original development tree for Linux kernel GTP module; now long in mainline.
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configfs: Silence lockdep on mkdir() and rmdir() When attaching default groups (subdirs) of a new group (in mkdir() or in configfs_register()), configfs recursively takes inode's mutexes along the path from the parent of the new group to the default subdirs. This is needed to ensure that the VFS will not race with operations on these sub-dirs. This is safe for the following reasons: - the VFS allows one to lock first an inode and second one of its children (The lock subclasses for this pattern are respectively I_MUTEX_PARENT and I_MUTEX_CHILD); - from this rule any inode path can be recursively locked in descending order as long as it stays under a single mountpoint and does not follow symlinks. Unfortunately lockdep does not know (yet?) how to handle such recursion. I've tried to use Peter Zijlstra's lock_set_subclass() helper to upgrade i_mutexes from I_MUTEX_CHILD to I_MUTEX_PARENT when we know that we might recursively lock some of their descendant, but this usage does not seem to fit the purpose of lock_set_subclass() because it leads to several i_mutex locked with subclass I_MUTEX_PARENT by the same task. >From inside configfs it is not possible to serialize those recursive locking with a top-level one, because mkdir() and rmdir() are already called with inodes locked by the VFS. So using some mutex_lock_nest_lock() is not an option. I am proposing two solutions: 1) one that wraps recursive mutex_lock()s with lockdep_off()/lockdep_on(). 2) (as suggested earlier by Peter Zijlstra) one that puts the i_mutexes recursively locked in different classes based on their depth from the top-level config_group created. This induces an arbitrary limit (MAX_LOCK_DEPTH - 2 == 46) on the nesting of configfs default groups whenever lockdep is activated but this limit looks reasonably high. Unfortunately, this also isolates VFS operations on configfs default groups from the others and thus lowers the chances to detect locking issues. Nobody likes solution 1), which I can understand. This patch implements solution 2). However lockdep is still not happy with configfs_depend_item(). Next patch reworks the locking of configfs_depend_item() and finally makes lockdep happy. [ Note: This hides a few locking interactions with the VFS from lockdep. That was my big concern, because we like lockdep's protection. However, the current state always dumps a spurious warning. The locking is correct, so I tell people to ignore the warning and that we'll keep our eyes on the locking to make sure it stays correct. With this patch, we eliminate the warning. We do lose some of the lockdep protections, but this only means that we still have to keep our eyes on the locking. We're going to do that anyway. -- Joel ] Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
13 years ago
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
12 years ago
configfs: Silence lockdep on mkdir() and rmdir() When attaching default groups (subdirs) of a new group (in mkdir() or in configfs_register()), configfs recursively takes inode's mutexes along the path from the parent of the new group to the default subdirs. This is needed to ensure that the VFS will not race with operations on these sub-dirs. This is safe for the following reasons: - the VFS allows one to lock first an inode and second one of its children (The lock subclasses for this pattern are respectively I_MUTEX_PARENT and I_MUTEX_CHILD); - from this rule any inode path can be recursively locked in descending order as long as it stays under a single mountpoint and does not follow symlinks. Unfortunately lockdep does not know (yet?) how to handle such recursion. I've tried to use Peter Zijlstra's lock_set_subclass() helper to upgrade i_mutexes from I_MUTEX_CHILD to I_MUTEX_PARENT when we know that we might recursively lock some of their descendant, but this usage does not seem to fit the purpose of lock_set_subclass() because it leads to several i_mutex locked with subclass I_MUTEX_PARENT by the same task. >From inside configfs it is not possible to serialize those recursive locking with a top-level one, because mkdir() and rmdir() are already called with inodes locked by the VFS. So using some mutex_lock_nest_lock() is not an option. I am proposing two solutions: 1) one that wraps recursive mutex_lock()s with lockdep_off()/lockdep_on(). 