[PATCH v5 04/22] parallels: Limit search in parallels_mark_used to the last marked claster

[Alexander Ivanov]

There is no necessity to search to the end of the bitmap. Limit the search
area as cluster_index + count.

Add cluster_end variable to avoid its calculation in a few places.

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
---
 block/parallels.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/block/parallels.c b/block/parallels.c
index ae524f1820..4470519656 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -182,13 +182,14 @@ int parallels_mark_used(BlockDriverState *bs, unsigned 
long *bitmap,
                         uint32_t bitmap_size, int64_t off, uint32_t count)
 {
     BDRVParallelsState *s = bs->opaque;
-    uint32_t cluster_index = host_cluster_index(s, off);
+    uint32_t cluster_end, cluster_index = host_cluster_index(s, off);
     unsigned long next_used;
-    if (cluster_index + count > bitmap_size) {
+    cluster_end = cluster_index + count;
+    if (cluster_end > bitmap_size) {
         return -E2BIG;
     }
-    next_used = find_next_bit(bitmap, bitmap_size, cluster_index);
-    if (next_used < cluster_index + count) {
+    next_used = find_next_bit(bitmap, cluster_end, cluster_index);
+    if (next_used < cluster_end) {
         return -EBUSY;
     }
     bitmap_set(bitmap, cluster_index, count);
-- 
2.40.1