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1 /*
2 * Block node graph modifications tests
3 *
4 * Copyright (c) 2019 Virtuozzo International GmbH. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 *
19 */
20
21 #include "qemu/osdep.h"
22 #include "qapi/error.h"
23 #include "qemu/main-loop.h"
24 #include "block/block_int.h"
25 #include "sysemu/block-backend.h"
26
27 static BlockDriver bdrv_pass_through = {
28 .format_name = "pass-through",
29 .bdrv_child_perm = bdrv_default_perms,
30 };
31
32 static void no_perm_default_perms(BlockDriverState *bs, BdrvChild *c,
33 BdrvChildRole role,
34 BlockReopenQueue *reopen_queue,
35 uint64_t perm, uint64_t shared,
36 uint64_t *nperm, uint64_t *nshared)
37 {
38 *nperm = 0;
39 *nshared = BLK_PERM_ALL;
40 }
41
42 static BlockDriver bdrv_no_perm = {
43 .format_name = "no-perm",
44 .bdrv_child_perm = no_perm_default_perms,
45 };
46
47 static BlockDriverState *no_perm_node(const char *name)
48 {
49 return bdrv_new_open_driver(&bdrv_no_perm, name, BDRV_O_RDWR, &error_abort);
50 }
51
52 static BlockDriverState *pass_through_node(const char *name)
53 {
54 return bdrv_new_open_driver(&bdrv_pass_through, name,
55 BDRV_O_RDWR, &error_abort);
56 }
57
58 /*
59 * test_update_perm_tree
60 *
61 * When checking node for a possibility to update permissions, it's subtree
62 * should be correctly checked too. New permissions for each node should be
63 * calculated and checked in context of permissions of other nodes. If we
64 * check new permissions of the node only in context of old permissions of
65 * its neighbors, we can finish up with wrong permission graph.
66 *
67 * This test firstly create the following graph:
68 * +--------+
69 * | root |
70 * +--------+
71 * |
72 * | perm: write, read
73 * | shared: except write
74 * v
75 * +-------------------+ +----------------+
76 * | passtrough filter |---------->| null-co node |
77 * +-------------------+ +----------------+
78 *
79 *
80 * and then, tries to append filter under node. Expected behavior: fail.
81 * Otherwise we'll get the following picture, with two BdrvChild'ren, having
82 * write permission to one node, without actually sharing it.
83 *
84 * +--------+
85 * | root |
86 * +--------+
87 * |
88 * | perm: write, read
89 * | shared: except write
90 * v
91 * +-------------------+
92 * | passtrough filter |
93 * +-------------------+
94 * | |
95 * perm: write, read | | perm: write, read
96 * shared: except write | | shared: except write
97 * v v
98 * +----------------+
99 * | null co node |
100 * +----------------+
101 */
102 static void test_update_perm_tree(void)
103 {
104 int ret;
105
106 BlockBackend *root = blk_new(qemu_get_aio_context(),
107 BLK_PERM_WRITE | BLK_PERM_CONSISTENT_READ,
108 BLK_PERM_ALL & ~BLK_PERM_WRITE);
109 BlockDriverState *bs = no_perm_node("node");
110 BlockDriverState *filter = pass_through_node("filter");
111
112 blk_insert_bs(root, bs, &error_abort);
113
114 bdrv_attach_child(filter, bs, "child", &child_of_bds,
115 BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, &error_abort);
116
117 ret = bdrv_append(filter, bs, NULL);
118 g_assert_cmpint(ret, <, 0);
119
120 blk_unref(root);
121 }
122
123 /*
124 * test_should_update_child
125 *
126 * Test that bdrv_replace_node, and concretely should_update_child
127 * do the right thing, i.e. not creating loops on the graph.
128 *
129 * The test does the following:
130 * 1. initial graph:
131 *
132 * +------+ +--------+
133 * | root | | filter |
134 * +------+ +--------+
135 * | |
136 * root| target|
137 * v v
138 * +------+ +--------+
139 * | node |<---------| target |
140 * +------+ backing +--------+
141 *
142 * 2. Append @filter above @node. If should_update_child works correctly,
143 * it understands, that backing child of @target should not be updated,
144 * as it will create a loop on node graph. Resulting picture should
145 * be the left one, not the right:
146 *
147 * +------+ +------+
148 * | root | | root |
149 * +------+ +------+
150 * | |
151 * root| root|
152 * v v
153 * +--------+ target +--------+ target
154 * | filter |--------------+ | filter |--------------+
155 * +--------+ | +--------+ |
156 * | | | ^ v
157 * backing| | backing| | +--------+
158 * v v | +-----------| target |
159 * +------+ +--------+ v backing +--------+
160 * | node |<---------| target | +------+
161 * +------+ backing +--------+ | node |
162 * +------+
163 *
164 * (good picture) (bad picture)
165 *
166 */
167 static void test_should_update_child(void)
168 {
169 BlockBackend *root = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
170 BlockDriverState *bs = no_perm_node("node");
171 BlockDriverState *filter = no_perm_node("filter");
172 BlockDriverState *target = no_perm_node("target");
173
174 blk_insert_bs(root, bs, &error_abort);
175
176 bdrv_set_backing_hd(target, bs, &error_abort);
177
178 g_assert(target->backing->bs == bs);
179 bdrv_attach_child(filter, target, "target", &child_of_bds,
180 BDRV_CHILD_DATA, &error_abort);
181 bdrv_append(filter, bs, &error_abort);
182 g_assert(target->backing->bs == bs);
183
184 bdrv_unref(bs);
185 blk_unref(root);
186 }
187
188 int main(int argc, char *argv[])
189 {
190 bdrv_init();
191 qemu_init_main_loop(&error_abort);
192
193 g_test_init(&argc, &argv, NULL);
194
195 g_test_add_func("/bdrv-graph-mod/update-perm-tree", test_update_perm_tree);
196 g_test_add_func("/bdrv-graph-mod/should-update-child",
197 test_should_update_child);
198
199 return g_test_run();
200 }