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[Qemu-devel] [PATCH v5 05/42] block: Add chain helper functions
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v5 05/42] block: Add chain helper functions |
Date: |
Thu, 13 Jun 2019 00:09:27 +0200 |
Add some helper functions for skipping filters in a chain of block
nodes.
Signed-off-by: Max Reitz <address@hidden>
---
include/block/block_int.h | 3 +++
block.c | 55 +++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 7ce71623f8..875a33f255 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -1264,6 +1264,9 @@ BdrvChild *bdrv_filtered_child(BlockDriverState *bs);
BdrvChild *bdrv_metadata_child(BlockDriverState *bs);
BdrvChild *bdrv_storage_child(BlockDriverState *bs);
BdrvChild *bdrv_primary_child(BlockDriverState *bs);
+BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs);
+BlockDriverState *bdrv_skip_rw_filters(BlockDriverState *bs);
+BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs);
static inline BlockDriverState *child_bs(BdrvChild *child)
{
diff --git a/block.c b/block.c
index 724d8889a6..be18130944 100644
--- a/block.c
+++ b/block.c
@@ -6494,3 +6494,58 @@ BdrvChild *bdrv_primary_child(BlockDriverState *bs)
{
return bdrv_filtered_rw_child(bs) ?: bs->file;
}
+
+static BlockDriverState *bdrv_skip_filters(BlockDriverState *bs,
+ bool stop_on_explicit_filter)
+{
+ BdrvChild *filtered;
+
+ if (!bs) {
+ return NULL;
+ }
+
+ while (!(stop_on_explicit_filter && !bs->implicit)) {
+ filtered = bdrv_filtered_rw_child(bs);
+ if (!filtered) {
+ break;
+ }
+ bs = filtered->bs;
+ }
+ /*
+ * Note that this treats nodes with bs->drv == NULL as not being
+ * R/W filters (bs->drv == NULL should be replaced by something
+ * else anyway).
+ * The advantage of this behavior is that this function will thus
+ * always return a non-NULL value (given a non-NULL @bs).
+ */
+
+ return bs;
+}
+
+/*
+ * Return the first BDS that has not been added implicitly or that
+ * does not have an RW-filtered child down the chain starting from @bs
+ * (including @bs itself).
+ */
+BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
+{
+ return bdrv_skip_filters(bs, true);
+}
+
+/*
+ * Return the first BDS that does not have an RW-filtered child down
+ * the chain starting from @bs (including @bs itself).
+ */
+BlockDriverState *bdrv_skip_rw_filters(BlockDriverState *bs)
+{
+ return bdrv_skip_filters(bs, false);
+}
+
+/*
+ * For a backing chain, return the first non-filter backing image of
+ * the first non-filter image.
+ */
+BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
+{
+ return
bdrv_skip_rw_filters(bdrv_filtered_cow_bs(bdrv_skip_rw_filters(bs)));
+}
--
2.21.0