new locking scheme

SCCS-vsn: sys/miscfs/union/union.h 2.1
SCCS-vsn: sys/miscfs/union/union_subr.c 2.1
SCCS-vsn: sys/miscfs/union/union_vnops.c 2.1
SCCS-vsn: sys/miscfs/union/union_vfsops.c 2.1

diff --git a/usr/src/sys/miscfs/union/union.h b/usr/src/sys/miscfs/union/union.h
index 9657ba9..8041fb7 100644 (file)
--- a/usr/src/sys/miscfs/union/union.h
+++ b/usr/src/sys/miscfs/union/union.h
@@ -8,7 +8,7 @@
  *
  * %sccs.include.redist.c%
  *
  *
  * %sccs.include.redist.c%
  *

- *     @(#)union.h     1.9 (Berkeley) %G%
+ *     @(#)union.h     2.1 (Berkeley) %G%

  */
 
 struct union_args {
  */
 
 struct union_args {


@@ -56,8 +56,17 @@ struct union_node {
 #endif
 };
 
 #endif
 };
 

-#define UN_WANT 0x01
-#define UN_LOCKED 0x02
+#define UN_WANT                0x01
+#define UN_LOCKED      0x02
+#define UN_ULOCK       0x04            /* Upper node is locked */
+#define UN_KLOCK       0x08            /* Keep upper node locked on vput */
+
+#define LOCKUVP(un) \
+               (((un)->un_flags & UN_ULOCK) ? \
+                 (0) : \
+                 (((un)->un_flags |= UN_ULOCK), VOP_LOCK((un)->un_uppervp)))
+#define UNLOCKUVP(un) \
+               ((un)->un_flags &= ~UN_ULOCK)

 
 extern int union_allocvp __P((struct vnode **, struct mount *,
                                struct vnode *, struct vnode *,
 
 extern int union_allocvp __P((struct vnode **, struct mount *,
                                struct vnode *, struct vnode *,

diff --git a/usr/src/sys/miscfs/union/union_subr.c b/usr/src/sys/miscfs/union/union_subr.c
index 5e13601..3319a34 100644 (file)
--- a/usr/src/sys/miscfs/union/union_subr.c
+++ b/usr/src/sys/miscfs/union/union_subr.c
@@ -8,7 +8,7 @@
  *
  * %sccs.include.redist.c%
  *
  *
  * %sccs.include.redist.c%
  *

- *     @(#)union_subr.c        1.9 (Berkeley) %G%
+ *     @(#)union_subr.c        2.1 (Berkeley) %G%

  */
 
 #include <sys/param.h>
  */
 
 #include <sys/param.h>


@@ -37,6 +37,20 @@ union_init()
        unvplock = 0;
 }
 
        unvplock = 0;
 }
 

+static void
+union_remlist(un)
+       struct union_node *un;
+{
+       struct union_node **unpp;
+
+       for (unpp = &unhead; *unpp != 0; unpp = &(*unpp)->un_next) {
+               if (*unpp == un) {
+                       *unpp = un->un_next;
+                       break;
+               }
+       }
+}
+

 /*
  * allocate a union_node/vnode pair.  the vnode is
  * referenced and locked.  the new vnode is returned
 /*
  * allocate a union_node/vnode pair.  the vnode is
  * referenced and locked.  the new vnode is returned


@@ -47,6 +61,7 @@ union_init()
  * layer object to be created at a later time.  (uppervp)
  * and (lowervp) reference the upper and lower layer objects
  * being mapped.  either, but not both, can be nil.
  * layer object to be created at a later time.  (uppervp)
  * and (lowervp) reference the upper and lower layer objects
  * being mapped.  either, but not both, can be nil.

+ * if supplied, (uppervp) is locked.

  * the reference is either maintained in the new union_node
  * object which is allocated, or they are vrele'd.
  *
  * the reference is either maintained in the new union_node
  * object which is allocated, or they are vrele'd.
  *


@@ -99,50 +114,102 @@ loop:
                    (UNIONTOV(un)->v_mount == mp)) {
                        if (vget(UNIONTOV(un), 0))
                                goto loop;
                    (UNIONTOV(un)->v_mount == mp)) {
                        if (vget(UNIONTOV(un), 0))
                                goto loop;

-                       if (UNIONTOV(un) != undvp)
-                               VOP_LOCK(UNIONTOV(un));
+                       break;
+               }
+       }

 
 

+       if (un) {
+               /*
+                * Obtain a lock on the union_node.
+                * uppervp is locked, though un->un_uppervp
+                * may not be.  this doesn't break the locking
+                * hierarchy since in the case that un->un_uppervp
+                * is not yet locked it will be vrele'd and replaced
+                * with uppervp.
+                */
+
+               if ((dvp != NULLVP) && (uppervp == dvp)) {

                        /*
                        /*

-                        * Save information about the upper layer.
+                        * Access ``.'', so (un) will already
+                        * be locked.  Since this process has
+                        * the lock on (uppervp) no other
+                        * process can hold the lock on (un).

