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 30 /* 31 * Clear all of the marks on an inode when it is being evicted from core 32 */ 33 void __fsnotify_inode_delete(struct inode *inode) 34 { 35 fsnotify_clear_marks_by_inode(inode); 36 } 37 EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); 38 39 void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 40 { 41 fsnotify_clear_marks_by_mount(mnt); 42 } 43 44 /* 45 * Given an inode, first check if we care what happens to our children. Inotify 46 * and dnotify both tell their parents about events. If we care about any event 47 * on a child we run all of our children and set a dentry flag saying that the 48 * parent cares. Thus when an event happens on a child it can quickly tell if 49 * if there is a need to find a parent and send the event to the parent. 50 */ 51 void __fsnotify_update_child_dentry_flags(struct inode *inode) 52 { 53 struct dentry *alias; 54 int watched; 55 56 if (!S_ISDIR(inode->i_mode)) 57 return; 58 59 /* determine if the children should tell inode about their events */ 60 watched = fsnotify_inode_watches_children(inode); 61 62 spin_lock(&dcache_lock); 63 /* run all of the dentries associated with this inode. Since this is a 64 * directory, there damn well better only be one item on this list */ 65 list_for_each_entry(alias, &inode->i_dentry, d_alias) { 66 struct dentry *child; 67 68 /* run all of the children of the original inode and fix their 69 * d_flags to indicate parental interest (their parent is the 70 * original inode) */ 71 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { 72 if (!child->d_inode) 73 continue; 74 75 spin_lock(&child->d_lock); 76 if (watched) 77 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 78 else 79 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 80 spin_unlock(&child->d_lock); 81 } 82 } 83 spin_unlock(&dcache_lock); 84 } 85 86 /* Notify this dentry's parent about a child's events. */ 87 int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 88 { 89 struct dentry *parent; 90 struct inode *p_inode; 91 int ret = 0; 92 93 if (!dentry) 94 dentry = path->dentry; 95 96 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) 97 return 0; 98 99 parent = dget_parent(dentry); 100 p_inode = parent->d_inode; 101 102 if (unlikely(!fsnotify_inode_watches_children(p_inode))) 103 __fsnotify_update_child_dentry_flags(p_inode); 104 else if (p_inode->i_fsnotify_mask & mask) { 105 /* we are notifying a parent so come up with the new mask which 106 * specifies these are events which came from a child. */ 107 mask |= FS_EVENT_ON_CHILD; 108 109 if (path) 110 ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, 111 dentry->d_name.name, 0); 112 else 113 ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, 114 dentry->d_name.name, 0); 115 } 116 117 dput(parent); 118 119 return ret; 120 } 121 EXPORT_SYMBOL_GPL(__fsnotify_parent); 122 123 static int send_to_group(struct inode *to_tell, struct vfsmount *mnt, 124 struct fsnotify_mark *inode_mark, 125 struct fsnotify_mark *vfsmount_mark, 126 __u32 mask, void *data, 127 int data_is, u32 cookie, 128 const unsigned char *file_name, 129 struct fsnotify_event **event) 130 { 131 struct fsnotify_group *group = NULL; 132 __u32 inode_test_mask = 0; 133 __u32 vfsmount_test_mask = 0; 134 135 if (unlikely(!inode_mark && !vfsmount_mark)) { 136 BUG(); 137 return 0; 138 } 139 140 /* clear ignored on inode modification */ 141 if (mask & FS_MODIFY) { 142 if (inode_mark && 143 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 144 inode_mark->ignored_mask = 0; 145 if (vfsmount_mark && 146 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 147 vfsmount_mark->ignored_mask = 0; 148 } 149 150 /* does the inode mark tell us to do something? */ 151 if (inode_mark) { 152 group = inode_mark->group; 153 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD); 154 inode_test_mask &= inode_mark->mask; 155 inode_test_mask &= ~inode_mark->ignored_mask; 156 } 157 158 /* does the vfsmount_mark tell us to do something? */ 159 if (vfsmount_mark) { 160 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD); 161 group = vfsmount_mark->group; 162 vfsmount_test_mask &= vfsmount_mark->mask; 163 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask; 164 if (inode_mark) 165 vfsmount_test_mask &= ~inode_mark->ignored_mask; 166 } 167 168 pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p" 169 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x" 170 " data=%p data_is=%d cookie=%d event=%p\n", 171 __func__, group, to_tell, mnt, mask, inode_mark, 172 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data, 173 data_is, cookie, *event); 174 175 if (!inode_test_mask && !vfsmount_test_mask) 176 return 0; 177 178 if (group->ops->should_send_event(group, to_tell, inode_mark, 179 vfsmount_mark, mask, data, 180 data_is) == false) 181 return 0; 182 183 if (!