Re: [PATCH v4 04/21] parallels: Limit search in parallels_mark_used to the last marked claster

[Denis V. Lunev]

On 12/28/23 11:12, Alexander Ivanov wrote:

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 
---
  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);

Reviewed-by: Denis V. Lunev 

[PATCH v4 04/21] 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 
---
 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