On 22.10.25 14:57, Kevin Wolf wrote:
Am 01.07.2025 um 13:44 hat Hanna Czenczek geschrieben:
Make BlockExportType.iothread an alternate between a single-thread
variant 'str' and a multi-threading variant '[str]'.
In contrast to the single-thread setting, the multi-threading setting
will not change the BDS's context (and so is incompatible with the
fixed-iothread setting), but instead just pass a list to the export
driver, with which it can do whatever it wants.
Currently no export driver supports multi-threading, so they all return
an error when receiving such a list.
Suggested-by: Kevin Wolf <[email protected]>
Acked-by: Markus Armbruster <[email protected]>
Reviewed-by: Stefan Hajnoczi <[email protected]>
Signed-off-by: Hanna Czenczek <[email protected]>
diff --git a/include/block/export.h b/include/block/export.h
index 4bd9531d4d..ca45da928c 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -32,8 +32,16 @@ typedef struct BlockExportDriver {
/* True if the export type supports running on an inactive node */
bool supports_inactive;
- /* Creates and starts a new block export */
- int (*create)(BlockExport *, BlockExportOptions *, Error **);
+ /*
+ * Creates and starts a new block export.
+ *
+ * If the user passed a set of I/O threads for multi-threading,
@multithread
+ * is a list of the @multithread_count corresponding contexts (freed by the
+ * caller). Note that @exp->ctx has no relation to that list.
Maybe worth stating that it's NULL in the single threaded case?
I think that’s implicit, but absolutely no harm in being explicit about it.
+ */
+ int (*create)(BlockExport *exp, BlockExportOptions *opts,
+ AioContext *const *multithread, size_t multithread_count,
+ Error **errp);
/*
* Frees a removed block export. This function is only called after all
diff --git a/block/export/export.c b/block/export/export.c
index f3bbf11070..b733f269f3 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -76,16 +76,26 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error
**errp)
{
bool fixed_iothread = export->has_fixed_iothread &&
export->fixed_iothread;
bool allow_inactive = export->has_allow_inactive &&
export->allow_inactive;
+ bool multithread = export->iothread &&
+ export->iothread->type == QTYPE_QLIST;
const BlockExportDriver *drv;
BlockExport *exp = NULL;
BlockDriverState *bs;
BlockBackend *blk = NULL;
AioContext *ctx;
+ AioContext **multithread_ctxs = NULL;
g_autofree?
Sure, why not.
Hanna
