GFS2: Use filemap_fdatawrite() to write back the AIL

In order to ensure that the mapping stats (and thus the bdi) are correctly
updated, this patch changes the AIL writeback to use the filemap_datawrite
function. This helps prevent stalls in balance_dirty_pages() due to
large amounts of dirty metadata when there is little or no dirty data
around.

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

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 5b102c1..3ebafa1 100644 (file)
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -91,6 +91,7 @@ static void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
 __releases(&sdp->sd_ail_lock)
 __acquires(&sdp->sd_ail_lock)
 {
+       struct gfs2_glock *gl = NULL;
        struct gfs2_bufdata *bd, *s;
        struct buffer_head *bh;
        int retry;
@@ -113,19 +114,13 @@ __acquires(&sdp->sd_ail_lock)
 
                        if (!buffer_dirty(bh))
                                continue;
-
+                       if (gl == bd->bd_gl)
+                               continue;
+                       gl = bd->bd_gl;
                        list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);
 
-                       get_bh(bh);
                        spin_unlock(&sdp->sd_ail_lock);
-                       lock_buffer(bh);
-                       if (test_clear_buffer_dirty(bh)) {
-                               bh->b_end_io = end_buffer_write_sync;
-                               submit_bh(WRITE_SYNC, bh);
-                       } else {
-                               unlock_buffer(bh);
-                               brelse(bh);
-                       }
+                       filemap_fdatawrite(gfs2_glock2aspace(gl));
                        spin_lock(&sdp->sd_ail_lock);
 
                        retry = 1;