[src/trunk]: src/lib/libp2k Don't VOP_PUTPAGES(PGO_FREE) in inactive for tmpf...

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

details:   https://anonhg.NetBSD.org/src/rev/7887a3d07e11
branches:  trunk
changeset: 750098:7887a3d07e11
user:      pooka <pooka%NetBSD.org@localhost>
date:      Wed Dec 16 17:20:19 2009 +0000

description:
Don't VOP_PUTPAGES(PGO_FREE) in inactive for tmpfs, since we now
(after some changes to rump) actually free those pages, leaving
the tmpfs vnode feeling quite empty.
(the purpose of the flush is to avoid double caching between the
rump kernel and puffs vfs layer)

diffstat:

 lib/libp2k/p2k.c |  27 +++++++++++++++++++++++----
 1 files changed, 23 insertions(+), 4 deletions(-)

diffs (63 lines):

diff -r af4772799ec8 -r 7887a3d07e11 lib/libp2k/p2k.c
--- a/lib/libp2k/p2k.c  Wed Dec 16 16:50:49 2009 +0000
+++ b/lib/libp2k/p2k.c  Wed Dec 16 17:20:19 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: p2k.c,v 1.30 2009/12/03 14:27:16 pooka Exp $   */
+/*     $NetBSD: p2k.c,v 1.31 2009/12/16 17:20:19 pooka Exp $   */
 
 /*
  * Copyright (c) 2007, 2008, 2009  Antti Kantee.  All Rights Reserved.
@@ -72,6 +72,7 @@
        struct ukfs *p2m_ukfs;
        struct p2k_vp_hash p2m_vphash[NHASHBUCK];
        int p2m_nvnodes;
+       int p2m_imtmpfsman;
 };
 
 struct p2k_node {
@@ -404,6 +405,16 @@
        p2m->p2m_ukfs = ukfs;
        p2m->p2m_pu = pu;
 
+       /*
+        * Detect tmpfs.  XXX: this is a kludge.  See inactive().
+        *
+        * In reality we'd want "does file system use anon objects
+        * for storage?".  But since tmpfs hides the anon object from
+        * the public interface, we can't actually detect it sanely.
+        * Therefore, use this kludge.
+        */
+       p2m->p2m_imtmpfsman = strcmp(vfsname, MOUNT_TMPFS) == 0;
+
        p2m->p2m_rvp = ukfs_getrvp(ukfs);
        p2n_root = getp2n(p2m, p2m->p2m_rvp, true, NULL);
        puffs_setfhsize(pu, 0, PUFFS_FHFLAG_PASSTHROUGH);
@@ -1217,6 +1228,8 @@
 int
 p2k_node_inactive(struct puffs_usermount *pu, puffs_cookie_t opc)
 {
+       struct ukfs *fs = puffs_getspecific(pu);
+       struct p2k_mount *p2m = ukfs_getspecific(fs);
        struct p2k_node *p2n = opc;
        struct vnode *vp = OPC2VP(opc);
        bool recycle = false;
@@ -1228,10 +1241,16 @@
 
        /*
         * Flush all cached vnode pages from the rump kernel -- they
-        * are kept in puffs for all things that matter.
+        * are kept in puffs for all things that matter.  However,
+        * don't do this for tmpfs (vnodes are backed by an aobj), since that
+        * would cause us to clear the backing storage leaving us without
+        * a way to regain the data from "stable storage".
         */
-       rump_pub_vp_interlock(vp);
-       (void) RUMP_VOP_PUTPAGES(vp, 0, 0, PGO_ALLPAGES|PGO_CLEANIT|PGO_FREE);
+       if (!p2m->p2m_imtmpfsman) {
+               rump_pub_vp_interlock(vp);
+               RUMP_VOP_PUTPAGES(vp, 0, 0,
+                   PGO_ALLPAGES|PGO_CLEANIT|PGO_FREE);
+       }
 
        /*
         * Ok, this is where we get nasty.  We pretend the vnode is