When the child in question already has write access, we shouldn't change
that just because the parent being open/reopen doesn't need it. But if
we are inherenting the flags from a writable parent, we shouldn't copy
the BDRV_O_RDWR flag, which is consistent with the BDRV_OPT_READ_ONLY
option we set.
Signed-off-by: Fam Zheng <f...@redhat.com>
---
block.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/block.c b/block.c
index bedbe208e6..937f9fe159 100644
--- a/block.c
+++ b/block.c
@@ -997,7 +997,10 @@ static void bdrv_backing_options(int *child_flags, QDict
*child_options,
int parent_flags, QDict *parent_options,
int current_flags)
{
- int flags = parent_flags;
+ /* write flag should be preserved if the backing file already has it. This
+ * is important during reopen, to keep "parallel block jobs" work. */
+ int write_flag = current_flags & BDRV_O_RDWR;
+ int flags = parent_flags | write_flag;
/* The cache mode is inherited unmodified for backing files; except WCE,
* which is only applied on the top level (BlockBackend) */
@@ -1005,9 +1008,13 @@ static void bdrv_backing_options(int *child_flags, QDict
*child_options,
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
- /* backing files always opened read-only */
- qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
- flags &= ~BDRV_O_COPY_ON_READ;
+
+ if (!write_flag) {
+ flags &= ~BDRV_O_COPY_ON_READ;
+ /* backing files always opened read-only */
+ qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
+ flags &= ~BDRV_O_RDWR;
+ }
/* snapshot=on is handled on the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_TEMPORARY);
--
2.14.3
