commit cf79cdf662aad365b53fc955f45fd47d9883c8df
author Eric Blake <eblake@redhat.com> Fri Jul 07 07:44:53 2017 -0500
committer Kevin Wolf <kwolf@redhat.com> Mon Jul 10 13:18:06 2017 +0200
tree b9cb81348abe06ec9685f6f130dfcd1a183fb24e
parent e8a81e9cadd0ec0e2cf3f564ae73809b0d8780da

backup: Switch BackupBlockJob to byte-based

We are gradually converting to byte-based interfaces, as they are
easier to reason about than sector-based.  Continue by converting an
internal structure (no semantic change), and all references to
tracking progress.  Drop a redundant local variable bytes_per_cluster.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/backup.c

diff --git a/block/backup.c b/block/backup.c
index 06431ac..4e64710 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -39,7 +39,7 @@
     BlockdevOnError on_source_error;
     BlockdevOnError on_target_error;
     CoRwlock flush_rwlock;
-    uint64_t sectors_read;
+    uint64_t bytes_read;
     unsigned long *done_bitmap;
     int64_t cluster_size;
     bool compress;
@@ -102,16 +102,15 @@
     void *bounce_buffer = NULL;
     int ret = 0;
     int64_t sectors_per_cluster = cluster_size_sectors(job);
-    int64_t bytes_per_cluster = sectors_per_cluster * BDRV_SECTOR_SIZE;
-    int64_t start, end;
-    int n;
+    int64_t start, end; /* clusters */
+    int n; /* bytes */
 
     qemu_co_rwlock_rdlock(&job->flush_rwlock);
 
     start = sector_num / sectors_per_cluster;
     end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster);
 
-    trace_backup_do_cow_enter(job, start * bytes_per_cluster,
+    trace_backup_do_cow_enter(job, start * job->cluster_size,
                               sector_num * BDRV_SECTOR_SIZE,
                               nb_sectors * BDRV_SECTOR_SIZE);
 
@@ -120,28 +119,27 @@
 
     for (; start < end; start++) {
         if (test_bit(start, job->done_bitmap)) {
-            trace_backup_do_cow_skip(job, start * bytes_per_cluster);
+            trace_backup_do_cow_skip(job, start * job->cluster_size);
             continue; /* already copied */
         }
 
-        trace_backup_do_cow_process(job, start * bytes_per_cluster);
+        trace_backup_do_cow_process(job, start * job->cluster_size);
 
-        n = MIN(sectors_per_cluster,
-                job->common.len / BDRV_SECTOR_SIZE -
-                start * sectors_per_cluster);
+        n = MIN(job->cluster_size,
+                job->common.len - start * job->cluster_size);
 
         if (!bounce_buffer) {
             bounce_buffer = blk_blockalign(blk, job->cluster_size);
         }
         iov.iov_base = bounce_buffer;
-        iov.iov_len = n * BDRV_SECTOR_SIZE;
+        iov.iov_len = n;
         qemu_iovec_init_external(&bounce_qiov, &iov, 1);
 
         ret = blk_co_preadv(blk, start * job->cluster_size,
                             bounce_qiov.size, &bounce_qiov,
                             is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0);
         if (ret < 0) {
-            trace_backup_do_cow_read_fail(job, start * bytes_per_cluster, ret);
+            trace_backup_do_cow_read_fail(job, start * job->cluster_size, ret);
             if (error_is_read) {
                 *error_is_read = true;
             }
@@ -157,7 +155,7 @@
                                  job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0);
         }
         if (ret < 0) {
-            trace_backup_do_cow_write_fail(job, start * bytes_per_cluster, ret);
+            trace_backup_do_cow_write_fail(job, start * job->cluster_size, ret);
             if (error_is_read) {
                 *error_is_read = false;
             }
@@ -169,8 +167,8 @@
         /* Publish progress, guest I/O counts as progress too.  Note that the
          * offset field is an opaque progress value, it is not a disk offset.
          */
-        job->sectors_read += n;
-        job->common.offset += n * BDRV_SECTOR_SIZE;
+        job->bytes_read += n;
+        job->common.offset += n;
     }
 
 out:
@@ -363,9 +361,8 @@
      */
     if (job->common.speed) {
         uint64_t delay_ns = ratelimit_calculate_delay(&job->limit,
-                                                      job->sectors_read *
-                                                      BDRV_SECTOR_SIZE);
-        job->sectors_read = 0;
+                                                      job->bytes_read);
+        job->bytes_read = 0;
         block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
     } else {
         block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);