[RFC 14/24] block/block-copy: More explicit call_state

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Refactor common path to use BlockCopyCallState pointer as parameter, to
prepare it for use in asynchronous block-copy (at least, we'll need to
run block-copy in a coroutine, passing the whole parameters as one
pointer).

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/block-copy.c | 50 +++++++++++++++++++++++++++++++++++-----------
 1 file changed, 38 insertions(+), 12 deletions(-)

diff --git a/block/block-copy.c b/block/block-copy.c
index b2e7825b53..4b1a0cecbd 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -28,7 +28,15 @@
 #define BLOCK_COPY_MAX_WORKERS 64
 
 typedef struct BlockCopyCallState {
+    /* IN parameters */
+    BlockCopyState *s;
+    int64_t offset;
+    int64_t bytes;
+
+    /* State */
     bool failed;
+
+    /* OUT parameters */
     bool error_is_read;
 } BlockCopyCallState;
 
@@ -514,14 +522,16 @@ int64_t block_copy_reset_unallocated(BlockCopyState *s,
  * Returns 1 if dirty clusters found and successfully copied, 0 if no dirty
  * clusters found and -errno on failure.
  */
-static int coroutine_fn block_copy_dirty_clusters(BlockCopyState *s,
-                                                  int64_t offset, int64_t bytes,
-                                                  bool *error_is_read)
+static int coroutine_fn
+block_copy_dirty_clusters(BlockCopyCallState *call_state)
 {
+    BlockCopyState *s = call_state->s;
+    int64_t offset = call_state->offset;
+    int64_t bytes = call_state->bytes;
+
     int ret = 0;
     bool found_dirty = false;
     AioTaskPool *aio = NULL;
-    BlockCopyCallState call_state = {false, false};
 
     /*
      * block_copy() user is responsible for keeping source and target in same
@@ -546,7 +556,7 @@ static int coroutine_fn block_copy_dirty_clusters(BlockCopyState *s,
 
         found_dirty = true;
 
-        task = block_copy_task_create(s, &call_state, offset, bytes);
+        task = block_copy_task_create(s, call_state, offset, bytes);
 
         ret = block_copy_block_status(s, offset, task->bytes, &status_bytes);
         block_copy_task_shrink(task, status_bytes);
@@ -586,18 +596,14 @@ out:
         }
         g_free(aio);
     }
-    if (error_is_read && ret < 0) {
-        *error_is_read = call_state.error_is_read;
-    }
 
     return ret < 0 ? ret : found_dirty;
 }
 
-int coroutine_fn block_copy(BlockCopyState *s, int64_t start, uint64_t bytes,
-                            bool *error_is_read)
+static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
 {
     while (true) {
-        int ret = block_copy_dirty_clusters(s, start, bytes, error_is_read);
+        int ret = block_copy_dirty_clusters(call_state);
 
         if (ret < 0) {
             /*
@@ -620,7 +626,9 @@ int coroutine_fn block_copy(BlockCopyState *s, int64_t start, uint64_t bytes,
          * requested region.
          */
 
-        if (!block_copy_wait_one(s, start, bytes)) {
+        if (!block_copy_wait_one(call_state->s, call_state->offset,
+                                 call_state->bytes))
+        {
             /* No dirty bits and nothing to wait: the whole request is done */
             break;
         }
@@ -629,6 +637,24 @@ int coroutine_fn block_copy(BlockCopyState *s, int64_t start, uint64_t bytes,
     return 0;
 }
 
+int coroutine_fn block_copy(BlockCopyState *s, int64_t start, uint64_t bytes,
+                            bool *error_is_read)
+{
+    BlockCopyCallState call_state = {
+        .s = s,
+        .offset = start,
+        .bytes = bytes,
+    };
+
+    int ret = block_copy_common(&call_state);
+
+    if (error_is_read && ret < 0) {
+        *error_is_read = call_state.error_is_read;
+    }
+
+    return ret;
+}
+
 BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s)
 {
     return s->copy_bitmap;
-- 
2.21.0