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c82ee6d3 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
90586523 EP |
2 | /* |
3 | * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> | |
90586523 EP |
4 | */ |
5 | ||
6 | #include <linux/list.h> | |
7 | #include <linux/mutex.h> | |
8 | #include <linux/slab.h> | |
9 | #include <linux/srcu.h> | |
10 | #include <linux/rculist.h> | |
11 | #include <linux/wait.h> | |
d46eb14b | 12 | #include <linux/memcontrol.h> |
90586523 EP |
13 | |
14 | #include <linux/fsnotify_backend.h> | |
15 | #include "fsnotify.h" | |
16 | ||
60063497 | 17 | #include <linux/atomic.h> |
90586523 | 18 | |
90586523 EP |
19 | /* |
20 | * Final freeing of a group | |
21 | */ | |
cafbaae8 | 22 | static void fsnotify_final_destroy_group(struct fsnotify_group *group) |
90586523 EP |
23 | { |
24 | if (group->ops->free_group_priv) | |
25 | group->ops->free_group_priv(group); | |
26 | ||
d46eb14b | 27 | mem_cgroup_put(group->memcg); |
191e1656 | 28 | mutex_destroy(&group->mark_mutex); |
d46eb14b | 29 | |
90586523 EP |
30 | kfree(group); |
31 | } | |
32 | ||
12703dbf JK |
33 | /* |
34 | * Stop queueing new events for this group. Once this function returns | |
35 | * fsnotify_add_event() will not add any new events to the group's queue. | |
36 | */ | |
37 | void fsnotify_group_stop_queueing(struct fsnotify_group *group) | |
38 | { | |
c21dbe20 | 39 | spin_lock(&group->notification_lock); |
12703dbf | 40 | group->shutdown = true; |
c21dbe20 | 41 | spin_unlock(&group->notification_lock); |
12703dbf JK |
42 | } |
43 | ||
3be25f49 | 44 | /* |
23e964c2 LS |
45 | * Trying to get rid of a group. Remove all marks, flush all events and release |
46 | * the group reference. | |
47 | * Note that another thread calling fsnotify_clear_marks_by_group() may still | |
48 | * hold a ref to the group. | |
3be25f49 | 49 | */ |
d8153d4d | 50 | void fsnotify_destroy_group(struct fsnotify_group *group) |
3be25f49 | 51 | { |
12703dbf JK |
52 | /* |
53 | * Stop queueing new events. The code below is careful enough to not | |
54 | * require this but fanotify needs to stop queuing events even before | |
55 | * fsnotify_destroy_group() is called and this makes the other callers | |
56 | * of fsnotify_destroy_group() to see the same behavior. | |
57 | */ | |
58 | fsnotify_group_stop_queueing(group); | |
59 | ||
f09b04a0 | 60 | /* Clear all marks for this group and queue them for destruction */ |
ad69cd99 | 61 | fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_ANY); |
2e37c6ca JK |
62 | |
63 | /* | |
64 | * Some marks can still be pinned when waiting for response from | |
65 | * userspace. Wait for those now. fsnotify_prepare_user_wait() will | |
66 | * not succeed now so this wait is race-free. | |
67 | */ | |
68 | wait_event(group->notification_waitq, !atomic_read(&group->user_waits)); | |
3be25f49 | 69 | |
35e48176 | 70 | /* |
f09b04a0 JK |
71 | * Wait until all marks get really destroyed. We could actually destroy |
72 | * them ourselves instead of waiting for worker to do it, however that | |
73 | * would be racy as worker can already be processing some marks before | |
74 | * we even entered fsnotify_destroy_group(). | |
35e48176 | 75 | */ |
f09b04a0 | 76 | fsnotify_wait_marks_destroyed(); |
75c1be48 | 77 | |
35e48176 JK |
78 | /* |
79 | * Since we have waited for fsnotify_mark_srcu in | |
80 | * fsnotify_mark_destroy_list() there can be no outstanding event | |
81 | * notification against this group. So clearing the notification queue | |
82 | * of all events is reliable now. | |
83 | */ | |
