[src/trunk]: src/sys/kern Add "FSTRANS=LOCK" and "FSTRANS=UNLOCK" to vop_lock...

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

details:   https://anonhg.NetBSD.org/src/rev/074316e46302
branches:  trunk
changeset: 354103:074316e46302
user:      hannken <hannken%NetBSD.org@localhost>
date:      Sun Jun 04 07:59:17 2017 +0000

description:
Add "FSTRANS=LOCK" and "FSTRANS=UNLOCK" to vop_lock and vop_unlock.

Add two "static inline" functions to vnode_if.c to handle MPSAFE
and FSTRANS before and after the "VCALL()".

Take FSTRANS and handle error before "VCALL(...vop_lock...)" and
release it after "VCALL(...vop_unlock...)".

diffstat:

 sys/kern/vnode_if.sh  |  100 +++++++++++++++++++++++++++++++++++++++++---------
 sys/kern/vnode_if.src |    6 +-
 2 files changed, 85 insertions(+), 21 deletions(-)

diffs (181 lines):

diff -r 20d87ef21025 -r 074316e46302 sys/kern/vnode_if.sh
--- a/sys/kern/vnode_if.sh      Sun Jun 04 07:58:29 2017 +0000
+++ b/sys/kern/vnode_if.sh      Sun Jun 04 07:59:17 2017 +0000
@@ -29,7 +29,7 @@
  * SUCH DAMAGE.
  */
 "
-SCRIPT_ID='$NetBSD: vnode_if.sh,v 1.64 2017/04/16 17:18:28 riastradh Exp $'
+SCRIPT_ID='$NetBSD: vnode_if.sh,v 1.65 2017/06/04 07:59:17 hannken Exp $'
 
 # Script to produce VFS front-end sugar.
 #
@@ -100,7 +100,7 @@
        args_name=$1;
        argc=0;
        willmake=-1;
-       fstrans=0;
+       fstrans="";
        next;
 }
 # Last line of description
@@ -113,11 +113,9 @@
        if ($1 == "VERSION") {
                args_name=args_name "_v" $2;
                next;
-       } else if ($1 == "FSTRANS=YES") {
-               fstrans = 1;
-               next;
-       } else if ($1 == "FSTRANS=NO") {
-               fstrans = -1;
+       } else if ($1 ~ "^FSTRANS=") {
+               fstrans = $1;
+               sub("FSTRANS=", "", fstrans);
                next;
        }
 
@@ -147,8 +145,12 @@
                willmake=argc;
                i++;
        }
-       if (argc == 0 && fstrans == 0 && lockstate[0] != 1)
-               fstrans = 1;
+       if (argc == 0 && fstrans == "") {
+               if (lockstate[0] == 1)
+                       fstrans = "NO";
+               else
+                       fstrans = "YES";
+       }
 
        # XXX: replace non-portable types for rump.  We should really
        # nuke the types from the kernel, but that is a battle for
@@ -316,6 +318,57 @@
 
