Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Volume handling.
3 *
4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/fs.h>
9#include <linux/slab.h>
10#include <linux/namei.h>
11#include "internal.h"
12#include <trace/events/fscache.h>
13
14/*
15 * Allocate and set up a volume representation. We make sure all the fanout
16 * directories are created and pinned.
17 */
18void cachefiles_acquire_volume(struct fscache_volume *vcookie)
19{
20 struct cachefiles_volume *volume;
21 struct cachefiles_cache *cache = vcookie->cache->cache_priv;
22 const struct cred *saved_cred;
23 struct dentry *vdentry, *fan;
24 size_t len;
25 char *name;
26 bool is_new = false;
27 int ret, n_accesses, i;
28
29 _enter("");
30
31 volume = kzalloc(sizeof(struct cachefiles_volume), GFP_KERNEL);
32 if (!volume)
33 return;
34 volume->vcookie = vcookie;
35 volume->cache = cache;
36 INIT_LIST_HEAD(&volume->cache_link);
37
38 cachefiles_begin_secure(cache, &saved_cred);
39
40 len = vcookie->key[0];
41 name = kmalloc(len + 3, GFP_NOFS);
42 if (!name)
43 goto error_vol;
44 name[0] = 'I';
45 memcpy(name + 1, vcookie->key + 1, len);
46 name[len + 1] = 0;
47
48retry:
49 vdentry = cachefiles_get_directory(cache, cache->store, name, &is_new);
50 if (IS_ERR(vdentry))
51 goto error_name;
52 volume->dentry = vdentry;
53
54 if (is_new) {
55 if (!cachefiles_set_volume_xattr(volume))
56 goto error_dir;
57 } else {
58 ret = cachefiles_check_volume_xattr(volume);
59 if (ret < 0) {
60 if (ret != -ESTALE)
61 goto error_dir;
62 vdentry = start_removing_dentry(cache->store, vdentry);
63 if (!IS_ERR(vdentry))
64 cachefiles_bury_object(cache, NULL, cache->store,
65 vdentry,
66 FSCACHE_VOLUME_IS_WEIRD);
67 cachefiles_put_directory(volume->dentry);
68 cond_resched();
69 goto retry;
70 }
71 }
72
73 for (i = 0; i < 256; i++) {
74 sprintf(name, "@%02x", i);
75 fan = cachefiles_get_directory(cache, vdentry, name, NULL);
76 if (IS_ERR(fan))
77 goto error_fan;
78 volume->fanout[i] = fan;
79 }
80
81 cachefiles_end_secure(cache, saved_cred);
82
83 vcookie->cache_priv = volume;
84 n_accesses = atomic_inc_return(&vcookie->n_accesses); /* Stop wakeups on dec-to-0 */
85 trace_fscache_access_volume(vcookie->debug_id, 0,
86 refcount_read(&vcookie->ref),
87 n_accesses, fscache_access_cache_pin);
88
89 spin_lock(&cache->object_list_lock);
90 list_add(&volume->cache_link, &volume->cache->volumes);
91 spin_unlock(&cache->object_list_lock);
92
93 kfree(name);
94 return;
95
96error_fan:
97 for (i = 0; i < 256; i++)
98 cachefiles_put_directory(volume->fanout[i]);
99error_dir:
100 cachefiles_put_directory(volume->dentry);
101error_name:
102 kfree(name);
103error_vol:
104 kfree(volume);
105 cachefiles_end_secure(cache, saved_cred);
106}
107
108/*
109 * Release a volume representation.
110 */
111static void __cachefiles_free_volume(struct cachefiles_volume *volume)
112{
113 int i;
114
115 _enter("");
116
117 volume->vcookie->cache_priv = NULL;
118
119 for (i = 0; i < 256; i++)
120 cachefiles_put_directory(volume->fanout[i]);
121 cachefiles_put_directory(volume->dentry);
122 kfree(volume);
123}
124
125void cachefiles_free_volume(struct fscache_volume *vcookie)
126{
127 struct cachefiles_volume *volume = vcookie->cache_priv;
128
129 if (volume) {
130 spin_lock(&volume->cache->object_list_lock);
131 list_del_init(&volume->cache_link);
132 spin_unlock(&volume->cache->object_list_lock);
133 __cachefiles_free_volume(volume);
134 }
135}
136
137void cachefiles_withdraw_volume(struct cachefiles_volume *volume)
138{
139 cachefiles_set_volume_xattr(volume);
140 __cachefiles_free_volume(volume);
141}