inode.c 7.3 KB

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  1. /*
  2. * inode.c - basic inode and dentry operations.
  3. *
  4. * sysfs is Copyright (c) 2001-3 Patrick Mochel
  5. *
  6. * Please see Documentation/filesystems/sysfs.txt for more information.
  7. */
  8. #undef DEBUG
  9. #include <linux/pagemap.h>
  10. #include <linux/namei.h>
  11. #include <linux/backing-dev.h>
  12. #include <linux/capability.h>
  13. #include <linux/errno.h>
  14. #include <asm/semaphore.h>
  15. #include "sysfs.h"
  16. extern struct super_block * sysfs_sb;
  17. static const struct address_space_operations sysfs_aops = {
  18. .readpage = simple_readpage,
  19. .prepare_write = simple_prepare_write,
  20. .commit_write = simple_commit_write
  21. };
  22. static struct backing_dev_info sysfs_backing_dev_info = {
  23. .ra_pages = 0, /* No readahead */
  24. .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  25. };
  26. static const struct inode_operations sysfs_inode_operations ={
  27. .setattr = sysfs_setattr,
  28. };
  29. void sysfs_delete_inode(struct inode *inode)
  30. {
  31. /* Free the shadowed directory inode operations */
  32. if (sysfs_is_shadowed_inode(inode)) {
  33. kfree(inode->i_op);
  34. inode->i_op = NULL;
  35. }
  36. return generic_delete_inode(inode);
  37. }
  38. int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
  39. {
  40. struct inode * inode = dentry->d_inode;
  41. struct sysfs_dirent * sd = dentry->d_fsdata;
  42. struct iattr * sd_iattr;
  43. unsigned int ia_valid = iattr->ia_valid;
  44. int error;
  45. if (!sd)
  46. return -EINVAL;
  47. sd_iattr = sd->s_iattr;
  48. error = inode_change_ok(inode, iattr);
  49. if (error)
  50. return error;
  51. error = inode_setattr(inode, iattr);
  52. if (error)
  53. return error;
  54. if (!sd_iattr) {
  55. /* setting attributes for the first time, allocate now */
  56. sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  57. if (!sd_iattr)
  58. return -ENOMEM;
  59. /* assign default attributes */
  60. sd_iattr->ia_mode = sd->s_mode;
  61. sd_iattr->ia_uid = 0;
  62. sd_iattr->ia_gid = 0;
  63. sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  64. sd->s_iattr = sd_iattr;
  65. }
  66. /* attributes were changed atleast once in past */
  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 = timespec_trunc(iattr->ia_atime,
  73. inode->i_sb->s_time_gran);
  74. if (ia_valid & ATTR_MTIME)
  75. sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
  76. inode->i_sb->s_time_gran);
  77. if (ia_valid & ATTR_CTIME)
  78. sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
  79. inode->i_sb->s_time_gran);
  80. if (ia_valid & ATTR_MODE) {
  81. umode_t mode = iattr->ia_mode;
  82. if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  83. mode &= ~S_ISGID;
  84. sd_iattr->ia_mode = sd->s_mode = mode;
  85. }
  86. return error;
  87. }
  88. static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
  89. {
  90. inode->i_mode = mode;
  91. inode->i_uid = 0;
  92. inode->i_gid = 0;
  93. inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  94. }
  95. static 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. /*
  105. * sysfs has a different i_mutex lock order behavior for i_mutex than other
  106. * filesystems; sysfs i_mutex is called in many places with subsystem locks
  107. * held. At the same time, many of the VFS locking rules do not apply to
  108. * sysfs at all (cross directory rename for example). To untangle this mess
  109. * (which gives false positives in lockdep), we're giving sysfs inodes their
  110. * own class for i_mutex.
