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[RFC PATCH 6/8] block-backend: implement .change_aio_ctx in child_root
From: |
Emanuele Giuseppe Esposito |
Subject: |
[RFC PATCH 6/8] block-backend: implement .change_aio_ctx in child_root |
Date: |
Tue, 12 Jul 2022 17:19:09 -0400 |
blk_root_change_aio_ctx() is very similar to blk_root_can_set_aio_ctx(),
but implements a new transaction so that if all check pass, the new
transaction's .commit will take care of changing the BlockBackend
AioContext. blk_root_set_aio_ctx_commit() is the same as
blk_root_set_aio_ctx().
Note: bdrv_child_try_change_aio_context() is not called by
anyone at this point.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
block/block-backend.c | 54 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)
diff --git a/block/block-backend.c b/block/block-backend.c
index f425b00793..674eaaa2bf 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -138,6 +138,9 @@ static bool blk_root_can_set_aio_ctx(BdrvChild *child,
AioContext *ctx,
GSList **ignore, Error **errp);
static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore);
+static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
+ GSList **visited, Transaction *tran,
+ Error **errp);
static char *blk_root_get_parent_desc(BdrvChild *child)
{
@@ -336,6 +339,7 @@ static const BdrvChildClass child_root = {
.can_set_aio_ctx = blk_root_can_set_aio_ctx,
.set_aio_ctx = blk_root_set_aio_ctx,
+ .change_aio_ctx = blk_root_change_aio_ctx,
.get_parent_aio_context = blk_root_get_parent_aio_context,
};
@@ -2208,6 +2212,56 @@ int blk_set_aio_context(BlockBackend *blk, AioContext
*new_context,
return blk_do_set_aio_context(blk, new_context, true, errp);
}
+typedef struct BdrvStateBlkRootContext {
+ AioContext *new_ctx;
+ BlockBackend *blk;
+} BdrvStateBlkRootContext;
+
+static void blk_root_set_aio_ctx_commit(void *opaque)
+{
+ BdrvStateBlkRootContext *s = opaque;
+ BlockBackend *blk = s->blk;
+
+ blk_do_set_aio_context(blk, s->new_ctx, false, &error_abort);
+}
+
+static TransactionActionDrv set_blk_root_context = {
+ .commit = blk_root_set_aio_ctx_commit,
+ .clean = g_free,
+};
+
+static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
+ GSList **visited, Transaction *tran,
+ Error **errp)
+{
+ BlockBackend *blk = child->opaque;
+ BdrvStateBlkRootContext *s;
+
+ if (blk->allow_aio_context_change) {
+ goto finish;
+ }
+
+ /*
+ * Only manually created BlockBackends that are not attached to anything
+ * can change their AioContext without updating their user.
+ */
+ if (!blk->name || blk->dev) {
+ /* TODO Add BB name/QOM path */
+ error_setg(errp, "Cannot change iothread of active block backend");
+ return false;
+ }
+
+finish:
+ s = g_new(BdrvStateBlkRootContext, 1);
+ *s = (BdrvStateBlkRootContext) {
+ .new_ctx = ctx,
+ .blk = blk,
+ };
+
+ tran_add_tail(tran, &set_blk_root_context, s);
+ return true;
+}
+
static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore, Error **errp)
{
--
2.31.1