23e964c2 LS |
84 | fsnotify_flush_notify(group); |
85 | ||
ff57cd58 JK |
86 | /* |
87 | * Destroy overflow event (we cannot use fsnotify_destroy_event() as | |
88 | * that deliberately ignores overflow events. | |
89 | */ | |
90 | if (group->overflow_event) | |
330ae77d | 91 | group->ops->free_event(group, group->overflow_event); |
ff57cd58 | 92 | |
23e964c2 | 93 | fsnotify_put_group(group); |
3be25f49 EP |
94 | } |
95 | ||
98612952 LS |
96 | /* |
97 | * Get reference to a group. | |
98 | */ | |
99 | void fsnotify_get_group(struct fsnotify_group *group) | |
100 | { | |
7761daa6 | 101 | refcount_inc(&group->refcnt); |
98612952 LS |
102 | } |
103 | ||
90586523 EP |
104 | /* |
105 | * Drop a reference to a group. Free it if it's through. | |
106 | */ | |
107 | void fsnotify_put_group(struct fsnotify_group *group) | |
108 | { | |
7761daa6 | 109 | if (refcount_dec_and_test(&group->refcnt)) |
23e964c2 | 110 | fsnotify_final_destroy_group(group); |
90586523 | 111 | } |
b72679ee | 112 | EXPORT_SYMBOL_GPL(fsnotify_put_group); |
90586523 | 113 | |
ac7b79fd | 114 | static struct fsnotify_group *__fsnotify_alloc_group( |
867a448d AG |
115 | const struct fsnotify_ops *ops, |
116 | int flags, gfp_t gfp) | |
90586523 | 117 | { |
43b245a7 | 118 | static struct lock_class_key nofs_marks_lock; |
74be0cc8 | 119 | struct fsnotify_group *group; |
90586523 | 120 | |
ac7b79fd | 121 | group = kzalloc(sizeof(struct fsnotify_group), gfp); |
90586523 EP |
122 | if (!group) |
123 | return ERR_PTR(-ENOMEM); | |
124 | ||
36fddeba | 125 | /* set to 0 when there a no external references to this group */ |
7761daa6 | 126 | refcount_set(&group->refcnt, 1); |
abc77577 | 127 | atomic_set(&group->user_waits, 0); |
36fddeba | 128 | |
c21dbe20 | 129 | spin_lock_init(&group->notification_lock); |
a2d8bc6c EP |
130 | INIT_LIST_HEAD(&group->notification_list); |
131 | init_waitqueue_head(&group->notification_waitq); | |
a2d8bc6c EP |
132 | group->max_events = UINT_MAX; |
133 | ||
986ab098 | 134 | mutex_init(&group->mark_mutex); |
e61ce867 | 135 | INIT_LIST_HEAD(&group->marks_list); |
3be25f49 | 136 | |
90586523 | 137 | group->ops = ops; |
867a448d | 138 | group->flags = flags; |
43b245a7 AG |
139 | /* |
140 | * For most backends, eviction of inode with a mark is not expected, | |
141 | * because marks hold a refcount on the inode against eviction. | |
142 | * | |
143 | * Use a different lockdep class for groups that support evictable | |
144 | * inode marks, because with evictable marks, mark_mutex is NOT | |
145 | * fs-reclaim safe - the mutex is taken when evicting inodes. | |
146 | */ | |
147 | if (flags & FSNOTIFY_GROUP_NOFS) | |
148 | lockdep_set_class(&group->mark_mutex, &nofs_marks_lock); | |
90586523 | 149 | |
90586523 EP |
150 | return group; |
151 | } | |
ac7b79fd SB |
152 | |
153 | /* | |
154 | * Create a new fsnotify_group and hold a reference for the group returned. | |
155 | */ | |
867a448d AG |
156 | struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops, |
157 | int flags) | |
ac7b79fd | 158 | { |
867a448d AG |
159 | gfp_t gfp = (flags & FSNOTIFY_GROUP_USER) ? GFP_KERNEL_ACCOUNT : |
160 | GFP_KERNEL; | |
0a6b6bd5 | 161 | |
867a448d | 162 | return __fsnotify_alloc_group(ops, flags, gfp); |
ac7b79fd | 163 | } |
867a448d | 164 | EXPORT_SYMBOL_GPL(fsnotify_alloc_group); |
ac7b79fd | 165 | |
0a6b6bd5 EP |
166 | int fsnotify_fasync(int fd, struct file *file, int on) |
167 | { | |
168 | struct fsnotify_group *group = file->private_data; | |
169 | ||
170 | return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO; | |
171 | } |