From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Gruenbacher Date: Fri, 10 Aug 2018 14:13:51 +0200 Subject: [Cluster-devel] [GFS2 PATCH] GFS2: Simplify iterative add loop in foreach_descriptor In-Reply-To: <2e040139-cc86-3256-884e-8e52e48e6df7@redhat.com> References: <183182471.770089.1533754323408.JavaMail.zimbra@redhat.com> <2e040139-cc86-3256-884e-8e52e48e6df7@redhat.com> Message-ID: List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 9 August 2018 at 11:35, Steven Whitehouse wrote: > Hi, > > > > On 08/08/18 19:52, Bob Peterson wrote: >> >> Hi, >> >> Before this patch, function foreach_descriptor repeatedly called >> function gfs2_replay_incr_blk which just incremented the value while >> decrementing another, and checked for wrap. This is a waste of time. >> This patch just adds the value and adjusts it if a wrap occurred. >> >> Signed-off-by: Bob Peterson >> --- >> fs/gfs2/recovery.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/fs/gfs2/recovery.c b/fs/gfs2/recovery.c >> index 0f501f938d1c..6c6b19263b82 100644 >> --- a/fs/gfs2/recovery.c >> +++ b/fs/gfs2/recovery.c >> @@ -354,8 +354,9 @@ static int foreach_descriptor(struct gfs2_jdesc *jd, >> unsigned int start, >> return error; >> } >> - while (length--) >> - gfs2_replay_incr_blk(jd, &start); >> + start += length; >> + if (start >= jd->jd_blocks) >> + start -= jd->jd_blocks; >> brelse(bh); >> } >> > > Now you've hidden the increment of the replay block. Please don't open code > this, but just add an argument to gfs2_replay_incr_blk() such that you can > tell it how many blocks to increment, rather than just assuming a single > block as it does at the moment. Otherwise this can easily get missed when > someone looks at the code in future, and expects gfs2_replay_incr_blk to be > the only thing that changes the position during recovery, If we really want to encapsulate "add modulo jd->jd_blocks", it's also open-coded in find_good_lh and jhead_scan. Andreas