Reopen flags are not synchronized according to the
bdrv_reopen_queue_child precedence until bdrv_reopen_prepare. It is a
bit too late: we already check the consistency in bdrv_check_perm before
that.

This fixes the bug that when bdrv_reopen a RO node as RW, the flags for
backing child are wrong. Before, we could recurse with flags.rw=1; now,
role->inherit_options + update_flags_from_options will make sure to
clear the bit when necessary.  Note that this will not clear an
explicitly set bit, as in the case of parallel block jobs (e.g.
test_stream_parallel in 030), because the explicit options include
'read-only=false' (for an intermediate node used by a different job).

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/block.c b/block.c
index 75a9fd49de..a121d2ebcc 100644
--- a/block.c
+++ b/block.c
@@ -2883,8 +2883,15 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
 
     /* Inherit from parent node */
     if (parent_options) {
+        QemuOpts *opts;
+        QDict *options_copy;
         assert(!flags);
         role->inherit_options(&flags, options, parent_flags, parent_options);
+        options_copy = qdict_clone_shallow(options);
+        opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
+        qemu_opts_absorb_qdict(opts, options_copy, NULL);
+        update_flags_from_options(&flags, opts);
+        qemu_opts_del(opts);
     }
 
     /* Old values are used for options that aren't set yet */
-- 
2.14.3

Am 13.03.2018 um 15:20 hat Fam Zheng geschrieben:
> Reopen flags are not synchronized according to the
> bdrv_reopen_queue_child precedence until bdrv_reopen_prepare. It is a
> bit too late: we already check the consistency in bdrv_check_perm before
> that.
> 
> This fixes the bug that when bdrv_reopen a RO node as RW, the flags for
> backing child are wrong. Before, we could recurse with flags.rw=1; now,
> role->inherit_options + update_flags_from_options will make sure to
> clear the bit when necessary.  Note that this will not clear an
> explicitly set bit, as in the case of parallel block jobs (e.g.
> test_stream_parallel in 030), because the explicit options include
> 'read-only=false' (for an intermediate node used by a different job).
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/block.c b/block.c
> index 75a9fd49de..a121d2ebcc 100644
> --- a/block.c
> +++ b/block.c
> @@ -2883,8 +2883,15 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
>  
>      /* Inherit from parent node */
>      if (parent_options) {
> +        QemuOpts *opts;
> +        QDict *options_copy;
>          assert(!flags);
>          role->inherit_options(&flags, options, parent_flags, parent_options);
> +        options_copy = qdict_clone_shallow(options);
> +        opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
> +        qemu_opts_absorb_qdict(opts, options_copy, NULL);
> +        update_flags_from_options(&flags, opts);
> +        qemu_opts_del(opts);

Squashed in a line here after Fam and Max agreed on IRC:

+        QDECREF(options_copy);

>      }
>  
>      /* Old values are used for options that aren't set yet */

Kevin