inode.c 6.7 KB

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  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. #undef DEBUG
  29. #include <linux/pagemap.h>
  30. #include <linux/namei.h>
  31. #include <linux/backing-dev.h>
  32. #include <linux/capability.h>
  33. #include <linux/configfs.h>
  34. #include "configfs_internal.h"
  35. extern struct super_block * configfs_sb;
  36. static const struct address_space_operations configfs_aops = {
  37. .readpage = simple_readpage,
  38. .prepare_write = simple_prepare_write,
  39. .commit_write = simple_commit_write
  40. };
  41. static struct backing_dev_info configfs_backing_dev_info = {
  42. .ra_pages = 0, /* No readahead */
  43. .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  44. };
  45. static const struct inode_operations configfs_inode_operations ={
  46. .setattr = configfs_setattr,
  47. };
  48. int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  49. {
  50. struct inode * inode = dentry->d_inode;
  51. struct configfs_dirent * sd = dentry->d_fsdata;
  52. struct iattr * sd_iattr;
  53. unsigned int ia_valid = iattr->ia_valid;
  54. int error;
  55. if (!sd)
  56. return -EINVAL;
  57. sd_iattr = sd->s_iattr;
  58. error = inode_change_ok(inode, iattr);
  59. if (error)
  60. return error;
  61. error = inode_setattr(inode, iattr);
  62. if (error)
  63. return error;
  64. if (!sd_iattr) {
  65. /* setting attributes for the first time, allocate now */
  66. sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  67. if (!sd_iattr)
  68. return -ENOMEM;
  69. /* assign default attributes */
  70. sd_iattr->ia_mode = sd->s_mode;
  71. sd_iattr->ia_uid = 0;
  72. sd_iattr->ia_gid = 0;
  73. sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  74. sd->s_iattr = sd_iattr;
  75. }
  76. /* attributes were changed atleast once in past */
  77. if (ia_valid & ATTR_UID)
  78. sd_iattr->ia_uid = iattr->ia_uid;
  79. if (ia_valid & ATTR_GID)
  80. sd_iattr->ia_gid = iattr->ia_gid;
  81. if (ia_valid & ATTR_ATIME)
  82. sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  83. inode->i_sb->s_time_gran);
  84. if (ia_valid & ATTR_MTIME)
  85. sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
  86. inode->i_sb->s_time_gran);
  87. if (ia_valid & ATTR_CTIME)
  88. sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
  89. inode->i_sb->s_time_gran);
  90. if (ia_valid & ATTR_MODE) {
  91. umode_t mode = iattr->ia_mode;
  92. if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  93. mode &= ~S_ISGID;
  94. sd_iattr->ia_mode = sd->s_mode = mode;
  95. }
  96. return error;
  97. }
  98. static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
  99. {
  100. inode->i_mode = mode;
  101. inode->i_uid = 0;
  102. inode->i_gid = 0;
  103. inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  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. struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
  115. {
  116. struct inode * inode = new_inode(configfs_sb);
  117. if (inode) {
  118. inode->i_blocks = 0;
  119. inode->i_mapping->a_ops = &configfs_aops;
  120. inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
  121. inode->i_op = &configfs_inode_operations;
  122. if (sd->s_iattr) {
  123. /* sysfs_dirent has non-default attributes
  124. * get them for the new inode from persistent copy
  125. * in sysfs_dirent
  126. */
  127. set_inode_attr(inode, sd->s_iattr);
  128. } else
  129. set_default_inode_attr(inode, mode);
  130. }
  131. return inode;
  132. }
  133. int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
  134. {
  135. int error = 0;
  136. struct inode * inode = NULL;
  137. if (dentry) {
  138. if (!dentry->d_inode) {
  139. struct configfs_dirent *sd = dentry->d_fsdata;
  140. if ((inode = configfs_new_inode(mode, sd))) {
  141. if (dentry->d_parent && dentry->d_parent->d_inode) {
  142. struct inode *p_inode = dentry->d_parent->d_inode;
  143. p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
  144. }
  145. goto Proceed;
  146. }
  147. else
  148. error = -ENOMEM;
  149. } else
  150. error = -EEXIST;
  151. } else
  152. error = -ENOENT;
  153. goto Done;
  154. Proceed:
  155. if (init)
  156. error = init(inode);
  157. if (!error) {
  158. d_instantiate(dentry, inode);
  159. if (S_ISDIR(mode) || S_ISLNK(mode))
  160. dget(dentry); /* pin link and directory dentries in core */
  161. } else
  162. iput(inode);
  163. Done:
  164. return error;
  165. }
  166. /*
  167. * Get the name for corresponding element represented by the given configfs_dirent
  168. */
  169. const unsigned char * configfs_get_name(struct configfs_dirent *sd)
  170. {
  171. struct configfs_attribute *attr;
  172. BUG_ON(!sd || !sd->s_element);
  173. /* These always have a dentry, so use that */
  174. if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
  175. return sd->s_dentry->d_name.name;
  176. if (sd->s_type & CONFIGFS_ITEM_ATTR) {
  177. attr = sd->s_element;
  178. return attr->ca_name;
  179. }
  180. return NULL;
  181. }
  182. /*
  183. * Unhashes the dentry corresponding to given configfs_dirent
  184. * Called with parent inode's i_mutex held.
  185. */
  186. void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
  187. {
  188. struct dentry * dentry = sd->s_dentry;
  189. if (dentry) {
  190. spin_lock(&dcache_lock);
  191. spin_lock(&dentry->d_lock);
  192. if (!(d_unhashed(dentry) && dentry->d_inode)) {
  193. dget_locked(dentry);
  194. __d_drop(dentry);
  195. spin_unlock(&dentry->d_lock);
  196. spin_unlock(&dcache_lock);
  197. simple_unlink(parent->d_inode, dentry);
  198. } else {
  199. spin_unlock(&dentry->d_lock);
  200. spin_unlock(&dcache_lock);
  201. }
  202. }
  203. }
  204. void configfs_hash_and_remove(struct dentry * dir, const char * name)
  205. {
  206. struct configfs_dirent * sd;
  207. struct configfs_dirent * parent_sd = dir->d_fsdata;
  208. if (dir->d_inode == NULL)
  209. /* no inode means this hasn't been made visible yet */
  210. return;
  211. mutex_lock(&dir->d_inode->i_mutex);
  212. list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
  213. if (!sd->s_element)
  214. continue;
  215. if (!strcmp(configfs_get_name(sd), name)) {
  216. list_del_init(&sd->s_sibling);
  217. configfs_drop_dentry(sd, dir);
  218. configfs_put(sd);
  219. break;
  220. }
  221. }
  222. mutex_unlock(&dir->d_inode->i_mutex);
  223. }