[Cluster-devel] [PATCH] GFS2: Sort buffer lists by inplace block number

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

Now in the -nmw git tree. Thanks,

Steve.

On Tue, 2013-05-07 at 09:58 -0500, Benjamin Marzinski wrote:
> This patch simply sort the data and metadata buffer lists by their
> inplace block number.  This makes gfs2_log_flush issue the inplace IO
> in sequential order, which will hopefully speed up writing the IO
> out to disk.
> 
> Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
> ---
>  fs/gfs2/lops.c |   16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> Index: gfs2-3.0-nmw-130405/fs/gfs2/lops.c
> ===================================================================
> --- gfs2-3.0-nmw-130405.orig/fs/gfs2/lops.c
> +++ gfs2-3.0-nmw-130405/fs/gfs2/lops.c
> @@ -16,6 +16,7 @@
>  #include <linux/gfs2_ondisk.h>
>  #include <linux/bio.h>
>  #include <linux/fs.h>
> +#include <linux/list_sort.h>
>  
>  #include "gfs2.h"
>  #include "incore.h"
> @@ -401,6 +402,20 @@ static void gfs2_check_magic(struct buff
>  	kunmap_atomic(kaddr);
>  }
>  
> +static int blocknr_cmp(void *priv, struct list_head *a, struct list_head *b)
> +{
> +	struct gfs2_bufdata *bda, *bdb;
> +
> +	bda = list_entry(a, struct gfs2_bufdata, bd_list);
> +	bdb = list_entry(b, struct gfs2_bufdata, bd_list);
> +
> +	if (bda->bd_bh->b_blocknr < bdb->bd_bh->b_blocknr)
> +		return -1;
> +	if (bda->bd_bh->b_blocknr > bdb->bd_bh->b_blocknr)
> +		return 1;
> +	return 0;
> +}
> +
>  static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,
>  				unsigned int total, struct list_head *blist,
>  				bool is_databuf)
> @@ -413,6 +428,7 @@ static void gfs2_before_commit(struct gf
>  	__be64 *ptr;
>  
>  	gfs2_log_lock(sdp);
> +	list_sort(NULL, blist, blocknr_cmp);
>  	bd1 = bd2 = list_prepare_entry(bd1, blist, bd_list);
>  	while(total) {
>  		num = total;
>