[Qemu-devel] [PATCH 03/17] mirror: Pull *_align_for_copy() from *_co_read()

[Max Reitz]

Signed-off-by: Max Reitz <address@hidden>
---
 block/mirror.c | 54 +++++++++++++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 18 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index c28b6159d5..34cb8293b2 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -305,42 +305,60 @@ static inline void coroutine_fn
     mirror_co_wait_for_any_operation(s, false);
 }
 
-/* Perform a mirror copy operation.
+/*
+ * Restrict *bytes to how much we can actually handle, and align the
+ * [*offset, *bytes] range to clusters if COW is needed.
  *
- * *op->bytes_handled is set to the number of bytes copied after and
+ * *bytes_handled is set to the number of bytes copied after and
  * including offset, excluding any bytes copied prior to offset due
- * to alignment.  This will be op->bytes if no alignment is necessary,
- * or (new_end - op->offset) if the tail is rounded up or down due to
+ * to alignment.  This will be *bytes if no alignment is necessary, or
+ * (new_end - *offset) if the tail is rounded up or down due to
  * alignment or buffer limit.
  */
-static void coroutine_fn mirror_co_read(void *opaque)
+static void mirror_align_for_copy(MirrorBlockJob *s,
+                                  int64_t *offset, uint64_t *bytes,
+                                  int64_t *bytes_handled)
 {
-    MirrorOp *op = opaque;
-    MirrorBlockJob *s = op->s;
-    int nb_chunks;
-    uint64_t ret;
     uint64_t max_bytes;
 
     max_bytes = s->granularity * s->max_iov;
 
     /* We can only handle as much as buf_size at a time. */
-    op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes));
-    assert(op->bytes);
-    assert(op->bytes < BDRV_REQUEST_MAX_BYTES);
-    *op->bytes_handled = op->bytes;
+    *bytes = MIN(s->buf_size, MIN(max_bytes, *bytes));
+    assert(*bytes);
+    assert(*bytes < BDRV_REQUEST_MAX_BYTES);
+    *bytes_handled = *bytes;
 
     if (s->cow_bitmap) {
-        *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes);
+        *bytes_handled += mirror_cow_align(s, offset, bytes);
     }
     /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */
-    assert(*op->bytes_handled <= UINT_MAX);
-    assert(op->bytes <= s->buf_size);
+    assert(*bytes_handled <= UINT_MAX);
+    assert(*bytes <= s->buf_size);
     /* The offset is granularity-aligned because:
      * 1) Caller passes in aligned values;
      * 2) mirror_cow_align is used only when target cluster is larger. */
-    assert(QEMU_IS_ALIGNED(op->offset, s->granularity));
+    assert(QEMU_IS_ALIGNED(*offset, s->granularity));
     /* The range is sector-aligned, since bdrv_getlength() rounds up. */
-    assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE));
+    assert(QEMU_IS_ALIGNED(*bytes, BDRV_SECTOR_SIZE));
+}
+
+/* Perform a mirror copy operation.
+ *
+ * *op->bytes_handled is set to the number of bytes copied after and
+ * including offset, excluding any bytes copied prior to offset due
+ * to alignment.  This will be op->bytes if no alignment is necessary,
+ * or (new_end - op->offset) if the tail is rounded up or down due to
+ * alignment or buffer limit.
+ */
+static void coroutine_fn mirror_co_read(void *opaque)
+{
+    MirrorOp *op = opaque;
+    MirrorBlockJob *s = op->s;
+    int nb_chunks;
+    uint64_t ret;
+
+    mirror_align_for_copy(s, &op->offset, &op->bytes, op->bytes_handled);
     nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity);
 
     while (s->buf_free_count < nb_chunks) {
-- 
2.17.1