2) (as suggested earlier by Peter Zijlstra) one that puts the i_mutexes recursively locked in different classes based on their depth from the top-level config_group created. This induces an arbitrary limit (MAX_LOCK_DEPTH - 2 == 46) on the nesting of configfs default groups whenever lockdep is activated but this limit looks reasonably high. Unfortunately, this also isolates VFS operations on configfs default groups from the others and thus lowers the chances to detect locking issues. Nobody likes solution 1), which I can understand. This patch implements solution 2). However lockdep is still not happy with configfs_depend_item(). Next patch reworks the locking of configfs_depend_item() and finally makes lockdep happy. [ Note: This hides a few locking interactions with the VFS from lockdep. That was my big concern, because we like lockdep's protection. However, the current state always dumps a spurious warning. The locking is correct, so I tell people to ignore the warning and that we'll keep our eyes on the locking to make sure it stays correct. With this patch, we eliminate the warning. We do lose some of the lockdep protections, but this only means that we still have to keep our eyes on the locking. We're going to do that anyway. -- Joel ] Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
13 years ago
configfs: Silence lockdep on mkdir() and rmdir() When attaching default groups (subdirs) of a new group (in mkdir() or in configfs_register()), configfs recursively takes inode's mutexes along the path from the parent of the new group to the default subdirs. This is needed to ensure that the VFS will not race with operations on these sub-dirs. This is safe for the following reasons: - the VFS allows one to lock first an inode and second one of its children (The lock subclasses for this pattern are respectively I_MUTEX_PARENT and I_MUTEX_CHILD); - from this rule any inode path can be recursively locked in descending order as long as it stays under a single mountpoint and does not follow symlinks. Unfortunately lockdep does not know (yet?) how to handle such recursion. I've tried to use Peter Zijlstra's lock_set_subclass() helper to upgrade i_mutexes from I_MUTEX_CHILD to I_MUTEX_PARENT when we know that we might recursively lock some of their descendant, but this usage does not seem to fit the purpose of lock_set_subclass() because it leads to several i_mutex locked with subclass I_MUTEX_PARENT by the same task. >From inside configfs it is not possible to serialize those recursive locking with a top-level one, because mkdir() and rmdir() are already called with inodes locked by the VFS. So using some mutex_lock_nest_lock() is not an option. I am proposing two solutions: 1) one that wraps recursive mutex_lock()s with lockdep_off()/lockdep_on(). 2) (as suggested earlier by Peter Zijlstra) one that puts the i_mutexes recursively locked in different classes based on their depth from the top-level config_group created. This induces an arbitrary limit (MAX_LOCK_DEPTH - 2 == 46) on the nesting of configfs default groups whenever lockdep is activated but this limit looks reasonably high. Unfortunately, this also isolates VFS operations on configfs default groups from the others and thus lowers the chances to detect locking issues. Nobody likes solution 1), which I can understand. This patch implements solution 2). However lockdep is still not happy with configfs_depend_item(). Next patch reworks the locking of configfs_depend_item() and finally makes lockdep happy. [ Note: This hides a few locking interactions with the VFS from lockdep. That was my big concern, because we like lockdep's protection. However, the current state always dumps a spurious warning. The locking is correct, so I tell people to ignore the warning and that we'll keep our eyes on the locking to make sure it stays correct. With this patch, we eliminate the warning. We do lose some of the lockdep protections, but this only means that we still have to keep our eyes on the locking. We're going to do that anyway. -- Joel ] Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
13 years ago
  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/configfs.txt for more
  27. * information.
