From 8a2e70c40ff58f82dde67770e6623ca45f0cb0c8 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Thu, 22 Jul 2010 13:56:45 +0800 Subject: ocfs2: Count more refcount records in file system fragmentation. The refcount record calculation in ocfs2_calc_refcount_meta_credits is too optimistic that we can always allocate contiguous clusters and handle an already existed refcount rec as a whole. Actually because of file system fragmentation, we may have the chance to split a refcount record into 3 parts during the transaction. So consider the worst case in record calculation. Cc: stable@kernel.org Signed-off-by: Tao Ma Signed-off-by: Joel Becker --- fs/ocfs2/refcounttree.c | 20 +++++++++++++++----- 1 file 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)) -- cgit v1.2.3