1 /* 2 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2, or (at your option) 7 * any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; see the file COPYING. If not, write to 16 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 17 */ 18 19 #include <linux/dcache.h> 20 #include <linux/fs.h> 21 #include <linux/gfp.h> 22 #include <linux/init.h> 23 #include <linux/module.h> 24 #include <linux/mount.h> 25 #include <linux/srcu.h> 26 27 #include <linux/fsnotify_backend.h> 28 #include "fsnotify.h" 29 #include "../mount.h" 30 31 /* 32 * Clear all of the marks on an inode when it is being evicted from core 33 */ 34 void __fsnotify_inode_delete(struct inode *inode) 35 { 36 fsnotify_clear_marks_by_inode(inode); 37 } 38 EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); 39 40 void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 41 { 42 fsnotify_clear_marks_by_mount(mnt); 43 } 44 45 /* 46 * Given an inode, first check if we care what happens to our children. Inotify 47 * and dnotify both tell their parents about events. If we care about any event 48 * on a child we run all of our children and set a dentry flag saying that the 49 * parent cares. Thus when an event happens on a child it can quickly tell if 50 * if there is a need to find a parent and send the event to the parent. 51 */ 52 void __fsnotify_update_child_dentry_flags(struct inode *inode) 53 { 54 struct dentry *alias; 55 int watched; 56 57 if (!S_ISDIR(inode->i_mode)) 58 return; 59 60 /* determine if the children should tell inode about their events */ 61 watched = fsnotify_inode_watches_children(inode); 62 63 spin_lock(&inode->i_lock); 64 /* run all of the dentries associated with this inode. Since this is a 65 * directory, there damn well better only be one item on this list */ 66 hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { 67 struct dentry *child; 68 69 /* run all of the children of the original inode and fix their 70 * d_flags to indicate parental interest (their parent is the 71 * original inode) */ 72 spin_lock(&alias->d_lock); 73 list_for_each_entry(child, &alias->d_subdirs, d_child) { 74 if (!child->d_inode) 75 continue; 76 77 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); 78 if (watched) 79 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 80 else 81 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 82 spin_unlock(&child->d_lock); 83 } 84 spin_unlock(&alias->d_lock); 85 } 86 spin_unlock(&inode->i_lock); 87 } 88 89 /* Notify this dentry's parent about a child's events. */ 90 int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 91 { 92 struct dentry *parent; 93 struct inode *p_inode; 94 int ret = 0; 95 96 if (!dentry) 97 dentry = path->dentry; 98 99 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) 100 return 0; 101 102 parent = dget_parent(dentry); 103 p_inode = parent->d_inode; 104 105 if (unlikely(!fsnotify_inode_watches_children(p_inode))) 106 __fsnotify_update_child_dentry_flags(p_inode); 107 else if (p_inode->i_fsnotify_mask & mask) { 108 /* we are notifying a parent so come up with the new mask which 109 * specifies these are events which came from a child. */ 110 mask |= FS_EVENT_ON_CHILD; 111 112 if (path) 113 ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, 114 dentry->d_name.name, 0); 115 else 116 ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, 117 dentry->d_name.name, 0); 118 } 119 120 dput(parent); 121 122 return ret; 123 } 124 EXPORT_SYMBOL_GPL(__fsnotify_parent); 125 126 static int send_to_group(struct inode *to_tell, 127 struct fsnotify_mark *inode_mark, 128 struct fsnotify_mark *vfsmount_mark, 129 __u32 mask, void *data, 130 int data_is, u32 cookie, 131 const unsigned char *file_name) 132 { 133 struct fsnotify_group *group = NULL; 134 __u32 inode_test_mask = 0; 135 __u32 vfsmount_test_mask = 0; 136 137 if (unlikely(!inode_mark && !vfsmount_mark)) { 138 BUG(); 139 return 0; 140 } 141 142 /* clear ignored on inode modification */ 143 if (mask & FS_MODIFY) { 144 if (inode_mark && 145 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 146 inode_mark->ignored_mask = 0; 147 if (vfsmount_mark && 148 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 149 vfsmount_mark->ignored_mask = 0; 150 } 151 152 /* does the inode mark tell us to do something? */ 153 if (inode_mark) { 154 group = inode_mark->group; 155 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD); 156 inode_test_mask &= inode_mark->mask; 157 inode_test_mask &= ~inode_mark->ignored_mask; 158 } 159 160 /* does the vfsmount_mark tell us to do something? */ 161 if (vfsmount_mark) { 162 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD); 163 group = vfsmount_mark->group; 164 vfsmount_test_mask &= vfsmount_mark->mask; 165 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask; 166 if (inode_mark) 167 vfsmount_test_mask &= ~inode_mark->ignored_mask; 168 } 169 170 pr_debug("%s: group=%p to_tell=%p mask=%x inode_mark=%p" 171 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x" 172 " data=%p data_is=%d cookie=%d\n", 173 __func__, group, to_tell, mask, inode_mark, 174 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data, 175 data_is, cookie); 176 177 if (!inode_test_mask && !vfsmount_test_mask) 178 return 0; 179 180 return group->ops->handle_event(group, to_tell, inode_mark, 181 vfsmount_mark, mask, data, data_is, 182 file_name, cookie); 183 } 184 185 /* 186 * This is the main call to fsnotify. The VFS calls into hook specific functions 187 * in linux/fsnotify.h. Those functions then in turn call here. Here will call 188 * out to all of the registered fsnotify_group. Those groups can then use the 189 * notification event in whatever means they feel necessary. 190 */ 191 int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 192 const unsigned char *file_name, u32 cookie) 193 { 194 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL; 195 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL; 196 struct fsnotify_group *inode_group, *vfsmount_group; 197 struct mount *mnt; 198 int idx, ret = 0; 199 /* global tests shouldn't care about events on child only the specific event */ 200 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); 201 202 if (data_is == FSNOTIFY_EVENT_PATH) 203 mnt = real_mount(((struct path *)data)->mnt); 204 else 205 mnt = NULL; 206 207 /* 208 * if this is a modify event we may need to clear the ignored masks 209 * otherwise return if neither the inode nor the vfsmount care about 210 * this type of event. 211 */ 212 if (!(mask & FS_MODIFY) && 213 !(test_mask & to_tell->i_fsnotify_mask) && 214 !(mnt && test_mask & mnt->mnt_fsnotify_mask)) 215 return 0; 216 217 idx = srcu_read_lock(&fsnotify_mark_srcu); 218 219 if ((mask & FS_MODIFY) || 220 (test_mask & to_tell->i_fsnotify_mask)) 221 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 222 &fsnotify_mark_srcu); 223 224 if (mnt && ((mask & FS_MODIFY) || 225 (test_mask & mnt->mnt_fsnotify_mask))) { 226 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first, 227 &fsnotify_mark_srcu); 228 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 229 &fsnotify_mark_srcu); 230 } 231 232 /* 233 * We need to merge inode & vfsmount mark lists so that inode mark 234 * ignore masks are properly reflected for mount mark notifications. 235 * That's why this traversal is so complicated... 236 */ 237 while (inode_node || vfsmount_node) { 238 inode_group = NULL; 239 inode_mark = NULL; 240 vfsmount_group = NULL; 241 vfsmount_mark = NULL; 242 243 if (inode_node) { 244 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu), 245 struct fsnotify_mark, obj_list); 246 inode_group = inode_mark->group; 247 } 248 249 if (vfsmount_node) { 250 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu), 251 struct fsnotify_mark, obj_list); 252 vfsmount_group = vfsmount_mark->group; 253 } 254 255 if (inode_group && vfsmount_group) { 256 int cmp = fsnotify_compare_groups(inode_group, 257 vfsmount_group); 258 if (cmp > 0) { 259 inode_group = NULL; 260 inode_mark = NULL; 261 } else if (cmp < 0) { 262 vfsmount_group = NULL; 263 vfsmount_mark = NULL; 264 } 265 } 266 ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask, 267 data, data_is, cookie, file_name); 268 269 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS)) 270 goto out; 271 272 if (inode_group) 273 inode_node = srcu_dereference(inode_node->next, 274 &fsnotify_mark_srcu); 275 if (vfsmount_group) 276 vfsmount_node = srcu_dereference(vfsmount_node->next, 277 &fsnotify_mark_srcu); 278 } 279 ret = 0; 280 out: 281 srcu_read_unlock(&fsnotify_mark_srcu, idx); 282 283 return ret; 284 } 285 EXPORT_SYMBOL_GPL(fsnotify); 286 287 static __init int fsnotify_init(void) 288 { 289 int ret; 290 291 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); 292 293 ret = init_srcu_struct(&fsnotify_mark_srcu); 294 if (ret) 295 panic("initializing fsnotify_mark_srcu"); 296 297 return 0; 298 } 299 core_initcall(fsnotify_init); 300