Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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/fs.h>
20#include <linux/init.h>
21#include <linux/kernel.h>
22#include <linux/module.h>
23#include <linux/mutex.h>
24#include <linux/spinlock.h>
25
26#include <linux/atomic.h>
27
28#include <linux/fsnotify_backend.h>
29#include "fsnotify.h"
30
31#include "../internal.h"
32
33/*
34 * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types
35 * any notifier is interested in hearing for this inode.
36 */
37void fsnotify_recalc_inode_mask(struct inode *inode)
38{
39 spin_lock(&inode->i_lock);
40 inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks);
41 spin_unlock(&inode->i_lock);
42
43 __fsnotify_update_child_dentry_flags(inode);
44}
45
46void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
47{
48 struct inode *inode = mark->inode;
49
50 BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
51 assert_spin_locked(&mark->lock);
52
53 spin_lock(&inode->i_lock);
54
55 hlist_del_init_rcu(&mark->obj_list);
56 mark->inode = NULL;
57
58 /*
59 * this mark is now off the inode->i_fsnotify_marks list and we
60 * hold the inode->i_lock, so this is the perfect time to update the
61 * inode->i_fsnotify_mask
62 */
63 inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks);
64 spin_unlock(&inode->i_lock);
65}
66
67/*
68 * Given a group clear all of the inode marks associated with that group.
69 */
70void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
71{
72 fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
73}
74
75/*
76 * given a group and inode, find the mark associated with that combination.
77 * if found take a reference to that mark and return it, else return NULL
78 */
79struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group,
80 struct inode *inode)
81{
82 struct fsnotify_mark *mark;
83
84 spin_lock(&inode->i_lock);
85 mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
86 spin_unlock(&inode->i_lock);
87
88 return mark;
89}
90
91/*
92 * If we are setting a mark mask on an inode mark we should pin the inode
93 * in memory.
94 */
95void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
96 __u32 mask)
97{
98 struct inode *inode;
99
100 assert_spin_locked(&mark->lock);
101
102 if (mask &&
103 mark->inode &&
104 !(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
105 mark->flags |= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
106 inode = igrab(mark->inode);
107 /*
108 * we shouldn't be able to get here if the inode wasn't
109 * already safely held in memory. But bug in case it
110 * ever is wrong.
111 */
112 BUG_ON(!inode);
113 }
114}
115
116/*
117 * Attach an initialized mark to a given inode.
118 * These marks may be used for the fsnotify backend to determine which
119 * event types should be delivered to which group and for which inodes. These
120 * marks are ordered according to priority, highest number first, and then by
121 * the group's location in memory.
122 */
123int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
124 struct fsnotify_group *group, struct inode *inode,
125 int allow_dups)
126{
127 int ret;
128
129 mark->flags |= FSNOTIFY_MARK_FLAG_INODE;
130
131 BUG_ON(!mutex_is_locked(&group->mark_mutex));
132 assert_spin_locked(&mark->lock);
133
134 spin_lock(&inode->i_lock);
135 mark->inode = inode;
136 ret = fsnotify_add_mark_list(&inode->i_fsnotify_marks, mark,
137 allow_dups);
138 inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks);
139 spin_unlock(&inode->i_lock);
140
141 return ret;
142}
143
144/**
145 * fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
146 * @sb: superblock being unmounted.
147 *
148 * Called during unmount with no locks held, so needs to be safe against
149 * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block.
150 */
151void fsnotify_unmount_inodes(struct super_block *sb)
152{
153 struct inode *inode, *next_i, *need_iput = NULL;
154
155 spin_lock(&sb->s_inode_list_lock);
156 list_for_each_entry_safe(inode, next_i, &sb->s_inodes, i_sb_list) {
157 struct inode *need_iput_tmp;
158
159 /*
160 * We cannot __iget() an inode in state I_FREEING,
161 * I_WILL_FREE, or I_NEW which is fine because by that point
162 * the inode cannot have any associated watches.
163 */
164 spin_lock(&inode->i_lock);
165 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
166 spin_unlock(&inode->i_lock);
167 continue;
168 }
169
170 /*
171 * If i_count is zero, the inode cannot have any watches and
172 * doing an __iget/iput with MS_ACTIVE clear would actually
173 * evict all inodes with zero i_count from icache which is
174 * unnecessarily violent and may in fact be illegal to do.
175 */
176 if (!atomic_read(&inode->i_count)) {
177 spin_unlock(&inode->i_lock);
178 continue;
179 }
180
181 need_iput_tmp = need_iput;
182 need_iput = NULL;
183
184 /* In case fsnotify_inode_delete() drops a reference. */
185 if (inode != need_iput_tmp)
186 __iget(inode);
187 else
188 need_iput_tmp = NULL;
189 spin_unlock(&inode->i_lock);
190
191 /* In case the dropping of a reference would nuke next_i. */
192 while (&next_i->i_sb_list != &sb->s_inodes) {
193 spin_lock(&next_i->i_lock);
194 if (!(next_i->i_state & (I_FREEING | I_WILL_FREE)) &&
195 atomic_read(&next_i->i_count)) {
196 __iget(next_i);
197 need_iput = next_i;
198 spin_unlock(&next_i->i_lock);
199 break;
200 }
201 spin_unlock(&next_i->i_lock);
202 next_i = list_next_entry(next_i, i_sb_list);
203 }
204
205 /*
206 * We can safely drop s_inode_list_lock here because either
207 * we actually hold references on both inode and next_i or
208 * end of list. Also no new inodes will be added since the
209 * umount has begun.
210 */
211 spin_unlock(&sb->s_inode_list_lock);
212
213 if (need_iput_tmp)
214 iput(need_iput_tmp);
215
216 /* for each watch, send FS_UNMOUNT and then remove it */
217 fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
218
219 fsnotify_inode_delete(inode);
220
221 iput(inode);
222
223 spin_lock(&sb->s_inode_list_lock);
224 }
225 spin_unlock(&sb->s_inode_list_lock);
226}