From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bob Peterson Date: Wed, 11 Sep 2013 13:43:56 -0500 Subject: [Cluster-devel] [PATCH 1/5] GFS2: optimize rbm_from_block wrt bi_start Message-ID: <1378925045-23318-2-git-send-email-rpeterso@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit In function gfs2_rbm_from_block, it starts by checking if the block falls within the first bitmap. It does so by checking if the rbm's offset is less than (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY. However, the first bitmap will always have bi_start==0. Therefore this is an unnecessary calculation in a function that gets called billions of times. This patch removes the reference to bi_start. --- fs/gfs2/rgrp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c index 6931743..7a6fa03 100644 --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -262,7 +262,7 @@ static int gfs2_rbm_from_block(struct gfs2_rbm *rbm, u64 block) rbm->bi = rbm->rgd->rd_bits; rbm->offset = (u32)(rblock); /* Check if the block is within the first block */ - if (rbm->offset < (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY) + if (rbm->offset < rbm->bi->bi_len * GFS2_NBBY) return 0; /* Adjust for the size diff between gfs2_meta_header and gfs2_rgrp */ -- 1.8.3.1