[Qemu-devel] [PATCH 09/13] block/linux-aio.c: introduce laio_alloc_resource()

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

This patch introduces laio_alloc_resource() for allocating
resources for linux aio, then in the following patchs we
can allocate IO resources just in demand.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 block/linux-aio.c |   55 ++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 20 deletions(-)

diff --git a/block/linux-aio.c b/block/linux-aio.c
index 5be8036..e3e0532 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -73,6 +73,7 @@ struct qemu_laio_state {
 
     /* All BS in the list shared this 'qemu_laio_state' */
     QLIST_HEAD(, LaioTrackedBs) tracked_bs;
+    AioContext *aio_context;
 };
 
 typedef struct {
@@ -380,20 +381,45 @@ out_free_aiocb:
     return NULL;
 }
 
-static LaioQueue *laio_alloc_ioq(AioContext *ctx, struct qemu_laio_state *s)
+static int laio_alloc_resources(AioContext *ctx,
+        struct qemu_laio_state *s)
 {
-    LaioQueue *ioq = g_malloc0(sizeof(*ioq));
+    LaioQueue *ioq;
 
+    if (io_setup(MAX_EVENTS, &s->ctx) != 0) {
+        return -1;
+    }
+
+    ioq = g_malloc0(sizeof(*s->io_q));
     ioq_init(ioq);
     ioq->retry = aio_bh_new(ctx, ioq_submit_retry, s);
-    return ioq;
+
+    s->events = g_malloc(sizeof(*s->events) * MAX_EVENTS);
+    s->io_q = ioq;
+
+    s->completion_bh = aio_bh_new(ctx, qemu_laio_completion_bh, s);
+    aio_set_event_notifier(ctx, &s->e, qemu_laio_completion_cb);
+
+    return 0;
 }
 
-static void laio_free_ioq(struct qemu_laio_state *s, LaioQueue *ioq)
+static void laio_free_resources(struct qemu_laio_state *s)
 {
+    LaioQueue *ioq = s->io_q;
+
+    aio_set_event_notifier(s->aio_context, &s->e, NULL);
+    qemu_bh_delete(s->completion_bh);
+
+    g_free(s->events);
+
     qemu_bh_delete(ioq->retry);
     g_free(ioq);
     s->io_q = NULL;
+
+    if (io_destroy(s->ctx) != 0) {
+        fprintf(stderr, "%s: destroy AIO context %p failed\n",
+                        __func__, &s->ctx);
+    }
 }
 
 static struct qemu_laio_state *laio_state_alloc(AioContext *context)
@@ -405,15 +431,10 @@ static struct qemu_laio_state *laio_state_alloc(AioContext *context)
         goto out_free_state;
     }
 
-    if (io_setup(MAX_EVENTS, &s->ctx) != 0) {
+    if (laio_alloc_resources(context, s) != 0) {
         goto out_close_efd;
     }
 
-    s->events = g_malloc(sizeof(*s->events) * MAX_EVENTS);
-    s->io_q = laio_alloc_ioq(context, s);
-    s->completion_bh = aio_bh_new(context, qemu_laio_completion_bh, s);
-    aio_set_event_notifier(context, &s->e, qemu_laio_completion_cb);
-
     return s;
 
 out_close_efd:
@@ -425,17 +446,8 @@ out_free_state:
 
 static void laio_state_free(struct qemu_laio_state *s, AioContext *context)
 {
-    aio_set_event_notifier(context, &s->e, NULL);
-    qemu_bh_delete(s->completion_bh);
-
-    laio_free_ioq(s, s->io_q);
+    laio_free_resources(s);
     event_notifier_cleanup(&s->e);
-    g_free(s->events);
-
-    if (io_destroy(s->ctx) != 0) {
-        fprintf(stderr, "%s: destroy AIO context %p failed\n",
-                        __func__, &s->ctx);
-    }
     g_free(s);
 }
 
@@ -473,6 +485,9 @@ void laio_attach_aio_context(void *s_, BlockDriverState *bs,
 
     if (aio_attach_aio_bs(new_context, bs)) {
         new_context->opaque = qs->state = laio_state_alloc(new_context);
+
+        /* qemu_laio_state is per AioContext */
+        qs->state->aio_context = new_context;
     } else {
         qs->state = new_context->opaque;
     }
-- 
1.7.9.5