[Qemu-devel] [PATCH 04/21] backup: use copy_bitmap in incremental backup

[Vladimir Sementsov-Ogievskiy]

We can use copy_bitmap instead of sync_bitmap. copy_bitmap is
initialized from sync_bitmap and it is more informative: we will not try
to process data, that is already in progress (by write notifier).

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 block/backup.c | 58 +++++++++++++++++++---------------------------------------
 1 file changed, 19 insertions(+), 39 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index f1f87f6..938b7df 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -376,50 +376,30 @@ static bool coroutine_fn yield_and_check(BackupBlockJob 
*job)
 
 static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
 {
+    int ret;
     bool error_is_read;
-    int ret = 0;
-    int clusters_per_iter;
-    uint32_t granularity;
-    int64_t sector;
-    int64_t cluster;
-    int64_t end;
     int64_t sectors_per_cluster = cluster_size_sectors(job);
-    BdrvDirtyBitmapIter *dbi;
-
-    granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
-    clusters_per_iter = MAX((granularity / job->cluster_size), 1);
-    dbi = bdrv_dirty_iter_new(job->sync_bitmap, 0);
-
-    /* Find the next dirty sector(s) */
-    while ((sector = bdrv_dirty_iter_next(dbi)) != -1) {
-        cluster = sector / sectors_per_cluster;
-
-        for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
-            do {
-                if (yield_and_check(job)) {
-                    goto out;
-                }
-                ret = backup_do_cow(job, cluster * sectors_per_cluster,
-                                    sectors_per_cluster, &error_is_read,
-                                    false);
-                if ((ret < 0) &&
-                    backup_error_action(job, error_is_read, -ret) ==
-                    BLOCK_ERROR_ACTION_REPORT) {
-                    goto out;
-                }
-            } while (ret < 0);
-        }
+    int64_t cluster;
+    HBitmapIter hbi;
 
-        /* If the bitmap granularity is smaller than the backup granularity,
-         * we need to advance the iterator pointer to the next cluster. */
-        if (granularity < job->cluster_size) {
-            bdrv_set_dirty_iter(dbi, cluster * sectors_per_cluster);
-        }
+    hbitmap_iter_init(&hbi, job->copy_bitmap, 0);
+    while ((cluster = hbitmap_iter_next(&hbi)) != -1) {
+        do {
+            if (yield_and_check(job)) {
+                return 0;
+            }
+            ret = backup_do_cow(job, cluster * sectors_per_cluster,
+                                sectors_per_cluster, &error_is_read,
+                                false);
+            if ((ret < 0) &&
+                backup_error_action(job, error_is_read, -ret) ==
+                BLOCK_ERROR_ACTION_REPORT) {
+                return ret;
+            }
+        } while (ret < 0);
     }
 
-out:
-    bdrv_dirty_iter_free(dbi);
-    return ret;
+    return 0;
 }
 
 /* init copy_bitmap from sync_bitmap */
-- 
1.8.3.1