*event) { 184 *event = fsnotify_create_event(to_tell, mask, data, 185 data_is, file_name, 186 cookie, GFP_KERNEL); 187 if (!*event) 188 return -ENOMEM; 189 } 190 return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event); 191 } 192 193 /* 194 * This is the main call to fsnotify. The VFS calls into hook specific functions 195 * in linux/fsnotify.h. Those functions then in turn call here. Here will call 196 * out to all of the registered fsnotify_group. Those groups can then use the 197 * notification event in whatever means they feel necessary. 198 */ 199 int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 200 const unsigned char *file_name, u32 cookie) 201 { 202 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL; 203 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL; 204 struct fsnotify_group *inode_group, *vfsmount_group; 205 struct fsnotify_event *event = NULL; 206 struct vfsmount *mnt; 207 int idx, ret = 0; 208 /* global tests shouldn't care about events on child only the specific event */ 209 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); 210 211 if (data_is == FSNOTIFY_EVENT_PATH) 212 mnt = ((struct path *)data)->mnt; 213 else 214 mnt = NULL; 215 216 /* 217 * if this is a modify event we may need to clear the ignored masks 218 * otherwise return if neither the inode nor the vfsmount care about 219 * this type of event. 220 */ 221 if (!(mask & FS_MODIFY) && 222 !(test_mask & to_tell->i_fsnotify_mask) && 223 !(mnt && test_mask & mnt->mnt_fsnotify_mask)) 224 return 0; 225 226 idx = srcu_read_lock(&fsnotify_mark_srcu); 227 228 if ((mask & FS_MODIFY) || 229 (test_mask & to_tell->i_fsnotify_mask)) 230 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 231 &fsnotify_mark_srcu); 232 233 if (mnt && ((mask & FS_MODIFY) || 234 (test_mask & mnt->mnt_fsnotify_mask))) { 235 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first, 236 &fsnotify_mark_srcu); 237 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 238 &fsnotify_mark_srcu); 239 } 240 241 while (inode_node || vfsmount_node) { 242 inode_group = vfsmount_group = NULL; 243 244 if (inode_node) { 245 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu), 246 struct fsnotify_mark, i.i_list); 247 inode_group = inode_mark->group; 248 } 249 250 if (vfsmount_node) { 251 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu), 252 struct fsnotify_mark, m.m_list); 253 vfsmount_group = vfsmount_mark->group; 254 } 255 256 if (inode_group > vfsmount_group) { 257 /* handle inode */ 258 ret = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data, 259 data_is, cookie, file_name, &event); 260 /* we didn't use the vfsmount_mark */ 261 vfsmount_group = NULL; 262 } else if (vfsmount_group > inode_group) { 263 ret = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data, 264 data_is, cookie, file_name, &event); 265 inode_group = NULL; 266 } else { 267 ret = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark, 268 mask, data, data_is, cookie, file_name, 269 &event); 270 } 271 272 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS)) 273 goto out; 274 275 if (inode_group) 276 inode_node = srcu_dereference(inode_node->next, 277 &fsnotify_mark_srcu); 278 if (vfsmount_group) 279 vfsmount_node = srcu_dereference(vfsmount_node->next, 280 &fsnotify_mark_srcu); 281 } 282 ret = 0; 283 out: 284 srcu_read_unlock(&fsnotify_mark_srcu, idx); 285 /* 286 * fsnotify_create_event() took a reference so the event can't be cleaned 287 * up while we are still trying to add it to lists, drop that one. 288 */ 289 if (event) 290 fsnotify_put_event(event); 291 292 return ret; 293 } 294 EXPORT_SYMBOL_GPL(fsnotify); 295 296 static __init int fsnotify_init(void) 297 { 298 int ret; 299 300 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); 301 302 ret = init_srcu_struct(&fsnotify_mark_srcu); 303 if (ret) 304 panic("initializing fsnotify_mark_srcu"); 305 306 return 0; 307 } 308 core_initcall(fsnotify_init); 309