GFS2: Kill two daemons with one patch

This patch removes the two daemons, gfs2_scand and gfs2_glockd
and replaces them with a shrinker which is called from the VM.

The net result is that GFS2 responds better when there is memory
pressure, since it shrinks the glock cache at the same rate
as the VFS shrinks the dcache and icache. There are no longer
any time based criteria for shrinking glocks, they are kept
until such time as the VM asks for more memory and then we
demote just as many glocks as required.

There are potential future changes to this code, including the
possibility of sorting the glocks which are to be written back
into inode number order, to get a better I/O ordering. It would
be very useful to have an elevator based workqueue implementation
for this, as that would automatically deal with the read I/O cases
at the same time.

This patch is my answer to Andrew Morton's remark, made during
the initial review of GFS2, asking why GFS2 needs so many kernel
threads, the answer being that it doesn't :-) This patch is a
net loss of about 200 lines of code.

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

1 files changed, 0 insertions, 61 deletions

diff --git a/fs/gfs2/daemon.c b/fs/gfs2/daemon.c
deleted file mode 100644
index 2662df0d5b93..000000000000
--- a/fs/gfs2/daemon.c
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
- * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
- *
- * This copyrighted material is made available to anyone wishing to use,
- * modify, copy, or redistribute it subject to the terms and conditions
- * of the GNU General Public License version 2.
- */
-
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/completion.h>
-#include <linux/buffer_head.h>
-#include <linux/kthread.h>
-#include <linux/delay.h>
-#include <linux/gfs2_ondisk.h>
-#include <linux/lm_interface.h>
-#include <linux/freezer.h>
-
-#include "gfs2.h"
-#include "incore.h"
-#include "daemon.h"
-#include "glock.h"
-#include "log.h"
-#include "recovery.h"
-#include "super.h"
-#include "util.h"
-
-/* This uses schedule_timeout() instead of msleep() because it's good for
-   the daemons to wake up more often than the timeout when unmounting so
-   the user's unmount doesn't sit there forever.
-
-   The kthread functions used to start these daemons block and flush signals. */
-
-/**
- * gfs2_glockd - Reclaim unused glock structures
- * @sdp: Pointer to GFS2 superblock
- *
- * One or more of these daemons run, reclaiming glocks on sd_reclaim_list.
- * Number of daemons can be set by user, with num_glockd mount option.
- */
-
-int gfs2_glockd(void *data)
-{
-	struct gfs2_sbd *sdp = data;
-
-	while (!kthread_should_stop()) {
-		while (atomic_read(&sdp->sd_reclaim_count))
-			gfs2_reclaim_glock(sdp);
-
-		wait_event_interruptible(sdp->sd_reclaim_wq,
-					 (atomic_read(&sdp->sd_reclaim_count) ||
-					 kthread_should_stop()));
-		if (freezing(current))
-			refrigerator();
-	}
-
-	return 0;
-}
-