[src/trunk]: src/sys/miscfs/genfs Restructure genfs_deadlock() and genfs_lock...

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

details:   https://anonhg.NetBSD.org/src/rev/e2e3bd8f805a
branches:  trunk
changeset: 327593:e2e3bd8f805a
user:      hannken <hannken%NetBSD.org@localhost>
date:      Wed Mar 12 09:38:51 2014 +0000

description:
Restructure genfs_deadlock() and genfs_lock() to always lock before
testing for dead node.  Use ISSET() to test flags, add assertions.

Save the mount for fstrans_done() before genfs_unlock() unlocks the node.

diffstat:

 sys/miscfs/genfs/genfs_vnops.c |  94 ++++++++++++++++++++++++-----------------
 1 files changed, 55 insertions(+), 39 deletions(-)

diffs (155 lines):

diff -r 5722ed3f3327 -r e2e3bd8f805a sys/miscfs/genfs/genfs_vnops.c
--- a/sys/miscfs/genfs/genfs_vnops.c    Wed Mar 12 08:36:59 2014 +0000
+++ b/sys/miscfs/genfs/genfs_vnops.c    Wed Mar 12 09:38:51 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: genfs_vnops.c,v 1.190 2014/02/27 16:51:38 hannken Exp $        */
+/*     $NetBSD: genfs_vnops.c,v 1.191 2014/03/12 09:38:51 hannken Exp $        */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -57,7 +57,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.190 2014/02/27 16:51:38 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.191 2014/03/12 09:38:51 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -290,33 +290,42 @@
        struct vnode *vp = ap->a_vp;
        int flags = ap->a_flags;
        krw_t op;
-
-       if ((flags & LK_NOWAIT) != 0) {
-               if (!mutex_tryenter(vp->v_interlock))
-                       return EBUSY;
-               if ((vp->v_iflag & VI_XLOCK)) {
-                       mutex_exit(vp->v_interlock);
-                       return EBUSY;
-               }
-       }
+       int error;
 
-       mutex_enter(vp->v_interlock);
-       if ((vp->v_iflag & VI_XLOCK))
-               vwait(vp, VI_XLOCK);
-       mutex_exit(vp->v_interlock);
-
-       if ((flags & LK_RETRY) == 0)
-               return ENOENT;
-
-       op = ((flags & LK_EXCLUSIVE) != 0 ? RW_WRITER : RW_READER);
-       if ((flags & LK_NOWAIT) != 0) {
+       op = (ISSET(flags, LK_EXCLUSIVE) ? RW_WRITER : RW_READER);
+       if (ISSET(flags, LK_NOWAIT)) {
                if (! rw_tryenter(&vp->v_lock, op))
                        return EBUSY;
-               return 0;
+               if (mutex_tryenter(vp->v_interlock)) {
+                       if (ISSET(vp->v_iflag, VI_XLOCK))
+                               error = EBUSY;
+                       else {
+                               KASSERT(ISSET(vp->v_iflag, VI_CLEAN));
+                               error = (ISSET(flags, LK_RETRY) ? 0 : ENOENT);
+                       }
+                       mutex_exit(vp->v_interlock);
+               } else
+                       error = EBUSY;
+               if (error)
+                       rw_exit(&vp->v_lock);
+               return error;
        }
 
        rw_enter(&vp->v_lock, op);
-
+       mutex_enter(vp->v_interlock);
+       if (ISSET(vp->v_iflag, VI_XLOCK)) {
+               rw_exit(&vp->v_lock);
+               vwait(vp, VI_XLOCK);
+               mutex_exit(vp->v_interlock);
+               rw_enter(&vp->v_lock, op);
+               mutex_enter(vp->v_interlock);
+       }
+       KASSERT(ISSET(vp->v_iflag, VI_CLEAN));
+       mutex_exit(vp->v_interlock);
+       if (! ISSET(flags, LK_RETRY)) {
+               rw_exit(&vp->v_lock);
+               return ENOENT;
+       }
        return 0;
 }
 
@@ -350,39 +359,45 @@
        struct mount *mp = vp->v_mount;
        int flags = ap->a_flags;
        krw_t op;
+       int error;
 
-       op = ((flags & LK_EXCLUSIVE) != 0 ? RW_WRITER : RW_READER);
-       if ((flags & LK_NOWAIT) != 0) {
-               if (!mutex_tryenter(vp->v_interlock))
-                       return EBUSY;
-               if ((vp->v_iflag & (VI_XLOCK | VI_CLEAN)) != 0) {
-                       mutex_exit(vp->v_interlock);
-                       return EBUSY;
-               }
-               mutex_exit(vp->v_interlock);
+       op = (ISSET(flags, LK_EXCLUSIVE) ? RW_WRITER : RW_READER);
+       if (ISSET(flags, LK_NOWAIT)) {
                if (fstrans_start_nowait(mp, FSTRANS_SHARED))
                        return EBUSY;
                if (! rw_tryenter(&vp->v_lock, op)) {
                        fstrans_done(mp);
                        return EBUSY;
                }
-               return 0;
+               if (mutex_tryenter(vp->v_interlock)) {
+                       if (ISSET(vp->v_iflag, VI_XLOCK))
+                               error = EBUSY;
+                       else if (ISSET(vp->v_iflag, VI_CLEAN))
+                               error = ENOENT;
+                       else
+                               error = 0;
+                       mutex_exit(vp->v_interlock);
+               } else
+                       error = EBUSY;
+               if (error) {
+                       rw_exit(&vp->v_lock);
+                       fstrans_done(mp);
+               }
+               return error;
        }
 
        fstrans_start(mp, FSTRANS_SHARED);
        rw_enter(&vp->v_lock, op);
-
        mutex_enter(vp->v_interlock);
-       if ((vp->v_iflag & (VI_XLOCK | VI_CLEAN)) != 0) {
+       if (ISSET(vp->v_iflag, VI_XLOCK) || ISSET(vp->v_iflag, VI_CLEAN)) {
                rw_exit(&vp->v_lock);
                fstrans_done(mp);
-               if ((vp->v_iflag & VI_XLOCK))
-                       vwait(vp, VI_XLOCK);
+               vwait(vp, VI_XLOCK);
+               KASSERT(ISSET(vp->v_iflag, VI_CLEAN));
                mutex_exit(vp->v_interlock);
                return ENOENT;
        }
        mutex_exit(vp->v_interlock);
-
        return 0;
 }
 
@@ -396,9 +411,10 @@
                struct vnode *a_vp;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
+       struct mount *mp = vp->v_mount;
 
        rw_exit(&vp->v_lock);
-       fstrans_done(vp->v_mount);
+       fstrans_done(mp);
 
        return 0;
 }