[PATCH 2/6] block/nvme: convert to blk_io_plug_call() API

[Stefan Hajnoczi <stefanha@xxxxxxxxxx>]

Stop using the .bdrv_co_io_plug() API because it is not multi-queue
block layer friendly. Use the new blk_io_plug_call() API to batch I/O
submission instead.

Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
---
 block/nvme.c | 44 ++++++++++++--------------------------------
 1 file changed, 12 insertions(+), 32 deletions(-)

diff --git a/block/nvme.c b/block/nvme.c
index 5b744c2bda..100b38b592 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -25,6 +25,7 @@
 #include "qemu/vfio-helpers.h"
 #include "block/block-io.h"
 #include "block/block_int.h"
+#include "sysemu/block-backend.h"
 #include "sysemu/replay.h"
 #include "trace.h"
 
@@ -119,7 +120,6 @@ struct BDRVNVMeState {
     int blkshift;
 
     uint64_t max_transfer;
-    bool plugged;
 
     bool supports_write_zeroes;
     bool supports_discard;
@@ -282,7 +282,7 @@ static void nvme_kick(NVMeQueuePair *q)
 {
     BDRVNVMeState *s = q->s;
 
-    if (s->plugged || !q->need_kick) {
+    if (!q->need_kick) {
         return;
     }
     trace_nvme_kick(s, q->index);
@@ -387,10 +387,6 @@ static bool nvme_process_completion(NVMeQueuePair *q)
     NvmeCqe *c;
 
     trace_nvme_process_completion(s, q->index, q->inflight);
-    if (s->plugged) {
-        trace_nvme_process_completion_queue_plugged(s, q->index);
-        return false;
-    }
 
     /*
      * Support re-entrancy when a request cb() function invokes aio_poll().
@@ -480,6 +476,15 @@ static void nvme_trace_command(const NvmeCmd *cmd)
     }
 }
 
+static void nvme_unplug_fn(void *opaque)
+{
+    NVMeQueuePair *q = opaque;
+
+    QEMU_LOCK_GUARD(&q->lock);
+    nvme_kick(q);
+    nvme_process_completion(q);
+}
+
 static void nvme_submit_command(NVMeQueuePair *q, NVMeRequest *req,
                                 NvmeCmd *cmd, BlockCompletionFunc cb,
                                 void *opaque)
@@ -496,8 +501,7 @@ static void nvme_submit_command(NVMeQueuePair *q, 
NVMeRequest *req,
            q->sq.tail * NVME_SQ_ENTRY_BYTES, cmd, sizeof(*cmd));
     q->sq.tail = (q->sq.tail + 1) % NVME_QUEUE_SIZE;
     q->need_kick++;
-    nvme_kick(q);
-    nvme_process_completion(q);
+    blk_io_plug_call(nvme_unplug_fn, q);
     qemu_mutex_unlock(&q->lock);
 }
 
@@ -1567,27 +1571,6 @@ static void nvme_attach_aio_context(BlockDriverState *bs,
     }
 }
 
-static void coroutine_fn nvme_co_io_plug(BlockDriverState *bs)
-{
-    BDRVNVMeState *s = bs->opaque;
-    assert(!s->plugged);
-    s->plugged = true;
-}
-
-static void coroutine_fn nvme_co_io_unplug(BlockDriverState *bs)
-{
-    BDRVNVMeState *s = bs->opaque;
-    assert(s->plugged);
-    s->plugged = false;
-    for (unsigned i = INDEX_IO(0); i < s->queue_count; i++) {
-        NVMeQueuePair *q = s->queues[i];
-        qemu_mutex_lock(&q->lock);
-        nvme_kick(q);
-        nvme_process_completion(q);
-        qemu_mutex_unlock(&q->lock);
-    }
-}
-
 static bool nvme_register_buf(BlockDriverState *bs, void *host, size_t size,
                               Error **errp)
 {
@@ -1664,9 +1647,6 @@ static BlockDriver bdrv_nvme = {
     .bdrv_detach_aio_context  = nvme_detach_aio_context,
     .bdrv_attach_aio_context  = nvme_attach_aio_context,
 
-    .bdrv_co_io_plug          = nvme_co_io_plug,
-    .bdrv_co_io_unplug        = nvme_co_io_unplug,
-
     .bdrv_register_buf        = nvme_register_buf,
     .bdrv_unregister_buf      = nvme_unregister_buf,
 };
-- 
2.40.1