[src/ad-namecache]: src/sys/miscfs/genfs Make sure LK_UPGRADE always comes wi...

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

details:   https://anonhg.NetBSD.org/src/rev/6d48c538a5b9
branches:  ad-namecache
changeset: 983001:6d48c538a5b9
user:      ad <ad%NetBSD.org@localhost>
date:      Wed Jan 22 12:00:18 2020 +0000

description:
Make sure LK_UPGRADE always comes with LK_NOWAIT; dropping the lock in here
is unclean and I wonder if it could screw over fstrans.

diffstat:

 sys/miscfs/genfs/genfs_vnops.c |  16 ++++++----------
 1 files changed, 6 insertions(+), 10 deletions(-)

diffs (46 lines):

diff -r 5a4f104cd914 -r 6d48c538a5b9 sys/miscfs/genfs/genfs_vnops.c
--- a/sys/miscfs/genfs/genfs_vnops.c    Wed Jan 22 11:40:16 2020 +0000
+++ b/sys/miscfs/genfs/genfs_vnops.c    Wed Jan 22 12:00:18 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: genfs_vnops.c,v 1.200.2.1 2020/01/18 17:12:59 ad Exp $ */
+/*     $NetBSD: genfs_vnops.c,v 1.200.2.2 2020/01/22 12:00:18 ad Exp $ */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -57,7 +57,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.200.2.1 2020/01/18 17:12:59 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.200.2.2 2020/01/22 12:00:18 ad Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -295,11 +295,9 @@
        if (ISSET(flags, LK_DOWNGRADE)) {
                rw_downgrade(vip->vi_lock);
        } else if (ISSET(flags, LK_UPGRADE)) {
+               KASSERT(ISSET(flags, LK_NOWAIT));
                if (!rw_tryupgrade(vip->vi_lock)) {
-                       if (ISSET(flags, LK_NOWAIT))
-                               return EBUSY;
-                       rw_exit(vip->vi_lock);
-                       rw_enter(vip->vi_lock, RW_WRITER);
+                       return EBUSY;
                }
        } else if ((flags & (LK_EXCLUSIVE | LK_SHARED)) != 0) {
                op = (ISSET(flags, LK_EXCLUSIVE) ? RW_WRITER : RW_READER);
@@ -349,11 +347,9 @@
        if (ISSET(flags, LK_DOWNGRADE)) {
                rw_downgrade(vip->vi_lock);
        } else if (ISSET(flags, LK_UPGRADE)) {
+               KASSERT(ISSET(flags, LK_NOWAIT));
                if (!rw_tryupgrade(vip->vi_lock)) {
-                       if (ISSET(flags, LK_NOWAIT))
-                               return EBUSY;
-                       rw_exit(vip->vi_lock);
-                       rw_enter(vip->vi_lock, RW_WRITER);
+                       return EBUSY;
                }
        } else if ((flags & (LK_EXCLUSIVE | LK_SHARED)) != 0) {
                op = (ISSET(flags, LK_EXCLUSIVE) ? RW_WRITER : RW_READER);