  28. */
  29. #undef DEBUG
  30. #include <linux/pagemap.h>
  31. #include <linux/namei.h>
  32. #include <linux/backing-dev.h>
  33. #include <linux/capability.h>
  34. #include <linux/sched.h>
  35. #include <linux/lockdep.h>
  36. #include <linux/slab.h>
  37. #include <linux/configfs.h>
  38. #include "configfs_internal.h"
  39. #ifdef CONFIG_LOCKDEP
  40. static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  41. #endif
  42. static const struct address_space_operations configfs_aops = {
  43. .readpage = simple_readpage,
  44. .write_begin = simple_write_begin,
  45. .write_end = simple_write_end,
  46. };
  47. static struct backing_dev_info configfs_backing_dev_info = {
  48. .name = "configfs",
  49. .ra_pages = 0, /* No readahead */
  50. .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
  51. };
  52. static const struct inode_operations configfs_inode_operations ={
  53. .setattr = configfs_setattr,
  54. };
  55. int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  56. {
  57. struct inode * inode = dentry->d_inode;
  58. struct configfs_dirent * sd = dentry->d_fsdata;
  59. struct iattr * sd_iattr;
  60. unsigned int ia_valid = iattr->ia_valid;
  61. int error;
  62. if (!sd)
  63. return -EINVAL;
  64. sd_iattr = sd->s_iattr;
  65. if (!sd_iattr) {
  66. /* setting attributes for the first time, allocate now */
  67. sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  68. if (!sd_iattr)
  69. return -ENOMEM;
  70. /* assign default attributes */
  71. sd_iattr->ia_mode = sd->s_mode;
  72. sd_iattr->ia_uid = GLOBAL_ROOT_UID;
  73. sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  74. sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  75. sd->s_iattr = sd_iattr;
  76. }
  77. /* attributes were changed atleast once in past */
  78. error = simple_setattr(dentry, iattr);
  79. if (error)
  80. return error;
  81. if (ia_valid & ATTR_UID)
  82. sd_iattr->ia_uid = iattr->ia_uid;
  83. if (ia_valid & ATTR_GID)
  84. sd_iattr->ia_gid = iattr->ia_gid;
  85. if (ia_valid & ATTR_ATIME)
  86. sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  87. inode->i_sb->s_time_gran);
  88. if (ia_valid & ATTR_MTIME)
  89. sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
  90. inode->i_sb->s_time_gran);
  91. if (ia_valid & ATTR_CTIME)
  92. sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
  93. inode->i_sb->s_time_gran);
  94. if (ia_valid & ATTR_MODE) {
  95. umode_t mode = iattr->ia_mode;
  96. if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  97. mode &= ~S_ISGID;
  98. sd_iattr->ia_mode = sd->s_mode = mode;
  99. }
  100. return error;
  101. }
  102. static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
  103. {
  104. inode->i_mode = mode;
  105. inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  106. }
  107. static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
  108. {
  109. inode->i_mode = iattr->ia_mode;
  110. inode->i_uid = iattr->ia_uid;
  111. inode->i_gid = iattr->ia_gid;
  112. inode->i_atime = iattr->ia_atime;
  113. inode->i_mtime = iattr->ia_mtime;
  114. inode->i_ctime = iattr->ia_ctime;
  115. }
  116. struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
  117. struct super_block *s)
  118. {
  119. struct inode * inode = new_inode(s);
  120. if (inode) {
  121. inode->i_ino = get_next_ino();
  122. inode->i_mapping->a_ops = &configfs_aops;
  123. inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
  124. inode->i_op = &configfs_inode_operations;
  125. if (sd->s_iattr) {
  126. /* sysfs_dirent has non-default attributes
  127. * get them for the new inode from persistent copy
  128. * in sysfs_dirent
  129. */
  130. set_inode_attr(inode, sd->s_iattr);
  131. } else
  132. set_default_inode_attr(inode, mode);
  133. }
  134. return inode;
  135. }
  136. #ifdef CONFIG_LOCKDEP
  137. static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
  138. struct inode *inode)
  139. {
  140. int depth = sd->s_depth;
  141. if (depth > 0) {
  142. if (depth <= ARRAY_SIZE(default_group_class)) {
  143. lockdep_set_class(&inode->i_mutex,
  144. &default_group_class[depth - 1]);
  145. } else {
  146. /*
  147. * In practice the maximum level of locking depth is
  148. * already reached. Just inform about possible reasons.
