From c7dd06b6bbf9e664c6e2de85124e6326b1b8e9e2 Mon Sep 17 00:00:00 2001
From: martin <martin@NetBSD.org>
Date: Sat, 7 Jun 2014 09:54:34 +0000
Subject: [PATCH] Remove the hardcoded 4 MB free kernel memory limit and
 replace it by uvmexp.freetarg, as discussed on tech-kern. Main purpose is to
 make tmpfs usable (as far as possible) on small memory machines. This is a
 bit experimental, but we need to give it some real world exposure to see how
 well it works.

---
 sys/fs/tmpfs/tmpfs.h        |  9 +--------
 sys/fs/tmpfs/tmpfs_mem.c    | 10 +++++-----
 sys/fs/tmpfs/tmpfs_vfsops.c |  6 +++---
 3 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/sys/fs/tmpfs/tmpfs.h b/sys/fs/tmpfs/tmpfs.h
index d4b90bf0e281..8625ffb44a20 100644
--- a/sys/fs/tmpfs/tmpfs.h
+++ b/sys/fs/tmpfs/tmpfs.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: tmpfs.h,v 1.49 2014/04/30 01:33:51 christos Exp $	*/
+/*	$NetBSD: tmpfs.h,v 1.50 2014/06/07 09:54:34 martin Exp $	*/
 
 /*
  * Copyright (c) 2005, 2006, 2007 The NetBSD Foundation, Inc.
@@ -306,13 +306,6 @@ bool		tmpfs_strname_neqlen(struct componentname *, struct componentname *);
     KASSERT((node)->tn_type == VDIR); \
     KASSERT((node)->tn_size % sizeof(tmpfs_dirent_t) == 0);
 
-/*
- * Memory management stuff.
- */
-
-/* Amount of memory pages to reserve for the system. */
-#define	TMPFS_PAGES_RESERVED	(4 * 1024 * 1024 / PAGE_SIZE)
-
 /*
  * Routines to convert VFS structures to tmpfs internal ones.
  */
diff --git a/sys/fs/tmpfs/tmpfs_mem.c b/sys/fs/tmpfs/tmpfs_mem.c
index 8f752410d661..0abf8123e5ca 100644
--- a/sys/fs/tmpfs/tmpfs_mem.c
+++ b/sys/fs/tmpfs/tmpfs_mem.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: tmpfs_mem.c,v 1.5 2014/04/30 01:33:51 christos Exp $	*/
+/*	$NetBSD: tmpfs_mem.c,v 1.6 2014/06/07 09:54:34 martin Exp $	*/
 
 /*
  * Copyright (c) 2010, 2011 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tmpfs_mem.c,v 1.5 2014/04/30 01:33:51 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tmpfs_mem.c,v 1.6 2014/06/07 09:54:34 martin Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -89,7 +89,7 @@ tmpfs_mntmem_set(struct tmpfs_mount *mp, uint64_t memlimit)
  * => If 'total' is true, then return _total_ amount of pages.
  * => If false, then return the amount of _free_ memory pages.
  *
- * Remember to remove TMPFS_PAGES_RESERVED from the returned value to avoid
+ * Remember to remove uvmexp.freetarg from the returned value to avoid
  * excessive memory usage.
  */
 size_t
@@ -118,10 +118,10 @@ tmpfs_bytes_max(struct tmpfs_mount *mp)
 	size_t freepages = tmpfs_mem_info(false);
 	uint64_t avail_mem;
 
-	if (freepages < TMPFS_PAGES_RESERVED) {
+	if (freepages < uvmexp.freetarg) {
 		freepages = 0;
 	} else {
-		freepages -= TMPFS_PAGES_RESERVED;
+		freepages -= uvmexp.freetarg;
 	}
 	avail_mem = round_page(mp->tm_bytes_used) + (freepages << PAGE_SHIFT);
 	return MIN(mp->tm_mem_limit, avail_mem);
diff --git a/sys/fs/tmpfs/tmpfs_vfsops.c b/sys/fs/tmpfs/tmpfs_vfsops.c
index 35f7ede27751..ba412b55787c 100644
--- a/sys/fs/tmpfs/tmpfs_vfsops.c
+++ b/sys/fs/tmpfs/tmpfs_vfsops.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: tmpfs_vfsops.c,v 1.61 2014/04/30 01:59:30 christos Exp $	*/
+/*	$NetBSD: tmpfs_vfsops.c,v 1.62 2014/06/07 09:54:34 martin Exp $	*/
 
 /*
  * Copyright (c) 2005, 2006, 2007 The NetBSD Foundation, Inc.
@@ -42,7 +42,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tmpfs_vfsops.c,v 1.61 2014/04/30 01:59:30 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tmpfs_vfsops.c,v 1.62 2014/06/07 09:54:34 martin Exp $");
 
 #include <sys/param.h>
 #include <sys/types.h>
@@ -132,7 +132,7 @@ tmpfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
 
 
 	/* Prohibit mounts if there is not enough memory. */
-	if (tmpfs_mem_info(true) < TMPFS_PAGES_RESERVED)
+	if (tmpfs_mem_info(true) < uvmexp.freetarg)
 		return EINVAL;
 
 	/* Get the memory usage limit for this file-system. */