[Qemu-devel] [PATCH 07/13] block/linux-aio: support IO submission as batch in AioContext wide

[Ming Lei <ming.lei@canonical.com>]

This patch supports IO submission as batch in AioContext wide
by sharing 'struct qemu_laio_state' instance among all linux-aio
backend in same AioContext.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 block/linux-aio.c |   36 ++++++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/block/linux-aio.c b/block/linux-aio.c
index 17de2e3..c5c7944 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -52,6 +52,11 @@ typedef struct {
     QEMUBH *retry;
 } LaioQueue;
 
+typedef struct LaioTrackedBs {
+    BlockDriverState *bs;
+    QLIST_ENTRY(LaioTrackedBs) list;
+} LaioTrackedBs;
+
 /* lifetime: between aio_attach and aio_detach */
 struct qemu_laio_state {
     io_context_t ctx;
@@ -65,6 +70,9 @@ struct qemu_laio_state {
     struct io_event events[MAX_EVENTS];
     int event_idx;
     int event_max;
+
+    /* All BS in the list shared this 'qemu_laio_state' */
+    QLIST_HEAD(, LaioTrackedBs) tracked_bs;
 };
 
 typedef struct {
@@ -433,6 +441,23 @@ void laio_detach_aio_context(void *s_, BlockDriverState *bs,
         AioContext *old_context)
 {
     QemuLaioState *qs = s_;
+    LaioTrackedBs *tbs, *ntbs;
+
+    QLIST_FOREACH_SAFE(tbs, &qs->state->tracked_bs, list, ntbs) {
+        if (tbs->bs == bs) {
+            QLIST_REMOVE(tbs, list);
+            g_free(tbs);
+        }
+    }
+
+    if (!aio_detach_aio_bs(old_context, bs)) {
+        /* assign new master aio bs for the aio context */
+        if (old_context->master_aio_bs == bs) {
+            tbs = QLIST_FIRST(&qs->state->tracked_bs);
+            old_context->master_aio_bs = tbs->bs;
+        }
+        return;
+    }
 
     laio_state_free(qs->state, old_context);
     qs->state = NULL;
@@ -442,9 +467,16 @@ void laio_attach_aio_context(void *s_, BlockDriverState *bs,
         AioContext *new_context)
 {
     QemuLaioState *qs = s_;
-    struct qemu_laio_state *s = laio_state_alloc(new_context);
+    LaioTrackedBs *tbs = g_malloc0(sizeof(*tbs));
+
+    if (aio_attach_aio_bs(new_context, bs)) {
+        new_context->opaque = qs->state = laio_state_alloc(new_context);
+    } else {
+        qs->state = new_context->opaque;
+    }
 
-    qs->state = s;
+    tbs->bs = bs;
+    QLIST_INSERT_HEAD(&qs->state->tracked_bs, tbs, list);
 }
 
 void *laio_init(void)
-- 
1.7.9.5