattr *iattr)
  37 {
  38         struct inode * inode = d_inode(dentry);
  39         struct configfs_dirent * sd = dentry->d_fsdata;
  40         struct iattr * sd_iattr;
  41         unsigned int ia_valid = iattr->ia_valid;
  42         int error;
  43
  44         if (!sd)
  45                 return -EINVAL;
  46
  47         sd_iattr = sd->s_iattr;
  48         if (!sd_iattr) {
  49                 /* setting attributes for the first time, allocate now */
  50                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  51                 if (!sd_iattr)
  52                         return -ENOMEM;
  53                 /* assign default attributes */
  54                 sd_iattr->ia_mode = sd->s_mode;
  55                 sd_iattr->ia_uid = GLOBAL_ROOT_UID;
  56                 sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  57                 sd_iattr->ia_atime = sd_iattr->ia_mtime =
  58                         sd_iattr->ia_ctime = current_time(inode);
  59                 sd->s_iattr = sd_iattr;
  60         }
  61         /* attributes were changed atleast once in past */
  62
  63         error = simple_setattr(idmap, dentry, iattr);
  64         if (error)
  65                 return error;
  66
  67         if (ia_valid & ATTR_UID)
  68                 sd_iattr->ia_uid = iattr->ia_uid;
  69         if (ia_valid & ATTR_GID)
  70                 sd_iattr->ia_gid = iattr->ia_gid;
  71         if (ia_valid & ATTR_ATIME)
  72                 sd_iattr->ia_atime = iattr->ia_atime;
  73         if (ia_valid & ATTR_MTIME)
  74                 sd_iattr->ia_mtime = iattr->ia_mtime;
  75         if (ia_valid & ATTR_CTIME)
  76                 sd_iattr->ia_ctime = iattr->ia_ctime;
  77         if (ia_valid & ATTR_MODE) {
  78                 umode_t mode = iattr->ia_mode;
  79
  80                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  81                         mode &= ~S_ISGID;
  82                 sd_iattr->ia_mode = sd->s_mode = mode;
  83         }
  84
  85         return error;
  86 }
  87
  88 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
  89 {
  90         inode->i_mode = mode;
  91         simple_inode_init_ts(inode);
  92 }
  93
  94 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
  95 {
  96         inode->i_mode = iattr->ia_mode;
  97         inode->i_uid = iattr->ia_uid;
  98         inode->i_gid = iattr->ia_gid;
  99         inode_set_atime_to_ts(inode, iattr->ia_atime);
 100         inode_set_mtime_to_ts(inode, iattr->ia_mtime);
 101         inode_set_ctime_to_ts(inode, iattr->ia_ctime);
 102 }
 103
 104 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 105                                  struct super_block *s)
 106 {
 107         struct inode * inode = new_inode(s);
 108         if (inode) {
 109                 inode->i_ino = get_next_ino();
 110                 inode->i_mapping->a_ops = &ram_aops;
 111                 inode->i_op = &configfs_inode_operations;
 112
 113                 if (sd->s_iattr) {
 114                         /* sysfs_dirent has non-default attributes
 115                          * get them for the new inode from persistent copy
 116                          * in sysfs_dirent
 117                          */
 118                         set_inode_attr(inode, sd->s_iattr);
 119                 } else
 120                         set_default_inode_attr(inode, mode);
 121         }
 122         return inode;
 123 }
 124
 125 #ifdef CONFIG_LOCKDEP
 126
 127 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 128                                           struct inode *inode)
 129 {
 130         int depth = sd->s_depth;
 131
 132         if (depth > 0) {
 133                 if (depth <= ARRAY_SIZE(default_group_class)) {
 134                         lockdep_set_class(&inode->i_rwsem,
 135                                           &default_group_class[depth - 1]);
 136                 } else {
 137                         /*
 138                          * In practice the maximum level of locking depth is
 139                          * already reached. Just inform about possible reasons.
 140                          */
 141                         pr_info("Too many levels of inodes for the locking correctness validator.\n");
 142                         pr_info("Spurious warnings may appear.\n");
 143                 }
 144         }
 145 }
 146
 147 #else /* CONFIG_LOCKDEP */
 148
 149 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 150                                           struct inode *inode)
 151 {
 152 }
 153
 154 #endif /* CONFIG_LOCKDEP */
 155
 156 struct inode *configfs_create(struct dentry *dentry, umode_t mode)
 157 {
 158         struct inode *inode = NULL;
 159         struct configfs_dirent *sd;
 160         struct inode *p_inode;
 161
 162         if (!dentry)
 163                 return ERR_PTR(-ENOENT);
 164
 165         if (d_really_is_positive(dentry))
 166                 return ERR_PTR(-EEXIST);
 167
 168         sd = dentry->d_fsdata;
 169         inode = configfs_new_inode(mode, sd, dentry->d_sb);
 170         if (!inode)
 171                 return ERR_PTR(-ENOMEM);
 172
 173         p_inode = d_inode(dentry->d_parent);
 174         inode_set_mtime_to_ts(p_inode, inode_set_ctime_current(p_inode));
 175         configfs_set_inode_lock_class(sd, inode);
 176         return inode;
 177 }
 178
 179 /*
 180  * Get the name for corresponding element represented by the given configfs_dirent
 181  */
 182 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 183 {
 184         struct configfs_attribute *attr;
 185
 186         BUG_ON(!sd || !sd->s_element);
 187
 188         /* These always have a dentry, so use that */
 189         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 190                 return sd->s_dentry->d_name.name;
 191
 192         if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
 193                 attr = sd->s_element;
 194                 return attr->ca_name;
 195         }
 196         return NULL;
 197 }
 198
 199
 200 /*
 201  * Unhashes the dentry corresponding to given configfs_dirent
 202  * Called with parent inode's i_mutex held.
 203  */
 204 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 205 {
 206         struct dentry * dentry = sd->s_dentry;
 207
 208         if (dentry) {
 209                 spin_lock(&dentry->d_lock);
 210                 if (simple_positive(dentry)) {
 211                         dget_dlock(dentry);
 212                         __d_drop(dentry);
 213                         spin_unlock(&dentry->d_lock);
 214                         simple_unlink(d_inode(parent), dentry);
 215                 } else
 216                         spin_unlock(&dentry->d_lock);
 217         }
 218 }