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[PATCH v7 01/15] block: BlockDriver: add .filtered_child_is_backing fiel
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
[PATCH v7 01/15] block: BlockDriver: add .filtered_child_is_backing field |
Date: |
Tue, 26 Jul 2022 23:11:20 +0300 |
Unfortunately not all filters use .file child as filtered child. Two
exclusions are mirror_top and commit_top. Happily they both are private
filters. Bad thing is that this inconsistency is observable through qmp
commands query-block / query-named-block-nodes. So, could we just
change mirror_top and commit_top to use file child as all other filter
driver is an open question. Probably, we could do that with some kind
of deprecation period, but how to warn users during it?
For now, let's just add a field so we can distinguish them in generic
code, it will be used in further commits.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
---
block/commit.c | 1 +
block/mirror.c | 1 +
include/block/block_int-common.h | 13 +++++++++++++
3 files changed, 15 insertions(+)
diff --git a/block/commit.c b/block/commit.c
index 38571510cb..e210e86bac 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -238,6 +238,7 @@ static BlockDriver bdrv_commit_top = {
.bdrv_child_perm = bdrv_commit_top_child_perm,
.is_filter = true,
+ .filtered_child_is_backing = true,
};
void commit_start(const char *job_id, BlockDriverState *bs,
diff --git a/block/mirror.c b/block/mirror.c
index 3c4ab1159d..b808e8bdc2 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1578,6 +1578,7 @@ static BlockDriver bdrv_mirror_top = {
.bdrv_child_perm = bdrv_mirror_top_child_perm,
.is_filter = true,
+ .filtered_child_is_backing = true,
};
static BlockJob *mirror_start_job(
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 8947abab76..9d91ccbcbf 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -119,6 +119,19 @@ struct BlockDriver {
* (And this filtered child must then be bs->file or bs->backing.)
*/
bool is_filter;
+ /*
+ * Only make sense for filter drivers, for others must be false.
+ * If true, filtered child is bs->backing. Otherwise it's bs->file.
+ * Only two internal filters use bs->backing as filtered child and has this
+ * field set to true: mirror_top and commit_top.
+ *
+ * Never create any more such filters!
+ *
+ * TODO: imagine how to deprecate this behavior and make all filters work
+ * similarly using bs->file as filtered child.
+ */
+ bool filtered_child_is_backing;
+
/*
* Set to true if the BlockDriver is a format driver. Format nodes
* generally do not expect their children to be other format nodes
--
2.25.1
- [PATCH v7 for-7.2 00/15] block: cleanup backing and file handling, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 01/15] block: BlockDriver: add .filtered_child_is_backing field,
Vladimir Sementsov-Ogievskiy <=
- [PATCH v7 03/15] block/blklogwrites: don't care to remove bs->file child on failure, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 02/15] block: introduce bdrv_open_file_child() helper, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 04/15] test-bdrv-graph-mod: update test_parallel_perm_update test case, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 05/15] tests-bdrv-drain: bdrv_replace_test driver: declare supports_backing, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 07/15] block: document connection between child roles and bs->backing/bs->file, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 06/15] test-bdrv-graph-mod: fix filters to be filters, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 08/15] block/snapshot: stress that we fallback to primary child, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 10/15] Revert "block: Let replace_child_tran keep indirect pointer", Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 15/15] block: refactor bdrv_remove_file_or_backing_child to bdrv_remove_child, Vladimir Sementsov-Ogievskiy, 2022/07/26
- [PATCH v7 13/15] block: Manipulate bs->file / bs->backing pointers in .attach/.detach, Vladimir Sementsov-Ogievskiy, 2022/07/26