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 */
17void 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
47retry:
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
93error_fan:
94	for (i = 0; i < 256; i++)
95		cachefiles_put_directory(volume->fanout[i]);
96error_dir:
97	cachefiles_put_directory(volume->dentry);
98error_name:
99	kfree(name);
100error_vol:
101	kfree(volume);
102	cachefiles_end_secure(cache, saved_cred);
103}
104
105/*
106 * Release a volume representation.
107 */
108static 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
122void 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
134void cachefiles_withdraw_volume(struct cachefiles_volume *volume)
135{
136	fscache_withdraw_volume(volume->vcookie);
137	cachefiles_set_volume_xattr(volume);
138	__cachefiles_free_volume(volume);
139}
140