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Blame SOURCES/kvm-test-bdrv-drain-Graph-change-through-parent-callback.patch

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From 58476c0b2e67824bd2108055a315f8b9ebc54e31 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 10 Oct 2018 20:21:42 +0100
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Subject: [PATCH 16/49] test-bdrv-drain: Graph change through parent callback
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20181010202213.7372-4-kwolf@redhat.com>
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Patchwork-id: 82595
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O-Subject: [RHEL-8 qemu-kvm PATCH 13/44] test-bdrv-drain: Graph change through parent callback
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Bugzilla: 1637976
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 231281ab42dad2b407b941e36ad11cbc6586e937)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 tests/test-bdrv-drain.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++
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 1 file changed, 130 insertions(+)
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diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c
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index 38706b0..f786326 100644
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--- a/tests/test-bdrv-drain.c
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+++ b/tests/test-bdrv-drain.c
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@@ -977,6 +977,135 @@ static void test_detach_by_drain_subtree(void)
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 }
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+struct detach_by_parent_data {
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+    BlockDriverState *parent_b;
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+    BdrvChild *child_b;
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+    BlockDriverState *c;
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+    BdrvChild *child_c;
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+};
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+
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+static void detach_by_parent_aio_cb(void *opaque, int ret)
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+{
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+    struct detach_by_parent_data *data = opaque;
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+
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+    g_assert_cmpint(ret, ==, 0);
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+    bdrv_unref_child(data->parent_b, data->child_b);
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+
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+    bdrv_ref(data->c);
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+    data->child_c = bdrv_attach_child(data->parent_b, data->c, "PB-C",
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+                                      &child_file, &error_abort);
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+}
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+
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+/*
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+ * Initial graph:
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+ *
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+ * PA     PB
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+ *    \ /   \
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+ *     A     B     C
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+ *
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+ * PA has a pending write request whose callback changes the child nodes of PB:
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+ * It removes B and adds C instead. The subtree of PB is drained, which will
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+ * indirectly drain the write request, too.
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+ */
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+static void test_detach_by_parent_cb(void)
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+{
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+    BlockBackend *blk;
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+    BlockDriverState *parent_a, *parent_b, *a, *b, *c;
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+    BdrvChild *child_a, *child_b;
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+    BlockAIOCB *acb;
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+    struct detach_by_parent_data data;
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+
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+    QEMUIOVector qiov;
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+    struct iovec iov = {
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+        .iov_base = NULL,
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+        .iov_len = 0,
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+    };
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+    qemu_iovec_init_external(&qiov, &iov, 1);
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+
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+    /* Create all involved nodes */
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+    parent_a = bdrv_new_open_driver(&bdrv_test, "parent-a", BDRV_O_RDWR,
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+                                    &error_abort);
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+    parent_b = bdrv_new_open_driver(&bdrv_test, "parent-b", 0,
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+                                    &error_abort);
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+
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+    a = bdrv_new_open_driver(&bdrv_test, "a", BDRV_O_RDWR, &error_abort);
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+    b = bdrv_new_open_driver(&bdrv_test, "b", BDRV_O_RDWR, &error_abort);
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+    c = bdrv_new_open_driver(&bdrv_test, "c", BDRV_O_RDWR, &error_abort);
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+
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+    /* blk is a BB for parent-a */
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+    blk = blk_new(BLK_PERM_ALL, BLK_PERM_ALL);
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+    blk_insert_bs(blk, parent_a, &error_abort);
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+    bdrv_unref(parent_a);
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+
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+    /* Set child relationships */
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+    bdrv_ref(b);
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+    bdrv_ref(a);
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+    child_b = bdrv_attach_child(parent_b, b, "PB-B", &child_file, &error_abort);
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+    child_a = bdrv_attach_child(parent_b, a, "PB-A", &child_backing, &error_abort);
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+
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+    bdrv_ref(a);
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+    bdrv_attach_child(parent_a, a, "PA-A", &child_file, &error_abort);
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+
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+    g_assert_cmpint(parent_a->refcnt, ==, 1);
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+    g_assert_cmpint(parent_b->refcnt, ==, 1);
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+    g_assert_cmpint(a->refcnt, ==, 3);
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+    g_assert_cmpint(b->refcnt, ==, 2);
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+    g_assert_cmpint(c->refcnt, ==, 1);
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+
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+    g_assert(QLIST_FIRST(&parent_b->children) == child_a);
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+    g_assert(QLIST_NEXT(child_a, next) == child_b);
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+    g_assert(QLIST_NEXT(child_b, next) == NULL);
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+
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+    /* Start the evil write request */
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+    data = (struct detach_by_parent_data) {
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+        .parent_b = parent_b,
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+        .child_b = child_b,
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+        .c = c,
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+    };
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+    acb = blk_aio_preadv(blk, 0, &qiov, 0, detach_by_parent_aio_cb, &data);
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+    g_assert(acb != NULL);
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+
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+    /* Drain and check the expected result */
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+    bdrv_subtree_drained_begin(parent_b);
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+
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+    g_assert(data.child_c != NULL);
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+
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+    g_assert_cmpint(parent_a->refcnt, ==, 1);
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+    g_assert_cmpint(parent_b->refcnt, ==, 1);
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+    g_assert_cmpint(a->refcnt, ==, 3);
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+    g_assert_cmpint(b->refcnt, ==, 1);
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+    g_assert_cmpint(c->refcnt, ==, 2);
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+
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+    g_assert(QLIST_FIRST(&parent_b->children) == data.child_c);
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+    g_assert(QLIST_NEXT(data.child_c, next) == child_a);
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+    g_assert(QLIST_NEXT(child_a, next) == NULL);
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+
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+    g_assert_cmpint(parent_a->quiesce_counter, ==, 1);
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+    g_assert_cmpint(parent_b->quiesce_counter, ==, 1);
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+    g_assert_cmpint(a->quiesce_counter, ==, 1);
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+    g_assert_cmpint(b->quiesce_counter, ==, 0);
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+    g_assert_cmpint(c->quiesce_counter, ==, 1);
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+
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+    bdrv_subtree_drained_end(parent_b);
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+
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+    bdrv_unref(parent_b);
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+    blk_unref(blk);
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+
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+    /* XXX Once bdrv_close() unref's children instead of just detaching them,
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+     * this won't be necessary any more. */
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+    bdrv_unref(a);
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+    bdrv_unref(a);
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+    bdrv_unref(c);
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+
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+    g_assert_cmpint(a->refcnt, ==, 1);
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+    g_assert_cmpint(b->refcnt, ==, 1);
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+    g_assert_cmpint(c->refcnt, ==, 1);
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+    bdrv_unref(a);
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+    bdrv_unref(b);
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+    bdrv_unref(c);
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+}
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+
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+
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 int main(int argc, char **argv)
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 {
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     int ret;
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@@ -1027,6 +1156,7 @@ int main(int argc, char **argv)
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     g_test_add_func("/bdrv-drain/deletion/drain", test_delete_by_drain);
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     g_test_add_func("/bdrv-drain/detach/drain", test_detach_by_drain);
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     g_test_add_func("/bdrv-drain/detach/drain_subtree", test_detach_by_drain_subtree);
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+    g_test_add_func("/bdrv-drain/detach/parent_cb", test_detach_by_parent_cb);
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     ret = g_test_run();
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     qemu_event_destroy(&done_event);
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-- 
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1.8.3.1
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