fs/configfs/inode.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * inode.c - basic inode and dentry operations.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public
  17  * License along with this program; if not, write to the
  18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19  * Boston, MA 021110-1307, USA.
  20  *
  21  * Based on sysfs:
  22  *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
  23  *
  24  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  25  *
  26  * Please see Documentation/filesystems/configfs.txt for more information.
  27  */
  28
  29 #undef DEBUG
  30
  31 #include <linux/pagemap.h>
  32 #include <linux/namei.h>
  33 #include <linux/backing-dev.h>
  34
  35 #include <linux/configfs.h>
  36 #include "configfs_internal.h"
  37
  38 extern struct super_block * configfs_sb;
  39
  40 static struct address_space_operations configfs_aops = {
  41         .readpage       = simple_readpage,
  42         .prepare_write  = simple_prepare_write,
  43         .commit_write   = simple_commit_write
  44 };
  45
  46 static struct backing_dev_info configfs_backing_dev_info = {
  47         .ra_pages       = 0,    /* No readahead */
  48         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  49 };
  50
  51 struct inode * configfs_new_inode(mode_t mode)
  52 {
  53         struct inode * inode = new_inode(configfs_sb);
  54         if (inode) {
  55                 inode->i_mode = mode;
  56                 inode->i_uid = 0;
  57                 inode->i_gid = 0;
  58                 inode->i_blksize = PAGE_CACHE_SIZE;
  59                 inode->i_blocks = 0;
  60                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  61                 inode->i_mapping->a_ops = &configfs_aops;
  62                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
  63         }
  64         return inode;
  65 }
  66
  67 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
  68 {
  69         int error = 0;
  70         struct inode * inode = NULL;
  71         if (dentry) {
  72                 if (!dentry->d_inode) {
  73                         if ((inode = configfs_new_inode(mode))) {
  74                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
  75                                         struct inode *p_inode = dentry->d_parent->d_inode;
  76                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
  77                                 }
  78                                 goto Proceed;
  79                         }
  80                         else
  81                                 error = -ENOMEM;
  82                 } else
  83                         error = -EEXIST;
  84         } else
  85                 error = -ENOENT;
  86         goto Done;
  87
  88  Proceed:
  89         if (init)
  90                 error = init(inode);
  91         if (!error) {
  92                 d_instantiate(dentry, inode);
  93                 if (S_ISDIR(mode) || S_ISLNK(mode))
  94                         dget(dentry);  /* pin link and directory dentries in core */
  95         } else
  96                 iput(inode);
  97  Done:
  98         return error;
  99 }
 100
 101 /*
 102  * Get the name for corresponding element represented by the given configfs_dirent
 103  */
 104 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 105 {
 106         struct attribute * attr;
 107
 108         if (!sd || !sd->s_element)
 109                 BUG();
 110
 111         /* These always have a dentry, so use that */
 112         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 113                 return sd->s_dentry->d_name.name;
 114
 115         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 116                 attr = sd->s_element;
 117                 return attr->name;
 118         }
 119         return NULL;
 120 }
 121
 122
 123 /*
 124  * Unhashes the dentry corresponding to given configfs_dirent
 125  * Called with parent inode's i_mutex held.
 126  */
 127 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 128 {
 129         struct dentry * dentry = sd->s_dentry;
 130
 131         if (dentry) {
 132                 spin_lock(&dcache_lock);
 133                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 134                         dget_locked(dentry);
 135                         __d_drop(dentry);
 136                         spin_unlock(&dcache_lock);
 137                         simple_unlink(parent->d_inode, dentry);
 138                 } else
 139                         spin_unlock(&dcache_lock);
 140         }
 141 }
 142
 143 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 144 {
 145         struct configfs_dirent * sd;
 146         struct configfs_dirent * parent_sd = dir->d_fsdata;
 147
 148         mutex_lock(&dir->d_inode->i_mutex);
 149         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 150                 if (!sd->s_element)
 151                         continue;
 152                 if (!strcmp(configfs_get_name(sd), name)) {
 153                         list_del_init(&sd->s_sibling);
 154                         configfs_drop_dentry(sd, dir);
 155                         configfs_put(sd);
 156                         break;
 157                 }
 158         }
 159         mutex_unlock(&dir->d_inode->i_mutex);
 160 }
 161
 162