trace: Trace virtio-blk, multiwrite, and paio_submit

This patch adds trace events that make it possible to observe
virtio-blk.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

block.c

@@ -23,6 +23,7 @@
  */
 #include "config-host.h"
 #include "qemu-common.h"
+#include "trace.h"
 #include "monitor.h"
 #include "block_int.h"
 #include "module.h"
@@ -2063,6 +2064,8 @@ static void multiwrite_cb(void *opaque, int ret)
 {
     MultiwriteCB *mcb = opaque;
 
+    trace_multiwrite_cb(mcb, ret);
+
     if (ret < 0 && !mcb->error) {
         mcb->error = ret;
     }
@@ -2203,6 +2206,8 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
     // Check for mergable requests
     num_reqs = multiwrite_merge(bs, reqs, num_reqs, mcb);
 
+    trace_bdrv_aio_multiwrite(mcb, mcb->num_callbacks, num_reqs);
+
     /*
      * Run the aio requests. As soon as one request can't be submitted
      * successfully, fail all requests that are not yet submitted (we must
@@ -2224,6 +2229,7 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
      */
     mcb->num_requests = 1;
 
+    // Run the aio requests
     for (i = 0; i < num_reqs; i++) {
         mcb->num_requests++;
         acb = bdrv_aio_writev(bs, reqs[i].sector, reqs[i].qiov,
@@ -2234,8 +2240,10 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs)
             // submitted yet. Otherwise we'll wait for the submitted AIOs to
             // complete and report the error in the callback.
             if (i == 0) {
+                trace_bdrv_aio_multiwrite_earlyfail(mcb);
                 goto fail;
             } else {
+                trace_bdrv_aio_multiwrite_latefail(mcb, i);
                 multiwrite_cb(mcb, -EIO);
                 break;
             }

hw/virtio-blk.c

@@ -13,6 +13,7 @@
 
 #include <qemu-common.h>
 #include "qemu-error.h"
+#include "trace.h"
 #include "blockdev.h"
 #include "virtio-blk.h"
 #ifdef __linux__
@@ -52,6 +53,8 @@ static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
 {
     VirtIOBlock *s = req->dev;
 
+    trace_virtio_blk_req_complete(req, status);
+
     req->in->status = status;
     virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
     virtio_notify(&s->vdev, s->vq);
@@ -88,6 +91,8 @@ static void virtio_blk_rw_complete(void *opaque, int ret)
 {
     VirtIOBlockReq *req = opaque;
 
+    trace_virtio_blk_rw_complete(req, ret);
+
     if (ret) {
         int is_read = !(req->out->type & VIRTIO_BLK_T_OUT);
         if (virtio_blk_handle_rw_error(req, -ret, is_read))
@@ -270,6 +275,8 @@ static void virtio_blk_handle_write(VirtIOBlockReq *req, MultiReqBuffer *mrb)
 {
     BlockRequest *blkreq;
 
+    trace_virtio_blk_handle_write(req, req->out->sector, req->qiov.size / 512);
+
     if (req->out->sector & req->dev->sector_mask) {
         virtio_blk_rw_complete(req, -EIO);
         return;

posix-aio-compat.c

@@ -25,6 +25,7 @@
 #include "qemu-queue.h"
 #include "osdep.h"
 #include "qemu-common.h"
+#include "trace.h"
 #include "block_int.h"
 
 #include "block/raw-posix-aio.h"
@@ -583,6 +584,7 @@ BlockDriverAIOCB *paio_submit(BlockDriverState *bs, int fd,
     acb->next = posix_aio_state->first_aio;
     posix_aio_state->first_aio = acb;
 
+    trace_paio_submit(acb, opaque, sector_num, nb_sectors, type);
     qemu_paio_submit(acb);
     return &acb->common;
 }

trace-events

@@ -37,3 +37,17 @@ disable qemu_free(void *ptr) "ptr %p"
 disable qemu_memalign(size_t alignment, size_t size, void *ptr) "alignment %zu size %zu ptr %p"
 disable qemu_valloc(size_t size, void *ptr) "size %zu ptr %p"
 disable qemu_vfree(void *ptr) "ptr %p"
+
+# block.c
+disable multiwrite_cb(void *mcb, int ret) "mcb %p ret %d"
+disable bdrv_aio_multiwrite(void *mcb, int num_callbacks, int num_reqs) "mcb %p num_callbacks %d num_reqs %d"
+disable bdrv_aio_multiwrite_earlyfail(void *mcb) "mcb %p"
+disable bdrv_aio_multiwrite_latefail(void *mcb, int i) "mcb %p i %d"
+
+# hw/virtio-blk.c
+disable virtio_blk_req_complete(void *req, int status) "req %p status %d"
+disable virtio_blk_rw_complete(void *req, int ret) "req %p ret %d"
+disable virtio_blk_handle_write(void *req, unsigned long sector, unsigned long nsectors) "req %p sector %lu nsectors %lu"
+
+# posix-aio-compat.c
+disable paio_submit(void *acb, void *opaque, unsigned long sector_num, unsigned long nb_sectors, unsigned long type) "acb %p opaque %p sector_num %lu nb_sectors %lu type %lu"