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}