[PATCH v4 05/21] parallels: Add parallels_mark_unused() helper

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

Add a helper to set unused areas in the used bitmap.

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

diff --git a/block/parallels.c b/block/parallels.c
index 4470519656..13726fb3d5 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -196,6 +196,24 @@ int parallels_mark_used(BlockDriverState *bs, unsigned long *bitmap,
     return 0;
 }
 
+int parallels_mark_unused(BlockDriverState *bs, unsigned long *bitmap,
+                          uint32_t bitmap_size, int64_t off, uint32_t count)
+{
+    BDRVParallelsState *s = bs->opaque;
+    uint32_t cluster_end, cluster_index = host_cluster_index(s, off);
+    unsigned long next_unused;
+    cluster_end = cluster_index + count;
+    if (cluster_end > bitmap_size) {
+        return -E2BIG;
+    }
+    next_unused = find_next_zero_bit(bitmap, cluster_end, cluster_index);
+    if (next_unused < cluster_end) {
+        return -EINVAL;
+    }
+    bitmap_clear(bitmap, cluster_index, count);
+    return 0;
+}
+
 /*
  * Collect used bitmap. The image can contain errors, we should fill the
  * bitmap anyway, as much as we can. This information will be used for
diff --git a/block/parallels.h b/block/parallels.h
index 68077416b1..02b857b4a4 100644
--- a/block/parallels.h
+++ b/block/parallels.h
@@ -92,6 +92,8 @@ typedef struct BDRVParallelsState {
 
 int parallels_mark_used(BlockDriverState *bs, unsigned long *bitmap,
                         uint32_t bitmap_size, int64_t off, uint32_t count);
+int parallels_mark_unused(BlockDriverState *bs, unsigned long *bitmap,
+                          uint32_t bitmap_size, int64_t off, uint32_t count);
 
 int GRAPH_RDLOCK
 parallels_read_format_extension(BlockDriverState *bs, int64_t ext_off,
-- 
2.40.1