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