block: Use bdrv_inherited_options()
Let child_file's, child_format's, and child_backing's .inherit_options()
implementations fall back to bdrv_inherited_options() to show that it
would really work for all of these cases, if only the parents passed the
appropriate BdrvChildRole and parent_is_format values.
(Also, make bdrv_open_inherit(), the only place to explicitly call
bdrv_backing_options(), call bdrv_inherited_options() instead.)
This patch should incur only two visible changes, both for child_format
children, both of which are effectively bug fixes:
First, they no longer have discard=unmap set by default. This reason it
was set is because bdrv_inherited_fmt_options() fell through to
bdrv_protocol_options(), and that set it because "format drivers take
care to send flushes and respect unmap policy". None of the drivers
that use child_format for their children (quorum and blkverify) are
format drivers, though, so this reasoning does not apply here.
Second, they no longer have BDRV_O_NO_IO force-cleared. child_format
was used solely for children that do not store any metadata and as such
will not be accessed by their parents as long as those parents do not
receive I/O themselves. Thus, such children should inherit
BDRV_O_NO_IO.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200513110544.176672-12-mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block.c b/block.c
index 9b0e13d..b3b978a 100644
--- a/block.c
+++ b/block.c
@@ -80,6 +80,11 @@
BdrvChildRole child_role,
Error **errp);
+/* TODO: Remove when no longer needed */
+static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
+ int *child_flags, QDict *child_options,
+ int parent_flags, QDict *parent_options);
+
/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;
@@ -1158,31 +1163,9 @@
int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
- int flags = parent_flags;
-
- /* Enable protocol handling, disable format probing for bs->file */
- flags |= BDRV_O_PROTOCOL;
-
- /* If the cache mode isn't explicitly set, inherit direct and no-flush from
- * the parent. */
- qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
- qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
- qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
-
- /* Inherit the read-only option from the parent if it's not set */
- qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
- qdict_copy_default(child_options, parent_options, BDRV_OPT_AUTO_READ_ONLY);
-
- /* Our block drivers take care to send flushes and respect unmap policy,
- * so we can default to enable both on lower layers regardless of the
- * corresponding parent options. */
- qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
-
- /* Clear flags that only apply to the top layer */
- flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ |
- BDRV_O_NO_IO);
-
- *child_flags = flags;
+ bdrv_inherited_options(BDRV_CHILD_IMAGE, true,
+ child_flags, child_options,
+ parent_flags, parent_options);
}
const BdrvChildClass child_file = {
@@ -1209,11 +1192,9 @@
int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
- child_file.inherit_options(role, parent_is_format,
- child_flags, child_options,
- parent_flags, parent_options);
-
- *child_flags &= ~(BDRV_O_PROTOCOL | BDRV_O_NO_IO);
+ bdrv_inherited_options(BDRV_CHILD_DATA, false,
+ child_flags, child_options,
+ parent_flags, parent_options);
}
const BdrvChildClass child_format = {
@@ -1295,23 +1276,9 @@
int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
- int flags = parent_flags;
-
- /* The cache mode is inherited unmodified for backing files; except WCE,
- * which is only applied on the top level (BlockBackend) */
- qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
- 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");
- qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
- flags &= ~BDRV_O_COPY_ON_READ;
-
- /* snapshot=on is handled on the top layer */
- flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_TEMPORARY);
-
- *child_flags = flags;
+ bdrv_inherited_options(BDRV_CHILD_COW, true,
+ child_flags, child_options,
+ parent_flags, parent_options);
}
static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
@@ -1360,10 +1327,9 @@
* Returns the options and flags that a generic child of a BDS should
* get, based on the given options and flags for the parent BDS.
*/
-static void __attribute__((unused))
- bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
- int *child_flags, QDict *child_options,
- int parent_flags, QDict *parent_options)
+static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
+ int *child_flags, QDict *child_options,
+ int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
@@ -3300,7 +3266,8 @@
flags, options);
/* Let bdrv_backing_options() override "read-only" */
qdict_del(options, BDRV_OPT_READ_ONLY);
- bdrv_backing_options(0, true, &flags, options, flags, options);
+ bdrv_inherited_options(BDRV_CHILD_COW, true,
+ &flags, options, flags, options);
}
bs->open_flags = flags;
