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-rw-r--r--fs/ocfs2/refcounttree.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 3ac5aa733e9c..73a11ccfd4c2 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2436,16 +2436,26 @@ static int ocfs2_calc_refcount_meta_credits(struct super_block *sb,
len = min((u64)cpos + clusters, le64_to_cpu(rec.r_cpos) +
le32_to_cpu(rec.r_clusters)) - cpos;
/*
- * If the refcount rec already exist, cool. We just need
- * to check whether there is a split. Otherwise we just need
- * to increase the refcount.
- * If we will insert one, increases recs_add.
- *
* We record all the records which will be inserted to the
* same refcount block, so that we can tell exactly whether
* we need a new refcount block or not.
+ *
+ * If we will insert a new one, this is easy and only happens
+ * during adding refcounted flag to the extent, so we don't
+ * have a chance of spliting. We just need one record.
+ *
+ * If the refcount rec already exists, that would be a little
+ * complicated. we may have to:
+ * 1) split at the beginning if the start pos isn't aligned.
+ * we need 1 more record in this case.
+ * 2) split int the end if the end pos isn't aligned.
+ * we need 1 more record in this case.
+ * 3) split in the middle because of file system fragmentation.
+ * we need 2 more records in this case(we can't detect this
+ * beforehand, so always think of the worst case).
*/
if (rec.r_refcount) {
+ recs_add += 2;
/* Check whether we need a split at the beginning. */
if (cpos == start_cpos &&
cpos != le64_to_cpu(rec.r_cpos))