commit: Remove unused bytes_written

The bytes_written variable is only ever written to, it serves no
purpose. This has actually been the case since the commit job was first
introduced in commit 747ff60263.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200214200812.28180-3-kwolf@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/commit.c

@@ -140,7 +140,6 @@ static int coroutine_fn commit_run(Job *job, Error **errp)
     int ret = 0;
     int64_t n = 0; /* bytes */
     void *buf = NULL;
-    int bytes_written = 0;
     int64_t len, base_len;
 
     ret = len = blk_getlength(s->top);
@@ -180,7 +179,6 @@ static int coroutine_fn commit_run(Job *job, Error **errp)
         trace_commit_one_iteration(s, offset, n, ret);
         if (copy) {
             ret = commit_populate(s->top, s->base, offset, n, buf);
-            bytes_written += n;
         }
         if (ret < 0) {
             BlockErrorAction action =