 if [ -z "${rump}" ] ; then
        echo "
+enum fst_op { FST_NO, FST_YES, FST_TRY };
+
+static inline int
+vop_pre(vnode_t *vp, struct mount **mp, bool *mpsafe, enum fst_op op)
+{
+       int error;
+
+       *mpsafe = (vp->v_vflag & VV_MPSAFE);
+
+       if (!*mpsafe) {
+               KERNEL_LOCK(1, curlwp);
+       }
+
+       if (op == FST_YES || op == FST_TRY) {
+               for (;;) {
+                       *mp = vp->v_mount;
+                       if (op == FST_TRY) {
+                               error = fstrans_start_nowait(*mp, FSTRANS_SHARED);
+                               if (error) {
+                                       if (!*mpsafe) {
+                                               KERNEL_UNLOCK_ONE(curlwp);
+                                       }
+                                       return error;
+                               }
+                       } else {
+                               fstrans_start(*mp, FSTRANS_SHARED);
+                       }
+                       if (__predict_true(*mp == vp->v_mount))
+                               break;
+                       fstrans_done(*mp);
+               }
+       } else {
+               *mp = vp->v_mount;
+       }
+
+       return 0;
+}
+
+static inline void
+vop_post(vnode_t *vp, struct mount *mp, bool mpsafe, enum fst_op op)
+{
+
+       if (op == FST_YES) {
+               fstrans_done(mp);
+       }
+
+       if (!mpsafe) {
+               KERNEL_UNLOCK_ONE(curlwp);
+       }
+}
+
 const struct vnodeop_desc vop_default_desc = {"
 echo ' 0,
        "default",
@@ -402,8 +455,7 @@
 function bodynorm() {
        printf("{\n\tint error;\n\tbool mpsafe;\n\tstruct %s_args a;\n",
                args_name);
-       if (fstrans == 1)
-               printf("\tstruct mount *mp = %s->v_mount;\n", argname[0]);
+       printf("\tstruct mount *mp;\n");
        if (lockdebug) {
                printf("#ifdef VNODE_LOCKDEBUG\n");
                for (i=0; i<argc; i++) {
@@ -425,15 +477,27 @@
                        printf("#endif\n");
                }
        }
-       printf("\tmpsafe = (%s->v_vflag & VV_MPSAFE);\n", argname[0]);
-       printf("\tif (!mpsafe) { KERNEL_LOCK(1, curlwp); }\n");
-       if (fstrans == 1)
-               printf("\tfstrans_start(mp, FSTRANS_SHARED);\n");
+       if (fstrans == "LOCK")
+               printf("\terror = vop_pre(%s, &mp, &mpsafe, %s);\n",
+                       argname[0], "(flags & LK_NOWAIT ? FST_TRY : FST_YES)");
+       else if (fstrans == "UNLOCK")
+               printf("\terror = vop_pre(%s, &mp, &mpsafe, FST_%s);\n",
+                       argname[0], "NO");
+       else
+               printf("\terror = vop_pre(%s, &mp, &mpsafe, FST_%s);\n",
+                       argname[0], fstrans);
+       printf("\tif (error)\n\t\treturn error;\n");
        printf("\terror = (VCALL(%s, VOFFSET(%s), &a));\n",
                argname[0], name);
-       if (fstrans == 1)
-               printf("\tfstrans_done(mp);\n");
-       printf("\tif (!mpsafe) { KERNEL_UNLOCK_ONE(curlwp); }\n");
+       if (fstrans == "LOCK")
+               printf("\tvop_post(%s, mp, mpsafe, %s);\n",
+                       argname[0], "(error ? FST_YES : FST_NO)");
+       else if (fstrans == "UNLOCK")
+               printf("\tvop_post(%s, mp, mpsafe, FST_%s);\n",
+                       argname[0], "YES");
+       else
+               printf("\tvop_post(%s, mp, mpsafe, FST_%s);\n",
+                       argname[0], fstrans);
        if (willmake != -1) {
                printf("#ifdef DIAGNOSTIC\n");
                printf("\tif (error == 0)\n"                            \
diff -r 20d87ef21025 -r 074316e46302 sys/kern/vnode_if.src
--- a/sys/kern/vnode_if.src     Sun Jun 04 07:58:29 2017 +0000
+++ b/sys/kern/vnode_if.src     Sun Jun 04 07:59:17 2017 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: vnode_if.src,v 1.75 2017/05/26 14:21:00 riastradh Exp $
+#      $NetBSD: vnode_if.src,v 1.76 2017/06/04 07:59:17 hannken Exp $
 #
 # Copyright (c) 1992, 1993
 #      The Regents of the University of California.  All rights reserved.
@@ -407,7 +407,7 @@
 #% lock               vp      U L U
 #
 vop_lock {
-       FSTRANS=NO
+       FSTRANS=LOCK
        IN LOCKED=NO struct vnode *vp;
        IN int flags;
 };
@@ -416,7 +416,7 @@
 #% unlock     vp      L U L
 #
 vop_unlock {
-       FSTRANS=NO
+       FSTRANS=UNLOCK
        IN LOCKED=YES struct vnode *vp;
 };