Use memcmp for check sample data to zeroes.
Signed-off-by: Timofey Titovets <nefelim4ag@xxxxxxxxx>
---
fs/btrfs/heuristic.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/fs/btrfs/heuristic.c b/fs/btrfs/heuristic.c
index 5336638a3b7c..4557ea1db373 100644
--- a/fs/btrfs/heuristic.c
+++ b/fs/btrfs/heuristic.c
@@ -73,6 +73,21 @@ static struct list_head *heuristic_alloc_workspace(void)
return ERR_PTR(-ENOMEM);
}
+static bool sample_zeroed(struct workspace *workspace)
+{
+ u32 i;
+ u8 zero[READ_SIZE];
+
+ memset(&zero, 0, sizeof(zero));
+
+ for (i = 0; i < workspace->sample_size; i += sizeof(zero)) {
+ if (memcmp(&workspace->sample[i], &zero, sizeof(zero)))
+ return false;
+ }
+
+ return true;
+}
+
static int heuristic(struct list_head *ws, struct inode *inode,
u64 start, u64 end)
{
@@ -110,6 +125,9 @@ static int heuristic(struct list_head *ws, struct inode *inode,
workspace->sample_size = b;
+ if (sample_zeroed(workspace))
+ return 1;
+
memset(workspace->bucket, 0, sizeof(*workspace->bucket)*BUCKET_SIZE);
for (a = 0; a < workspace->sample_size; a++) {
--
2.14.1
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