tests/test-bdrv-graph-mod.c

   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 "block/block_int.h"
  24 #include "sysemu/block-backend.h"
  25
  26 static BlockDriver bdrv_pass_through = {
  27     .format_name = "pass-through",
  28     .bdrv_child_perm = bdrv_filter_default_perms,
  29 };
  30
  31 static void no_perm_default_perms(BlockDriverState *bs, BdrvChild *c,
  32                                          const BdrvChildRole *role,
  33                                          BlockReopenQueue *reopen_queue,
  34                                          uint64_t perm, uint64_t shared,
  35                                          uint64_t *nperm, uint64_t *nshared)
  36 {
  37     *nperm = 0;
  38     *nshared = BLK_PERM_ALL;
  39 }
  40
  41 static BlockDriver bdrv_no_perm = {
  42     .format_name = "no-perm",
  43     .bdrv_child_perm = no_perm_default_perms,
  44 };
  45
  46 static BlockDriverState *no_perm_node(const char *name)
  47 {
  48     return bdrv_new_open_driver(&bdrv_no_perm, name, BDRV_O_RDWR, &error_abort);
  49 }
  50
  51 static BlockDriverState *pass_through_node(const char *name)
  52 {
  53     return bdrv_new_open_driver(&bdrv_pass_through, name,
  54                                 BDRV_O_RDWR, &error_abort);
  55 }
  56
  57 /*
  58  * test_update_perm_tree
  59  *
  60  * When checking node for a possibility to update permissions, it's subtree
  61  * should be correctly checked too. New permissions for each node should be
  62  * calculated and checked in context of permissions of other nodes. If we
  63  * check new permissions of the node only in context of old permissions of
  64  * its neighbors, we can finish up with wrong permission graph.
  65  *
  66  * This test firstly create the following graph:
  67  *                                +--------+
  68  *                                |  root  |
  69  *                                +--------+
  70  *                                    |
  71  *                                    | perm: write, read
  72  *                                    | shared: except write
  73  *                                    v
  74  *  +-------------------+           +----------------+
  75  *  | passtrough filter |---------->|  null-co node  |
  76  *  +-------------------+           +----------------+
  77  *
  78  *
  79  * and then, tries to append filter under node. Expected behavior: fail.
  80  * Otherwise we'll get the following picture, with two BdrvChild'ren, having
  81  * write permission to one node, without actually sharing it.
  82  *
  83  *                     +--------+
  84  *                     |  root  |
  85  *                     +--------+
  86  *                         |
  87  *                         | perm: write, read
  88  *                         | shared: except write
  89  *                         v
  90  *                +-------------------+
  91  *                | passtrough filter |
  92  *                +-------------------+
  93  *                       |   |
  94  *     perm: write, read |   | perm: write, read
  95  *  shared: except write |   | shared: except write
  96  *                       v   v
  97  *                +----------------+
  98  *                |  null co node  |
  99  *                +----------------+
 100  */
 101 static void test_update_perm_tree(void)
 102 {
 103     Error *local_err = NULL;
 104
 105     BlockBackend *root = blk_new(BLK_PERM_WRITE | BLK_PERM_CONSISTENT_READ,
 106                                  BLK_PERM_ALL & ~BLK_PERM_WRITE);
 107     BlockDriverState *bs = no_perm_node("node");
 108     BlockDriverState *filter = pass_through_node("filter");
 109
 110     blk_insert_bs(root, bs, &error_abort);
 111
 112     bdrv_attach_child(filter, bs, "child", &child_file, &error_abort);
 113
 114     bdrv_append(filter, bs, &local_err);
 115
 116     g_assert_nonnull(local_err);
 117     error_free(local_err);
 118
 119     blk_unref(root);
 120 }
 121
 122 /*
 123  * test_should_update_child
 124  *
 125  * Test that bdrv_replace_node, and concretely should_update_child
 126  * do the right thing, i.e. not creating loops on the graph.
 127  *
 128  * The test does the following:
 129  * 1. initial graph:
 130  *
 131  *   +------+          +--------+
 132  *   | root |          | filter |
 133  *   +------+          +--------+
 134  *      |                  |
 135  *  root|            target|
 136  *      v                  v
 137  *   +------+          +--------+
 138  *   | node |<---------| target |
 139  *   +------+  backing +--------+
 140  *
 141  * 2. Append @filter above @node. If should_update_child works correctly,
 142  * it understands, that backing child of @target should not be updated,
 143  * as it will create a loop on node graph. Resulting picture should
 144  * be the left one, not the right:
 145  *
 146  *     +------+                            +------+
 147  *     | root |                            | root |
 148  *     +------+                            +------+
 149  *        |                                   |
 150  *    root|                               root|
 151  *        v                                   v
 152  *    +--------+   target                 +--------+   target
 153  *    | filter |--------------+           | filter |--------------+
 154  *    +--------+              |           +--------+              |
 155  *        |                   |               |  ^                v
 156  * backing|                   |        backing|  |           +--------+
 157  *        v                   v               |  +-----------| target |
 158  *     +------+          +--------+           v      backing +--------+
 159  *     | node |<---------| target |        +------+
 160  *     +------+  backing +--------+        | node |
 161  *                                         +------+
 162  *
 163  *    (good picture)                       (bad picture)
 164  *
 165  */
 166 static void test_should_update_child(void)
 167 {
 168     BlockBackend *root = blk_new(0, BLK_PERM_ALL);
 169     BlockDriverState *bs = no_perm_node("node");
 170     BlockDriverState *filter = no_perm_node("filter");
 171     BlockDriverState *target = no_perm_node("target");
 172
 173     blk_insert_bs(root, bs, &error_abort);
 174
 175     bdrv_set_backing_hd(target, bs, &error_abort);
 176
 177     g_assert(target->backing->bs == bs);
 178     bdrv_attach_child(filter, target, "target", &child_file, &error_abort);
 179     bdrv_append(filter, bs, &error_abort);
 180     g_assert(target->backing->bs == bs);
 181
 182     bdrv_unref(bs);
 183     blk_unref(root);
 184 }
 185
 186 int main(int argc, char *argv[])
 187 {
 188     bdrv_init();
 189     qemu_init_main_loop(&error_abort);
 190
 191     g_test_init(&argc, &argv, NULL);
 192
 193     g_test_add_func("/bdrv-graph-mod/update-perm-tree", test_update_perm_tree);
 194     g_test_add_func("/bdrv-graph-mod/should-update-child",
 195                     test_should_update_child);
 196
 197     return g_test_run();
 198 }