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90586523 EP |
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/list.h> | |
20 | #include <linux/mutex.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/srcu.h> | |
23 | #include <linux/rculist.h> | |
24 | #include <linux/wait.h> | |
25 | ||
26 | #include <linux/fsnotify_backend.h> | |
27 | #include "fsnotify.h" | |
28 | ||
29 | #include <asm/atomic.h> | |
30 | ||
31 | /* protects writes to fsnotify_groups and fsnotify_mask */ | |
32 | static DEFINE_MUTEX(fsnotify_grp_mutex); | |
7131485a | 33 | /* all groups registered to receive inode filesystem notifications */ |
19c2a0e1 | 34 | LIST_HEAD(fsnotify_inode_groups); |
7131485a EP |
35 | /* all groups registered to receive mount point filesystem notifications */ |
36 | LIST_HEAD(fsnotify_vfsmount_groups); | |
90586523 | 37 | |
3be25f49 EP |
38 | /* |
39 | * Update the group->mask by running all of the marks associated with this | |
03930979 | 40 | * group and finding the bitwise | of all of the mark->mask. |
3be25f49 EP |
41 | */ |
42 | void fsnotify_recalc_group_mask(struct fsnotify_group *group) | |
43 | { | |
44 | __u32 mask = 0; | |
841bdc10 | 45 | struct fsnotify_mark *mark; |
3be25f49 EP |
46 | |
47 | spin_lock(&group->mark_lock); | |
841bdc10 EP |
48 | list_for_each_entry(mark, &group->marks_list, g_list) |
49 | mask |= mark->mask; | |
3be25f49 | 50 | group->mask = mask; |
03930979 | 51 | spin_unlock(&group->mark_lock); |
3be25f49 EP |
52 | } |
53 | ||
7131485a EP |
54 | void fsnotify_add_vfsmount_group(struct fsnotify_group *group) |
55 | { | |
cb2d429f | 56 | struct fsnotify_group *group_iter; |
cb2d429f | 57 | |
7131485a EP |
58 | mutex_lock(&fsnotify_grp_mutex); |
59 | ||
cb2d429f EP |
60 | if (!group->on_vfsmount_group_list) { |
61 | list_for_each_entry(group_iter, &fsnotify_vfsmount_groups, | |
62 | vfsmount_group_list) { | |
63 | /* insert in front of this one? */ | |
08ae8938 | 64 | if (group < group_iter) { |
cb2d429f EP |
65 | /* list_add_tail() insert in front of group_iter */ |
66 | list_add_tail_rcu(&group->inode_group_list, | |
67 | &group_iter->inode_group_list); | |
68 | goto out; | |
69 | } | |
70 | } | |
71 | ||
72 | /* apparently we need to be the last entry */ | |
7131485a | 73 | list_add_tail_rcu(&group->vfsmount_group_list, &fsnotify_vfsmount_groups); |
cb2d429f EP |
74 | } |
75 | out: | |
7131485a EP |
76 | group->on_vfsmount_group_list = 1; |
77 | ||
78 | mutex_unlock(&fsnotify_grp_mutex); | |
79 | } | |
80 | ||
4ca76352 | 81 | void fsnotify_add_inode_group(struct fsnotify_group *group) |
19c2a0e1 | 82 | { |
cb2d429f | 83 | struct fsnotify_group *group_iter; |
cb2d429f | 84 | |
4ca76352 | 85 | mutex_lock(&fsnotify_grp_mutex); |
19c2a0e1 | 86 | |
08ae8938 | 87 | /* add to global group list */ |
cb2d429f EP |
88 | if (!group->on_inode_group_list) { |
89 | list_for_each_entry(group_iter, &fsnotify_inode_groups, | |
90 | inode_group_list) { | |
08ae8938 | 91 | if (group < group_iter) { |
cb2d429f EP |
92 | /* list_add_tail() insert in front of group_iter */ |
93 | list_add_tail_rcu(&group->inode_group_list, | |
94 | &group_iter->inode_group_list); | |
95 | goto out; | |
96 | } | |
97 | } | |
98 | ||
99 | /* apparently we need to be the last entry */ | |
4ca76352 | 100 | list_add_tail_rcu(&group->inode_group_list, &fsnotify_inode_groups); |
cb2d429f EP |
101 | } |
102 | out: | |
19c2a0e1 | 103 | group->on_inode_group_list = 1; |
4ca76352 EP |
104 | |
105 | mutex_unlock(&fsnotify_grp_mutex); | |
19c2a0e1 EP |
106 | } |
107 | ||
90586523 EP |
108 | /* |
109 | * Final freeing of a group | |
110 | */ | |
3be25f49 | 111 | void fsnotify_final_destroy_group(struct fsnotify_group *group) |
90586523 | 112 | { |
a2d8bc6c EP |
113 | /* clear the notification queue of all events */ |
114 | fsnotify_flush_notify(group); | |
115 | ||
90586523 EP |
116 | if (group->ops->free_group_priv) |
117 | group->ops->free_group_priv(group); | |
118 | ||
119 | kfree(group); | |
120 | } | |
121 | ||
3be25f49 EP |
122 | /* |
123 | * Trying to get rid of a group. We need to first get rid of any outstanding | |
