From 00ff7ffd67c50fe45a1e313765d416d082541128 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Wed, 13 May 2020 13:05:21 +0200 Subject: [PATCH] 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 Message-Id: <20200513110544.176672-12-mreitz@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- block.c | 71 ++++++++++++++++++----------------------------------------------- 1 file changed, 19 insertions(+), 52 deletions(-) diff --git a/block.c b/block.c index 9b0e13d537..b3b978a092 100644 --- a/block.c +++ b/block.c @@ -80,6 +80,11 @@ static BlockDriverState *bdrv_open_inherit(const char *filename, 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 @@ static void bdrv_protocol_options(BdrvChildRole role, bool parent_is_format, 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 @@ static void bdrv_inherited_fmt_options(BdrvChildRole role, 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 @@ static void bdrv_backing_options(BdrvChildRole role, bool parent_is_format, 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 @@ const BdrvChildClass child_backing = { * 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 @@ static BlockDriverState *bdrv_open_inherit(const char *filename, 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; -- 2.11.0