From c05f0a720ff742af5c010f5ab2c0661a10cfa536 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 10 Oct 2018 20:08:36 +0100
Subject: [PATCH 05/49] block: Use bdrv_do_drain_begin/end in bdrv_drain_all()

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20181010200843.6710-3-kwolf@redhat.com>
Patchwork-id: 82585
O-Subject: [RHEL-8 qemu-kvm PATCH 02/44] block: Use bdrv_do_drain_begin/end in bdrv_drain_all()
Bugzilla: 1637976
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>

bdrv_do_drain_begin/end() implement already everything that
bdrv_drain_all_begin/end() need and currently still do manually: Disable
external events, call parent drain callbacks, call block driver
callbacks.

It also does two more things:

The first is incrementing bs->quiesce_counter. bdrv_drain_all() already
stood out in the test case by behaving different from the other drain
variants. Adding this is not only safe, but in fact a bug fix.

The second is calling bdrv_drain_recurse(). We already do that later in
the same function in a loop, so basically doing an early first iteration
doesn't hurt.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 79ab8b21dc19c08adc407504e456ff64b9dacb66)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 block/io.c              | 10 ++--------
 tests/test-bdrv-drain.c | 14 ++++----------
 2 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/block/io.c b/block/io.c
index 7e0a169..230b551 100644
--- a/block/io.c
+++ b/block/io.c
@@ -412,11 +412,8 @@ void bdrv_drain_all_begin(void)
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
-        /* Stop things in parent-to-child order */
         aio_context_acquire(aio_context);
-        aio_disable_external(aio_context);
-        bdrv_parent_drained_begin(bs, NULL);
-        bdrv_drain_invoke(bs, true, true);
+        bdrv_do_drained_begin(bs, true, NULL);
         aio_context_release(aio_context);
 
         if (!g_slist_find(aio_ctxs, aio_context)) {
@@ -457,11 +454,8 @@ void bdrv_drain_all_end(void)
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
-        /* Re-enable things in child-to-parent order */
         aio_context_acquire(aio_context);
-        bdrv_drain_invoke(bs, false, true);
-        bdrv_parent_drained_end(bs, NULL);
-        aio_enable_external(aio_context);
+        bdrv_do_drained_end(bs, true, NULL);
         aio_context_release(aio_context);
     }
 }
diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c
index dee0a10..f1276a1 100644
--- a/tests/test-bdrv-drain.c
+++ b/tests/test-bdrv-drain.c
@@ -276,8 +276,7 @@ static void test_quiesce_common(enum drain_type drain_type, bool recursive)
 
 static void test_quiesce_drain_all(void)
 {
-    // XXX drain_all doesn't quiesce
-    //test_quiesce_common(BDRV_DRAIN_ALL, true);
+    test_quiesce_common(BDRV_DRAIN_ALL, true);
 }
 
 static void test_quiesce_drain(void)
@@ -319,12 +318,7 @@ static void test_nested(void)
 
     for (outer = 0; outer < DRAIN_TYPE_MAX; outer++) {
         for (inner = 0; inner < DRAIN_TYPE_MAX; inner++) {
-            /* XXX bdrv_drain_all() doesn't increase the quiesce_counter */
-            int bs_quiesce      = (outer != BDRV_DRAIN_ALL) +
-                                  (inner != BDRV_DRAIN_ALL);
-            int backing_quiesce = (outer == BDRV_SUBTREE_DRAIN) +
-                                  (inner == BDRV_SUBTREE_DRAIN);
-            int backing_cb_cnt  = (outer != BDRV_DRAIN) +
+            int backing_quiesce = (outer != BDRV_DRAIN) +
                                   (inner != BDRV_DRAIN);
 
             g_assert_cmpint(bs->quiesce_counter, ==, 0);
@@ -335,10 +329,10 @@ static void test_nested(void)
             do_drain_begin(outer, bs);
             do_drain_begin(inner, bs);
 
-            g_assert_cmpint(bs->quiesce_counter, ==, bs_quiesce);
+            g_assert_cmpint(bs->quiesce_counter, ==, 2);
             g_assert_cmpint(backing->quiesce_counter, ==, backing_quiesce);
             g_assert_cmpint(s->drain_count, ==, 2);
-            g_assert_cmpint(backing_s->drain_count, ==, backing_cb_cnt);
+            g_assert_cmpint(backing_s->drain_count, ==, backing_quiesce);
 
             do_drain_end(inner, bs);
             do_drain_end(outer, bs);
-- 
1.8.3.1