  149. */
  150. printk(KERN_INFO "configfs: Too many levels of inodes"
  151. " for the locking correctness validator.\n");
  152. printk(KERN_INFO "Spurious warnings may appear.\n");
  153. }
  154. }
  155. }
  156. #else /* CONFIG_LOCKDEP */
  157. static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
  158. struct inode *inode)
  159. {
  160. }
  161. #endif /* CONFIG_LOCKDEP */
  162. int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct inode *))
  163. {
  164. int error = 0;
  165. struct inode *inode = NULL;
  166. struct configfs_dirent *sd;
  167. struct inode *p_inode;
  168. if (!dentry)
  169. return -ENOENT;
  170. if (dentry->d_inode)
  171. return -EEXIST;
  172. sd = dentry->d_fsdata;
  173. inode = configfs_new_inode(mode, sd, dentry->d_sb);
  174. if (!inode)
  175. return -ENOMEM;
  176. p_inode = dentry->d_parent->d_inode;
  177. p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
  178. configfs_set_inode_lock_class(sd, inode);
  179. if (init) {
  180. error = init(inode);
  181. if (error) {
  182. iput(inode);
  183. return error;
  184. }
  185. }
  186. d_instantiate(dentry, inode);
  187. if (S_ISDIR(mode) || S_ISLNK(mode))
  188. dget(dentry); /* pin link and directory dentries in core */
  189. return error;
  190. }
  191. /*
  192. * Get the name for corresponding element represented by the given configfs_dirent
  193. */
  194. const unsigned char * configfs_get_name(struct configfs_dirent *sd)
  195. {
  196. struct configfs_attribute *attr;
  197. BUG_ON(!sd || !sd->s_element);
  198. /* These always have a dentry, so use that */
  199. if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
  200. return sd->s_dentry->d_name.name;
  201. if (sd->s_type & CONFIGFS_ITEM_ATTR) {
  202. attr = sd->s_element;
  203. return attr->ca_name;
  204. }
  205. return NULL;
  206. }
  207. /*
  208. * Unhashes the dentry corresponding to given configfs_dirent
  209. * Called with parent inode's i_mutex held.
  210. */
  211. void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
  212. {
  213. struct dentry * dentry = sd->s_dentry;
  214. if (dentry) {
  215. spin_lock(&dentry->d_lock);
  216. if (!(d_unhashed(dentry) && dentry->d_inode)) {
  217. dget_dlock(dentry);
  218. __d_drop(dentry);
  219. spin_unlock(&dentry->d_lock);
  220. simple_unlink(parent->d_inode, dentry);
  221. } else
  222. spin_unlock(&dentry->d_lock);
  223. }
  224. }
  225. void configfs_hash_and_remove(struct dentry * dir, const char * name)
  226. {
  227. struct configfs_dirent * sd;
  228. struct configfs_dirent * parent_sd = dir->d_fsdata;
  229. if (dir->d_inode == NULL)
  230. /* no inode means this hasn't been made visible yet */
  231. return;
  232. mutex_lock(&dir->d_inode->i_mutex);
  233. list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
  234. if (!sd->s_element)
  235. continue;
  236. if (!strcmp(configfs_get_name(sd), name)) {
  237. spin_lock(&configfs_dirent_lock);
  238. list_del_init(&sd->s_sibling);
  239. spin_unlock(&configfs_dirent_lock);
  240. configfs_drop_dentry(sd, dir);
  241. configfs_put(sd);
  242. break;
  243. }
  244. }
  245. mutex_unlock(&dir->d_inode->i_mutex);
  246. }
  247. int __init configfs_inode_init(void)
  248. {
  249. return bdi_init(&configfs_backing_dev_info);
  250. }
  251. void configfs_inode_exit(void)
  252. {
  253. bdi_destroy(&configfs_backing_dev_info);
  254. }