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 } 161 162 163