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[PATCH 04/21] qdev: allow setting drive property for realized device
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
[PATCH 04/21] qdev: allow setting drive property for realized device |
Date: |
Mon, 17 May 2021 09:44:11 +0300 |
We need an ability to insert filters above top block node, attached to
block device. It can't be achieved with blockdev-reopen command. So, we
want do it with help of qom-set.
Intended usage:
1. blockdev-add, creating the filter, which child is at top node A,
attached to some guest block device.
2. qom-set, to change bs attached to root blk from original node to
newly create filter.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
hw/core/qdev-properties-system.c | 30 ++++++++++++++++++++++--------
1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 2760c21f11..7d97562654 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -93,16 +93,30 @@ static void set_drive_helper(Object *obj, Visitor *v, const
char *name,
BlockBackend *blk;
bool blk_created = false;
int ret;
+ BlockDriverState *bs;
+ AioContext *ctx;
if (!visit_type_str(v, name, &str, errp)) {
return;
}
- /*
- * TODO Should this really be an error? If no, the old value
- * needs to be released before we store the new one.
- */
- if (!check_prop_still_unset(obj, name, *ptr, str, errp)) {
+ if (*ptr) {
+ /* BlockBackend alread exists. So, we want to change attached node */
+ blk = *ptr;
+ ctx = blk_get_aio_context(blk);
+ bs = bdrv_lookup_bs(NULL, str, errp);
+ if (!bs) {
+ return;
+ }
+
+ if (ctx != bdrv_get_aio_context(bs)) {
+ error_setg(errp, "Different aio context is not supported for new "
+ "node");
+ }
+
+ aio_context_acquire(ctx);
+ blk_replace_bs(blk, bs, errp);
+ aio_context_release(ctx);
return;
}
@@ -114,7 +128,7 @@ static void set_drive_helper(Object *obj, Visitor *v, const
char *name,
blk = blk_by_name(str);
if (!blk) {
- BlockDriverState *bs = bdrv_lookup_bs(NULL, str, NULL);
+ bs = bdrv_lookup_bs(NULL, str, NULL);
if (bs) {
/*
* If the device supports iothreads, it will make sure to move the
@@ -123,8 +137,7 @@ static void set_drive_helper(Object *obj, Visitor *v, const
char *name,
* aware of iothreads require their BlockBackends to be in the main
* AioContext.
*/
- AioContext *ctx = iothread ? bdrv_get_aio_context(bs) :
- qemu_get_aio_context();
+ ctx = iothread ? bdrv_get_aio_context(bs) : qemu_get_aio_context();
blk = blk_new(ctx, 0, BLK_PERM_ALL);
blk_created = true;
@@ -196,6 +209,7 @@ static void release_drive(Object *obj, const char *name,
void *opaque)
const PropertyInfo qdev_prop_drive = {
.name = "str",
.description = "Node name or ID of a block device to use as a backend",
+ .realized_set_allowed = true,
.get = get_drive,
.set = set_drive,
.release = release_drive,
--
2.29.2
[PATCH 06/21] block/backup: drop support for copy_range, Vladimir Sementsov-Ogievskiy, 2021/05/17
[PATCH 12/21] block/copy-before-write: bdrv_cbw_append(): replace child at last, Vladimir Sementsov-Ogievskiy, 2021/05/17
[PATCH 11/21] block/copy-before-write: use file child instead of backing, Vladimir Sementsov-Ogievskiy, 2021/05/17