block/block-copy: Simplify block_copy_do_copy()

block_copy_do_copy() is static, only used in block_copy_task_entry
with the error_is_read argument set. No need to check for it,
simplify.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200507121129.29760-3-philmd@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/block-copy.c

@@ -343,9 +343,7 @@ static int coroutine_fn block_copy_do_copy(BlockCopyState *s,
                                     ~BDRV_REQ_WRITE_COMPRESSED);
         if (ret < 0) {
             trace_block_copy_write_zeroes_fail(s, offset, ret);
-            if (error_is_read) {
-                *error_is_read = false;
-            }
+            *error_is_read = false;
         }
         return ret;
     }
@@ -393,19 +391,15 @@ static int coroutine_fn block_copy_do_copy(BlockCopyState *s,
     ret = bdrv_co_pread(s->source, offset, nbytes, bounce_buffer, 0);
     if (ret < 0) {
         trace_block_copy_read_fail(s, offset, ret);
-        if (error_is_read) {
-            *error_is_read = true;
-        }
+        *error_is_read = true;
         goto out;
     }
 
     ret = bdrv_co_pwrite(s->target, offset, nbytes, bounce_buffer,
                          s->write_flags);
     if (ret < 0) {
         trace_block_copy_write_fail(s, offset, ret);
-        if (error_is_read) {
-            *error_is_read = false;
-        }
+        *error_is_read = false;
         goto out;
     }