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[Qemu-devel] [PATCH v2 03/12] block: Add "has_single_child" field for dr
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v2 03/12] block: Add "has_single_child" field for drivers |
Date: |
Fri, 7 Mar 2014 23:55:47 +0100 |
This field should be used by block drivers acting as filters which have
only a single child BDS which is referenced through the "file" field of
the BDS.
Setting this field allows other block functions to "access" the child
BDS, for instance in bdrv_recurse_is_first_non_filter(). Therefore, it
should not be set if the block layer should not have access to the child
through the filter.
Signed-off-by: Max Reitz <address@hidden>
---
block.c | 4 ++++
include/block/block_int.h | 7 +++++++
2 files changed, 11 insertions(+)
diff --git a/block.c b/block.c
index 06fbc0a..aec325f 100644
--- a/block.c
+++ b/block.c
@@ -5418,6 +5418,10 @@ bool bdrv_recurse_is_first_non_filter(BlockDriverState
*bs,
return bs->drv->bdrv_recurse_is_first_non_filter(bs, candidate);
}
+ if (bs->drv->has_single_child) {
+ return bdrv_recurse_is_first_non_filter(bs->file, candidate);
+ }
+
/* the driver is a block filter but don't allow to recurse -> return false
*/
return false;
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 4fc5ea8..7815587 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -78,6 +78,13 @@ struct BlockDriver {
/* set to true if the BlockDriver is a block filter */
bool is_filter;
+ /* Set to true if the BlockDriver is a filter with a single child
referenced
+ * through the "file" field in the BDS. This allows the block layer to
+ * access that child through the filter (e.g., for
+ * bdrv_recurse_is_first_non_filter()); if this is not desired, set it to
+ * false (the "file" field should not have been used in this case anyway,
+ * though). */
+ bool has_single_child;
/* for snapshots block filter like Quorum can implement the
* following recursive callback.
* It's purpose is to recurse on the filter children while calling
--
1.9.0
- [Qemu-devel] [PATCH v2 00/12] block/json: Add JSON protocol driver, Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 01/12] qdict: Add qdict_join(), Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 02/12] check-qdict: Add test for qdict_join(), Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 03/12] block: Add "has_single_child" field for drivers,
Max Reitz <=
- [Qemu-devel] [PATCH v2 04/12] block/json: Add JSON protocol driver, Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 05/12] block/json: Add functions for cache control, Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 06/12] block/json: Add functions for writing zeroes etc., Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 07/12] block/json: Add bdrv_co_get_block_status(), Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 08/12] block/json: Add ioctl etc., Max Reitz, 2014/03/07
- [Qemu-devel] [PATCH v2 09/12] block/json: Add bdrv_get_specific_info(), Max Reitz, 2014/03/07