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From ec5408763c49cd0b63ee324bdc38a429ed1adeee Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 13 Mar 2020 12:34:29 +0000
Subject: [PATCH 09/20] block/qcow2: Move bitmap reopen into
 bdrv_reopen_commit_post

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20200313123439.10548-4-kwolf@redhat.com>
Patchwork-id: 94280
O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH v2 03/13] block/qcow2: Move bitmap reopen into bdrv_reopen_commit_post
Bugzilla: 1790482 1805143
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Daniel P. Berrange <berrange@redhat.com>
RH-Acked-by: Peter Krempa <pkrempa@redhat.com>

From: Peter Krempa <pkrempa@redhat.com>

The bitmap code requires writing the 'file' child when the qcow2 driver
is reopened in read-write mode.

If the 'file' child is being reopened due to a permissions change, the
modification is commited yet when qcow2_reopen_commit is called. This
means that any attempt to write the 'file' child will end with EBADFD
as the original fd was already closed.

Moving bitmap reopening to the new callback which is called after
permission modifications are commited fixes this as the file descriptor
will be replaced with the correct one.

The above problem manifests itself when reopening 'qcow2' format layer
which uses a 'file-posix' file child which was opened with the
'auto-read-only' property set.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Message-Id: <db118dbafe1955afbc0a18d3dd220931074ce349.1582893284.git.pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 65eb7c85a3e62529e2bad782e94d5a7b11dd5a92)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 block/qcow2.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 7c18721..83b1fc0 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1881,6 +1881,11 @@ fail:
 static void qcow2_reopen_commit(BDRVReopenState *state)
 {
     qcow2_update_options_commit(state->bs, state->opaque);
+    g_free(state->opaque);
+}
+
+static void qcow2_reopen_commit_post(BDRVReopenState *state)
+{
     if (state->flags & BDRV_O_RDWR) {
         Error *local_err = NULL;
 
@@ -1895,7 +1900,6 @@ static void qcow2_reopen_commit(BDRVReopenState *state)
                               bdrv_get_node_name(state->bs));
         }
     }
-    g_free(state->opaque);
 }
 
 static void qcow2_reopen_abort(BDRVReopenState *state)
@@ -5492,6 +5496,7 @@ BlockDriver bdrv_qcow2 = {
     .bdrv_close         = qcow2_close,
     .bdrv_reopen_prepare  = qcow2_reopen_prepare,
     .bdrv_reopen_commit   = qcow2_reopen_commit,
+    .bdrv_reopen_commit_post = qcow2_reopen_commit_post,
     .bdrv_reopen_abort    = qcow2_reopen_abort,
     .bdrv_join_options    = qcow2_join_options,
     .bdrv_child_perm      = bdrv_format_default_perms,
-- 
1.8.3.1