2 * fs/inotify_user.c - inotify support for userspace
5 * John McCutchan <ttb@tentacle.dhs.org>
6 * Robert Love <rml@novell.com>
8 * Copyright (C) 2005 John McCutchan
9 * Copyright 2006 Hewlett-Packard Development Company, L.P.
11 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
12 * inotify was largely rewriten to make use of the fsnotify infrastructure
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License as published by the
16 * Free Software Foundation; either version 2, or (at your option) any
19 * This program is distributed in the hope that it will be useful, but
20 * WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 * General Public License for more details.
25 #include <linux/dcache.h> /* d_unlinked */
26 #include <linux/fs.h> /* struct inode */
27 #include <linux/fsnotify_backend.h>
28 #include <linux/inotify.h>
29 #include <linux/path.h> /* struct path */
30 #include <linux/slab.h> /* kmem_* */
31 #include <linux/types.h>
32 #include <linux/sched.h>
33 #include <linux/sched/user.h>
34 #include <linux/sched/mm.h>
39 * Check if 2 events contain the same information.
41 static bool event_compare(struct fsnotify_event *old_fsn,
42 struct fsnotify_event *new_fsn)
44 struct inotify_event_info *old, *new;
46 if (old_fsn->mask & FS_IN_IGNORED)
48 old = INOTIFY_E(old_fsn);
49 new = INOTIFY_E(new_fsn);
50 if ((old_fsn->mask == new_fsn->mask) &&
51 (old_fsn->inode == new_fsn->inode) &&
52 (old->name_len == new->name_len) &&
53 (!old->name_len || !strcmp(old->name, new->name)))
58 static int inotify_merge(struct list_head *list,
59 struct fsnotify_event *event)
61 struct fsnotify_event *last_event;
63 last_event = list_entry(list->prev, struct fsnotify_event, list);
64 return event_compare(last_event, event);
67 int inotify_handle_event(struct fsnotify_group *group,
69 u32 mask, const void *data, int data_type,
70 const unsigned char *file_name, u32 cookie,
71 struct fsnotify_iter_info *iter_info)
73 struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
74 struct inotify_inode_mark *i_mark;
75 struct inotify_event_info *event;
76 struct fsnotify_event *fsn_event;
79 int alloc_len = sizeof(struct inotify_event_info);
81 if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info)))
84 if ((inode_mark->mask & FS_EXCL_UNLINK) &&
85 (data_type == FSNOTIFY_EVENT_PATH)) {
86 const struct path *path = data;
88 if (d_unlinked(path->dentry))
92 len = strlen(file_name);
96 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
99 i_mark = container_of(inode_mark, struct inotify_inode_mark,
103 * Whoever is interested in the event, pays for the allocation. Do not
104 * trigger OOM killer in the target monitoring memcg as it may have
105 * security repercussion.
107 memalloc_use_memcg(group->memcg);
108 event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
109 memalloc_unuse_memcg();
111 if (unlikely(!event)) {
113 * Treat lost event due to ENOMEM the same way as queue
114 * overflow to let userspace know event was lost.
116 fsnotify_queue_overflow(group);
120 fsn_event = &event->fse;
121 fsnotify_init_event(fsn_event, inode, mask);
122 event->wd = i_mark->wd;
123 event->sync_cookie = cookie;
124 event->name_len = len;
126 strcpy(event->name, file_name);
128 ret = fsnotify_add_event(group, fsn_event, inotify_merge);
130 /* Our event wasn't used in the end. Free it. */
131 fsnotify_destroy_event(group, fsn_event);
134 if (inode_mark->mask & IN_ONESHOT)
135 fsnotify_destroy_mark(inode_mark, group);
140 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
142 inotify_ignored_and_remove_idr(fsn_mark, group);
146 * This is NEVER supposed to be called. Inotify marks should either have been
147 * removed from the idr when the watch was removed or in the
148 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
149 * torn down. This is only called if the idr is about to be freed but there
150 * are still marks in it.
152 static int idr_callback(int id, void *p, void *data)
154 struct fsnotify_mark *fsn_mark;
155 struct inotify_inode_mark *i_mark;
156 static bool warned = false;
163 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
165 WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
166 "idr. Probably leaking memory\n", id, p, data);
169 * I'm taking the liberty of assuming that the mark in question is a
170 * valid address and I'm dereferencing it. This might help to figure
171 * out why we got here and the panic is no worse than the original
172 * BUG() that was here.
175 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
176 fsn_mark->group, i_mark->wd);
180 static void inotify_free_group_priv(struct fsnotify_group *group)
182 /* ideally the idr is empty and we won't hit the BUG in the callback */
183 idr_for_each(&group->inotify_data.idr, idr_callback, group);
184 idr_destroy(&group->inotify_data.idr);
185 if (group->inotify_data.ucounts)
186 dec_inotify_instances(group->inotify_data.ucounts);
189 static void inotify_free_event(struct fsnotify_event *fsn_event)
191 kfree(INOTIFY_E(fsn_event));
194 /* ding dong the mark is dead */
195 static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
197 struct inotify_inode_mark *i_mark;
199 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
201 kmem_cache_free(inotify_inode_mark_cachep, i_mark);
204 const struct fsnotify_ops inotify_fsnotify_ops = {
205 .handle_event = inotify_handle_event,
206 .free_group_priv = inotify_free_group_priv,
207 .free_event = inotify_free_event,
208 .freeing_mark = inotify_freeing_mark,
209 .free_mark = inotify_free_mark,