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 "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     Error *local_err = NULL;
 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     bdrv_append(filter, bs, &local_err);
 118     error_free_or_abort(&local_err);
 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 }