[PATCH v3 16/21] parallels: Truncate images on the last used cluster

[Alexander Ivanov <alexander.ivanov@virtuozzo.com>]

On an image closing there can be unused clusters in the end of the image.
Truncate these clusters and update data_end field.

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
 block/parallels.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/block/parallels.c b/block/parallels.c
index 354fa0f2cc..472311e2e6 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -1456,6 +1456,23 @@ fail:
     return ret;
 }
 
+static int parallels_truncate_unused_clusters(BlockDriverState *bs)
+{
+    BDRVParallelsState *s = bs->opaque;
+    uint64_t end_off = 0;
+    if (s->used_bmap_size > 0) {
+        end_off = find_last_bit(s->used_bmap, s->used_bmap_size);
+        if (end_off == s->used_bmap_size) {
+            end_off = 0;
+        } else {
+            end_off = (end_off + 1) * s->cluster_size;
+        }
+    }
+    end_off += s->data_start * BDRV_SECTOR_SIZE;
+    s->data_end = end_off / BDRV_SECTOR_SIZE;
+    return bdrv_truncate(bs->file, end_off, true, PREALLOC_MODE_OFF, 0, NULL);
+}
+
 static int GRAPH_RDLOCK parallels_inactivate(BlockDriverState *bs)
 {
     BDRVParallelsState *s = bs->opaque;
@@ -1473,8 +1490,7 @@ static int GRAPH_RDLOCK parallels_inactivate(BlockDriverState *bs)
     parallels_update_header(bs);
 
     /* errors are ignored, so we might as well pass exact=true */
-    ret = bdrv_truncate(bs->file, s->data_end << BDRV_SECTOR_BITS,
-                        true, PREALLOC_MODE_OFF, 0, NULL);
+    ret = parallels_truncate_unused_clusters(bs);
     if (ret < 0) {
         error_report("Failed to truncate image: %s", strerror(-ret));
     }
-- 
2.34.1