GFS2: Add readahead to sequential directory traversal

This patch adds read-ahead capability to GFS2's
directory hash table management.  It greatly improves
performance for some directory operations.  For example:
In one of my file systems that has 1000 directories, each
of which has 1000 files, time to execute a recursive
ls (time ls -fR /mnt/gfs2 > /dev/null) was reduced
from 2m2.814s on a stock kernel to 0m45.938s.

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

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/gfs2/export.c b/fs/gfs2/export.c
index fe9945f2ff72..70ba891654f8 100644
--- a/fs/gfs2/export.c
+++ b/fs/gfs2/export.c
@@ -99,6 +99,7 @@ static int gfs2_get_name(struct dentry *parent, char *name,
         struct gfs2_holder gh;
         u64 offset = 0;
         int error;
+        struct file_ra_state f_ra = { .start = 0 };
 
         if (!dir)
                 return -EINVAL;
@@ -118,7 +119,7 @@ static int gfs2_get_name(struct dentry *parent, char *name,
         if (error)
                 return error;
 
-        error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
+        error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir, &f_ra);
 
         gfs2_glock_dq_uninit(&gh);