[Qemu-devel] [PATCH 03/13] block/linux-aio: allocate 'struct qemu_laio_state' dynamically

[Ming Lei]

This patch allocates 'struct qemu_laio_state' in aio attach,
and frees it in aio detach, so that in the following patch
we can share one same instance of the structure among multiple
linux-aio backend in same AioContext.

Signed-off-by: Ming Lei <ming....@canonical.com>
---
 block/linux-aio.c |   80 +++++++++++++++++++++++++++++++++++------------------
 1 file changed, 53 insertions(+), 27 deletions(-)

diff --git a/block/linux-aio.c b/block/linux-aio.c
index cf8691e..5fa3c1e 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -52,6 +52,7 @@ typedef struct {
     QEMUBH *retry;
 } LaioQueue;
 
+/* lifetime: between aio_attach and aio_detach */
 struct qemu_laio_state {
     io_context_t ctx;
     EventNotifier e;
@@ -66,6 +67,10 @@ struct qemu_laio_state {
     int event_max;
 };
 
+typedef struct {
+    struct qemu_laio_state *state;
+} QemuLaioState;
+
 static inline ssize_t io_event_ret(struct io_event *ev)
 {
     return (ssize_t)(((uint64_t)ev->res2 << 32) | ev->res);
@@ -277,14 +282,16 @@ static int ioq_enqueue(struct qemu_laio_state *s, struct 
iocb *iocb)
 
 void laio_io_plug(BlockDriverState *bs, void *aio_ctx)
 {
-    struct qemu_laio_state *s = aio_ctx;
+    QemuLaioState *qs = aio_ctx;
+    struct qemu_laio_state *s = qs->state;
 
     s->io_q->plugged++;
 }
 
 int laio_io_unplug(BlockDriverState *bs, void *aio_ctx, bool unplug)
 {
-    struct qemu_laio_state *s = aio_ctx;
+    QemuLaioState *qs = aio_ctx;
+    struct qemu_laio_state *s = qs->state;
     int ret = 0;
 
     assert(s->io_q->plugged > 0 || !unplug);
@@ -304,7 +311,8 @@ BlockAIOCB *laio_submit(BlockDriverState *bs, void 
*aio_ctx, int fd,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
         BlockCompletionFunc *cb, void *opaque, int type)
 {
-    struct qemu_laio_state *s = aio_ctx;
+    QemuLaioState *qs = aio_ctx;
+    struct qemu_laio_state *s = qs->state;
     struct qemu_laiocb *laiocb;
     struct iocb *iocbs;
     off_t offset = sector_num * 512;
@@ -380,27 +388,7 @@ static void laio_free_ioq(struct qemu_laio_state *s, 
LaioQueue *ioq)
     s->io_q = NULL;
 }
 
-void laio_detach_aio_context(void *s_, AioContext *old_context)
-{
-    struct qemu_laio_state *s = s_;
-
-    aio_set_event_notifier(old_context, &s->e, NULL);
-    qemu_bh_delete(s->completion_bh);
-
-    laio_free_ioq(s, s->io_q);
-}
-
-void laio_attach_aio_context(void *s_, AioContext *new_context)
-{
-    struct qemu_laio_state *s = s_;
-
-    s->io_q = laio_alloc_ioq(new_context, s);
-
-    s->completion_bh = aio_bh_new(new_context, qemu_laio_completion_bh, s);
-    aio_set_event_notifier(new_context, &s->e, qemu_laio_completion_cb);
-}
-
-void *laio_init(void)
+static struct qemu_laio_state *laio_state_alloc(void)
 {
     struct qemu_laio_state *s;
 
@@ -422,10 +410,8 @@ out_free_state:
     return NULL;
 }
 
-void laio_cleanup(void *s_)
+static void laio_state_free(struct qemu_laio_state *s)
 {
-    struct qemu_laio_state *s = s_;
-
     event_notifier_cleanup(&s->e);
 
     if (io_destroy(s->ctx) != 0) {
@@ -434,3 +420,43 @@ void laio_cleanup(void *s_)
     }
     g_free(s);
 }
+
+void laio_detach_aio_context(void *s_, AioContext *old_context)
+{
+    QemuLaioState *qs = s_;
+    struct qemu_laio_state *s = qs->state;
+
+    aio_set_event_notifier(old_context, &s->e, NULL);
+    qemu_bh_delete(s->completion_bh);
+
+    laio_free_ioq(s, s->io_q);
+    laio_state_free(s);
+    qs->state = NULL;
+}
+
+void laio_attach_aio_context(void *s_, AioContext *new_context)
+{
+    QemuLaioState *qs = s_;
+    struct qemu_laio_state *s = laio_state_alloc();
+
+    s->io_q = laio_alloc_ioq(new_context, s);
+
+    s->completion_bh = aio_bh_new(new_context, qemu_laio_completion_bh, s);
+    aio_set_event_notifier(new_context, &s->e, qemu_laio_completion_cb);
+
+    qs->state = s;
+}
+
+void *laio_init(void)
+{
+    QemuLaioState *s = g_malloc0(sizeof(*s));
+
+    return s;
+}
+
+void laio_cleanup(void *s_)
+{
+    QemuLaioState *s = s_;
+
+    g_free(s);
+}
-- 
1.7.9.5