linux/fs/configfs/inode.c
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   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
  28static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  29#endif
  30
  31static const struct inode_operations configfs_inode_operations ={
  32        .setattr        = configfs_setattr,
  33};
  34
  35int configfs_setattr(struct user_namespace *mnt_userns, 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(mnt_userns, 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
  88static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
  89{
  90        inode->i_mode = mode;
  91        inode->i_atime = inode->i_mtime =
  92                inode->i_ctime = current_time(inode);
  93}
  94
  95static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
  96{
  97        inode->i_mode = iattr->ia_mode;
  98        inode->i_uid = iattr->ia_uid;
  99        inode->i_gid = iattr->ia_gid;
 100        inode->i_atime = iattr->ia_atime;
 101        inode->i_mtime = iattr->ia_mtime;
 102        inode->i_ctime = iattr->ia_ctime;
 103}
 104
 105struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 106                                 struct super_block *s)
 107{
 108        struct inode * inode = new_inode(s);
 109        if (inode) {
 110                inode->i_ino = get_next_ino();
 111                inode->i_mapping->a_ops = &ram_aops;
 112                inode->i_op = &configfs_inode_operations;
 113
 114                if (sd->s_iattr) {
 115                        /* sysfs_dirent has non-default attributes
 116                         * get them for the new inode from persistent copy
 117                         * in sysfs_dirent
 118                         */
 119                        set_inode_attr(inode, sd->s_iattr);
 120                } else
 121                        set_default_inode_attr(inode, mode);
 122        }
 123        return inode;
 124}
 125
 126#ifdef CONFIG_LOCKDEP
 127
 128static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 129                                          struct inode *inode)
 130{
 131        int depth = sd->s_depth;
 132
 133        if (depth > 0) {
 134                if (depth <= ARRAY_SIZE(default_group_class)) {
 135                        lockdep_set_class(&inode->i_rwsem,
 136                                          &default_group_class[depth - 1]);
 137                } else {
 138                        /*
 139                         * In practice the maximum level of locking depth is
 140                         * already reached. Just inform about possible reasons.
 141                         */
 142                        pr_info("Too many levels of inodes for the locking correctness validator.\n");
 143                        pr_info("Spurious warnings may appear.\n");
 144                }
 145        }
 146}
 147
 148#else /* CONFIG_LOCKDEP */
 149
 150static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 151                                          struct inode *inode)
 152{
 153}
 154
 155#endif /* CONFIG_LOCKDEP */
 156
 157struct inode *configfs_create(struct dentry *dentry, umode_t mode)
 158{
 159        struct inode *inode = NULL;
 160        struct configfs_dirent *sd;
 161        struct inode *p_inode;
 162
 163        if (!dentry)
 164                return ERR_PTR(-ENOENT);
 165
 166        if (d_really_is_positive(dentry))
 167                return ERR_PTR(-EEXIST);
 168
 169        sd = dentry->d_fsdata;
 170        inode = configfs_new_inode(mode, sd, dentry->d_sb);
 171        if (!inode)
 172                return ERR_PTR(-ENOMEM);
 173
 174        p_inode = d_inode(dentry->d_parent);
 175        p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
 176        configfs_set_inode_lock_class(sd, inode);
 177        return inode;
 178}
 179
 180/*
 181 * Get the name for corresponding element represented by the given configfs_dirent
 182 */
 183const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 184{
 185        struct configfs_attribute *attr;
 186
 187        BUG_ON(!sd || !sd->s_element);
 188
 189        /* These always have a dentry, so use that */
 190        if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 191                return sd->s_dentry->d_name.name;
 192
 193        if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
 194                attr = sd->s_element;
 195                return attr->ca_name;
 196        }
 197        return NULL;
 198}
 199
 200
 201/*
 202 * Unhashes the dentry corresponding to given configfs_dirent
 203 * Called with parent inode's i_mutex held.
 204 */
 205void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 206{
 207        struct dentry * dentry = sd->s_dentry;
 208
 209        if (dentry) {
 210                spin_lock(&dentry->d_lock);
 211                if (simple_positive(dentry)) {
 212                        dget_dlock(dentry);
 213                        __d_drop(dentry);
 214                        spin_unlock(&dentry->d_lock);
 215                        simple_unlink(d_inode(parent), dentry);
 216                } else
 217                        spin_unlock(&dentry->d_lock);
 218        }
 219}
 220
 221void configfs_hash_and_remove(struct dentry * dir, const char * name)
 222{
 223        struct configfs_dirent * sd;
 224        struct configfs_dirent * parent_sd = dir->d_fsdata;
 225
 226        if (d_really_is_negative(dir))
 227                /* no inode means this hasn't been made visible yet */
 228                return;
 229
 230        inode_lock(d_inode(dir));
 231        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 232                if (!sd->s_element)
 233                        continue;
 234                if (!strcmp(configfs_get_name(sd), name)) {
 235                        spin_lock(&configfs_dirent_lock);
 236                        list_del_init(&sd->s_sibling);
 237                        spin_unlock(&configfs_dirent_lock);
 238                        configfs_drop_dentry(sd, dir);
 239                        configfs_put(sd);
 240                        break;
 241                }
 242        }
 243        inode_unlock(d_inode(dir));
 244}
 245
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