GFS2: Sort the ordered write list

This patch sorts the ordered write list for GFS2 writes.
This increases the throughput for simultaneous writes.
For example, if you have ten processes, all doing:
dd if=/dev/zero of=/mnt/gfs2/fileX
on different files, the throughput will be much better.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 4d31379265cb8c97e0f6865c0fd0413921322ee9..b8fe7b739c278642e68e0cd9e66c75a3ecffe5a2 100644 (file)
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -19,6 +19,7 @@
 #include <linux/freezer.h>
 #include <linux/bio.h>
 #include <linux/writeback.h>
+#include <linux/list_sort.h>
 
 #include "gfs2.h"
 #include "incore.h"
@@ -566,6 +567,20 @@ static void log_flush_commit(struct gfs2_sbd *sdp)
        log_write_header(sdp, 0, 0);
 }
 
+int bd_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+       struct gfs2_bufdata *bda, *bdb;
+
+       bda = list_entry(a, struct gfs2_bufdata, bd_le.le_list);
+       bdb = list_entry(b, struct gfs2_bufdata, bd_le.le_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_ordered_write(struct gfs2_sbd *sdp)
 {
        struct gfs2_bufdata *bd;
@@ -573,6 +588,7 @@ static void gfs2_ordered_write(struct gfs2_sbd *sdp)
        LIST_HEAD(written);
 
        gfs2_log_lock(sdp);
+       list_sort(NULL, &sdp->sd_log_le_ordered, &bd_cmp);
        while (!list_empty(&sdp->sd_log_le_ordered)) {
                bd = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_bufdata, bd_le.le_list);
                list_move(&bd->bd_le.le_list, &written);