[src/trunk]: src/sys/uvm When preparing to swap to a miniroot partition, add ...

[fredette <fredette%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a5757ff50028
branches:  trunk
changeset: 526766:a5757ff50028
user:      fredette <fredette%NetBSD.org@localhost>
date:      Thu May 09 21:43:44 2002 +0000

description:
When preparing to swap to a miniroot partition, add a little
padding to our estimate of the miniroot's size, to avoid
overwriting it.

diffstat:

 sys/uvm/uvm_swap.c |  18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diffs (39 lines):

diff -r 57f350d44d77 -r a5757ff50028 sys/uvm/uvm_swap.c
--- a/sys/uvm/uvm_swap.c        Thu May 09 20:32:59 2002 +0000
+++ b/sys/uvm/uvm_swap.c        Thu May 09 21:43:44 2002 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_swap.c,v 1.63 2002/04/01 12:24:11 manu Exp $       */
+/*     $NetBSD: uvm_swap.c,v 1.64 2002/05/09 21:43:44 fredette Exp $   */
 
 /*
  * Copyright (c) 1995, 1996, 1997 Matthew R. Green
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_swap.c,v 1.63 2002/04/01 12:24:11 manu Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_swap.c,v 1.64 2002/05/09 21:43:44 fredette Exp $");
 
 #include "fs_nfs.h"
 #include "opt_uvmhist.h"
@@ -906,6 +906,20 @@
                mp = rootvnode->v_mount;
                sp = &mp->mnt_stat;
                rootblocks = sp->f_blocks * btodb(sp->f_bsize);
+               /*
+                * XXX: sp->f_blocks isn't the total number of
+                * blocks in the filesystem, it's the number of
+                * data blocks.  so, our rootblocks almost
+                * definitely underestimates the total size 
+                * of the filesystem - how badly depends on the
+                * details of the filesystem type.  there isn't 
+                * an obvious way to deal with this cleanly
+                * and perfectly, so for now we just pad our 
+                * rootblocks estimate with an extra 5 percent.
+                */
+               rootblocks += (rootblocks >> 5) +
+                       (rootblocks >> 6) +
+                       (rootblocks >> 7);
                rootpages = round_page(dbtob(rootblocks)) >> PAGE_SHIFT;
                if (rootpages > size)
                        panic("swap_on: miniroot larger than swap?");