[Cluster-devel] [GFS2 PATCH] GFS2: Simplify iterative add loop in foreach_descriptor

[Steven Whitehouse <swhiteho@redhat.com>]

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 <rpeterso@redhat.com>
> ---
>   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,

Steve.