block/backup: move in-flight requests handling from backup to block-copy

Move synchronization mechanism to block-copy, to be able to use one
block-copy instance from backup job and backup-top filter in parallel.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20191001131409.14202-2-vsementsov@virtuozzo.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/block/block-copy.c b/block/block-copy.c
index 3fc9152853..61e5ea5f46 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -19,6 +19,41 @@
 #include "block/block-copy.h"
 #include "sysemu/block-backend.h"
 
+static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s,
+                                                       int64_t start,
+                                                       int64_t end)
+{
+    BlockCopyInFlightReq *req;
+    bool waited;
+
+    do {
+        waited = false;
+        QLIST_FOREACH(req, &s->inflight_reqs, list) {
+            if (end > req->start_byte && start < req->end_byte) {
+                qemu_co_queue_wait(&req->wait_queue, NULL);
+                waited = true;
+                break;
+            }
+        }
+    } while (waited);
+}
+
+static void block_copy_inflight_req_begin(BlockCopyState *s,
+                                          BlockCopyInFlightReq *req,
+                                          int64_t start, int64_t end)
+{
+    req->start_byte = start;
+    req->end_byte = end;
+    qemu_co_queue_init(&req->wait_queue);
+    QLIST_INSERT_HEAD(&s->inflight_reqs, req, list);
+}
+
+static void coroutine_fn block_copy_inflight_req_end(BlockCopyInFlightReq *req)
+{
+    QLIST_REMOVE(req, list);
+    qemu_co_queue_restart_all(&req->wait_queue);
+}
+
 void block_copy_state_free(BlockCopyState *s)
 {
     if (!s) {
@@ -79,6 +114,8 @@ BlockCopyState *block_copy_state_new(
     s->use_copy_range =
         !(write_flags & BDRV_REQ_WRITE_COMPRESSED) && s->copy_range_size > 0;
 
+    QLIST_INIT(&s->inflight_reqs);
+
     /*
      * We just allow aio context change on our block backends. block_copy() user
      * (now it's only backup) is responsible for source and target being in same
@@ -266,6 +303,7 @@ int coroutine_fn block_copy(BlockCopyState *s,
     int64_t end = bytes + start; /* bytes */
     void *bounce_buffer = NULL;
     int64_t status_bytes;
+    BlockCopyInFlightReq req;
 
     /*
      * block_copy() user is responsible for keeping source and target in same
@@ -276,6 +314,9 @@ int coroutine_fn block_copy(BlockCopyState *s,
     assert(QEMU_IS_ALIGNED(start, s->cluster_size));
     assert(QEMU_IS_ALIGNED(end, s->cluster_size));
 
+    block_copy_wait_inflight_reqs(s, start, bytes);
+    block_copy_inflight_req_begin(s, &req, start, end);
+
     while (start < end) {
         int64_t dirty_end;
 
@@ -329,5 +370,7 @@ int coroutine_fn block_copy(BlockCopyState *s,
         qemu_vfree(bounce_buffer);
     }
 
+    block_copy_inflight_req_end(&req);
+
     return ret;
 }