  111. */
  112. static struct lock_class_key sysfs_inode_imutex_key;
  113. struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
  114. {
  115. struct inode * inode = new_inode(sysfs_sb);
  116. if (inode) {
  117. inode->i_blocks = 0;
  118. inode->i_mapping->a_ops = &sysfs_aops;
  119. inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
  120. inode->i_op = &sysfs_inode_operations;
  121. lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
  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 sysfs_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 sysfs_dirent * sd = dentry->d_fsdata;
  140. if ((inode = sysfs_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))
  160. dget(dentry); /* pin only directory dentry 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 sysfs_dirent
  168. */
  169. const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
  170. {
  171. struct attribute * attr;
  172. struct bin_attribute * bin_attr;
  173. struct sysfs_symlink * sl;
  174. BUG_ON(!sd || !sd->s_element);
  175. switch (sd->s_type) {
  176. case SYSFS_DIR:
  177. /* Always have a dentry so use that */
  178. return sd->s_dentry->d_name.name;
  179. case SYSFS_KOBJ_ATTR:
  180. attr = sd->s_element;
  181. return attr->name;
  182. case SYSFS_KOBJ_BIN_ATTR:
  183. bin_attr = sd->s_element;
  184. return bin_attr->attr.name;
  185. case SYSFS_KOBJ_LINK:
  186. sl = sd->s_element;
  187. return sl->link_name;
  188. }
  189. return NULL;
  190. }
  191. static inline void orphan_all_buffers(struct inode *node)
  192. {
  193. struct sysfs_buffer_collection *set;
  194. struct sysfs_buffer *buf;
  195. mutex_lock_nested(&node->i_mutex, I_MUTEX_CHILD);
  196. set = node->i_private;
  197. if (set) {
  198. list_for_each_entry(buf, &set->associates, associates) {
  199. down(&buf->sem);
  200. buf->orphaned = 1;
  201. up(&buf->sem);
  202. }
  203. }
  204. mutex_unlock(&node->i_mutex);
  205. }
  206. /*
  207. * Unhashes the dentry corresponding to given sysfs_dirent
  208. * Called with parent inode's i_mutex held.
  209. */
  210. void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
  211. {
  212. struct dentry * dentry = sd->s_dentry;
  213. struct inode *inode;
  214. if (dentry) {
  215. spin_lock(&dcache_lock);
  216. spin_lock(&dentry->d_lock);
  217. if (!(d_unhashed(dentry) && dentry->d_inode)) {
  218. inode = dentry->d_inode;
  219. spin_lock(&inode->i_lock);
  220. __iget(inode);
  221. spin_unlock(&inode->i_lock);
  222. dget_locked(dentry);
  223. __d_drop(dentry);
  224. spin_unlock(&dentry->d_lock);
  225. spin_unlock(&dcache_lock);
  226. simple_unlink(parent->d_inode, dentry);
  227. orphan_all_buffers(inode);
  228. iput(inode);
  229. } else {
  230. spin_unlock(&dentry->d_lock);
  231. spin_unlock(&dcache_lock);
  232. }
  233. }
  234. }
  235. int sysfs_hash_and_remove(struct dentry * dir, const char * name)
  236. {
  237. struct sysfs_dirent * sd;
  238. struct sysfs_dirent * parent_sd;
  239. int found = 0;
  240. if (!dir)
  241. return -ENOENT;
  242. if (dir->d_inode == NULL)
  243. /* no inode means this hasn't been made visible yet */
  244. return -ENOENT;
  245. parent_sd = dir->d_fsdata;
  246. mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
  247. list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
  248. if (!sd->s_element)
  249. continue;
  250. if (!strcmp(sysfs_get_name(sd), name)) {
  251. list_del_init(&sd->s_sibling);
  252. sysfs_drop_dentry(sd, dir);
  253. sysfs_put(sd);
  254. found = 1;
  255. break;
  256. }
  257. }
  258. mutex_unlock(&dir->d_inode->i_mutex);
  259. return found ? 0 : -ENOENT;
  260. }