124 | * allocations and then free the group. Remember that fsnotify_clear_marks_by_group | |
125 | * could miss marks that are being freed by inode and those marks could still | |
126 | * hold a reference to this group (via group->num_marks) If we get into that | |
127 | * situtation, the fsnotify_final_destroy_group will get called when that final | |
128 | * mark is freed. | |
129 | */ | |
130 | static void fsnotify_destroy_group(struct fsnotify_group *group) | |
131 | { | |
e61ce867 | 132 | /* clear all inode marks for this group */ |
3be25f49 EP |
133 | fsnotify_clear_marks_by_group(group); |
134 | ||
75c1be48 EP |
135 | synchronize_srcu(&fsnotify_mark_srcu); |
136 | ||
3be25f49 EP |
137 | /* past the point of no return, matches the initial value of 1 */ |
138 | if (atomic_dec_and_test(&group->num_marks)) | |
139 | fsnotify_final_destroy_group(group); | |
140 | } | |
141 | ||
90586523 EP |
142 | /* |
143 | * Remove this group from the global list of groups that will get events | |
144 | * this can be done even if there are still references and things still using | |
145 | * this group. This just stops the group from getting new events. | |
146 | */ | |
147 | static void __fsnotify_evict_group(struct fsnotify_group *group) | |
148 | { | |
149 | BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex)); | |
150 | ||
19c2a0e1 EP |
151 | if (group->on_inode_group_list) |
152 | list_del_rcu(&group->inode_group_list); | |
153 | group->on_inode_group_list = 0; | |
7131485a EP |
154 | if (group->on_vfsmount_group_list) |
155 | list_del_rcu(&group->vfsmount_group_list); | |
156 | group->on_vfsmount_group_list = 0; | |
90586523 EP |
157 | } |
158 | ||
159 | /* | |
160 | * Called when a group is no longer interested in getting events. This can be | |
161 | * used if a group is misbehaving or if for some reason a group should no longer | |
162 | * get any filesystem events. | |
163 | */ | |
164 | void fsnotify_evict_group(struct fsnotify_group *group) | |
165 | { | |
166 | mutex_lock(&fsnotify_grp_mutex); | |
167 | __fsnotify_evict_group(group); | |
168 | mutex_unlock(&fsnotify_grp_mutex); | |
169 | } | |
170 | ||
171 | /* | |
172 | * Drop a reference to a group. Free it if it's through. | |
173 | */ | |
174 | void fsnotify_put_group(struct fsnotify_group *group) | |
175 | { | |
176 | if (!atomic_dec_and_mutex_lock(&group->refcnt, &fsnotify_grp_mutex)) | |
177 | return; | |
178 | ||
179 | /* | |
180 | * OK, now we know that there's no other users *and* we hold mutex, | |
181 | * so no new references will appear | |
182 | */ | |
183 | __fsnotify_evict_group(group); | |
184 | ||
90586523 | 185 | mutex_unlock(&fsnotify_grp_mutex); |
90586523 | 186 | |
90586523 EP |
187 | fsnotify_destroy_group(group); |
188 | } | |
189 | ||
90586523 | 190 | /* |
ffab8340 | 191 | * Create a new fsnotify_group and hold a reference for the group returned. |
90586523 | 192 | */ |
0d2e2a1d | 193 | struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) |
90586523 | 194 | { |
74be0cc8 | 195 | struct fsnotify_group *group; |
90586523 | 196 | |
f0553af0 | 197 | group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); |
90586523 EP |
198 | if (!group) |
199 | return ERR_PTR(-ENOMEM); | |
200 | ||
36fddeba | 201 | /* set to 0 when there a no external references to this group */ |
90586523 | 202 | atomic_set(&group->refcnt, 1); |
36fddeba EP |
203 | /* |
204 | * hits 0 when there are no external references AND no marks for | |
205 | * this group | |
206 | */ | |
207 | atomic_set(&group->num_marks, 1); | |
208 | ||
a2d8bc6c EP |
209 | mutex_init(&group->notification_mutex); |
210 | INIT_LIST_HEAD(&group->notification_list); | |
211 | init_waitqueue_head(&group->notification_waitq); | |
a2d8bc6c EP |
212 | group->max_events = UINT_MAX; |
213 | ||
4ca76352 | 214 | INIT_LIST_HEAD(&group->inode_group_list); |
7131485a | 215 | INIT_LIST_HEAD(&group->vfsmount_group_list); |
4ca76352 | 216 | |
3be25f49 | 217 | spin_lock_init(&group->mark_lock); |
e61ce867 | 218 | INIT_LIST_HEAD(&group->marks_list); |
3be25f49 | 219 | |
90586523 EP |
220 | group->ops = ops; |
221 | ||
90586523 EP |
222 | return group; |
223 | } |