                         */
                         */

-                       if (uppervp != un->un_uppervp) {
-                               if (un->un_uppervp)
-                                       vrele(un->un_uppervp);
-                               un->un_uppervp = uppervp;
-                       } else if (uppervp) {
-                               vrele(uppervp);
+#ifdef DIAGNOSTIC
+                       if ((un->un_flags & UN_LOCKED) == 0)
+                               panic("union: . not locked");
+                       else if (curproc && un->un_pid != curproc->p_pid &&
+                                   un->un_pid > -1 && curproc->p_pid > -1)
+                               panic("union: allocvp not lock owner");
+#endif
+               } else {
+                       if (un->un_flags & UN_LOCKED) {
+                               vrele(UNIONTOV(un));
+                               un->un_flags |= UN_WANT;
+                               sleep((caddr_t) &un->un_flags, PINOD);
+                               goto loop;

                        }
                        }

+                       un->un_flags |= UN_LOCKED;

 
 

-                       /*
-                        * Save information about the lower layer.
-                        * This needs to keep track of pathname
-                        * and directory information which union_vn_create
-                        * might need.
-                        */
-                       if (lowervp != un->un_lowervp) {
-                               if (un->un_lowervp) {
-                                       vrele(un->un_lowervp);
-                                       free(un->un_path, M_TEMP);
-                                       vrele(un->un_dirvp);
-                               }
-                               un->un_lowervp = lowervp;
-                               if (cnp && (lowervp != NULLVP) &&
-                                   (lowervp->v_type == VREG)) {
-                                       un->un_hash = cnp->cn_hash;
-                                       un->un_path = malloc(cnp->cn_namelen+1,
-                                                       M_TEMP, M_WAITOK);
-                                       bcopy(cnp->cn_nameptr, un->un_path,
-                                                       cnp->cn_namelen);
-                                       un->un_path[cnp->cn_namelen] = '\0';
-                                       VREF(dvp);
-                                       un->un_dirvp = dvp;
-                               }
-                       } else if (lowervp) {
-                               vrele(lowervp);
+#ifdef DIAGNOSTIC
+                       if (curproc)
+                               un->un_pid = curproc->p_pid;
+                       else
+                               un->un_pid = -1;
+#endif
+               }
+
+               /*
+                * At this point, the union_node is locked,
+                * un->un_uppervp may not be locked, and uppervp
+                * is locked or nil.
+                */
+
+               /*
+                * Save information about the upper layer.
+                */
+               if (uppervp != un->un_uppervp) {
+                       if (un->un_uppervp)
+                               vrele(un->un_uppervp);
+                       un->un_uppervp = uppervp;
+               } else if (uppervp) {
+                       vrele(uppervp);
+               }
+
+               if (un->un_uppervp) {
+                       un->un_flags |= UN_ULOCK;
+                       un->un_flags &= ~UN_KLOCK;
+               }
+
+               /*
+                * Save information about the lower layer.
+                * This needs to keep track of pathname
+                * and directory information which union_vn_create
+                * might need.
+                */
+               if (lowervp != un->un_lowervp) {
+                       if (un->un_lowervp) {
+                               vrele(un->un_lowervp);
+                               free(un->un_path, M_TEMP);
+                               vrele(un->un_dirvp);
+                       }
+                       un->un_lowervp = lowervp;
+                       if (cnp && (lowervp != NULLVP) &&
+                           (lowervp->v_type == VREG)) {
+                               un->un_hash = cnp->cn_hash;
+                               un->un_path = malloc(cnp->cn_namelen+1,
+                                               M_TEMP, M_WAITOK);
+                               bcopy(cnp->cn_nameptr, un->un_path,
+                                               cnp->cn_namelen);
+                               un->un_path[cnp->cn_namelen] = '\0';
+                               VREF(dvp);
+                               un->un_dirvp = dvp;

                        }
                        }

-                       *vpp = UNIONTOV(un);
-                       return (0);
+               } else if (lowervp) {
+                       vrele(lowervp);

                }
                }

+               *vpp = UNIONTOV(un);
+               return (0);

        }
 
        /*
        }
 
        /*


@@ -157,8 +224,18 @@ loop:
        unvplock |= UN_LOCKED;
 
        error = getnewvnode(VT_UNION, mp, union_vnodeop_p, vpp);
        unvplock |= UN_LOCKED;
 
        error = getnewvnode(VT_UNION, mp, union_vnodeop_p, vpp);

-       if (error)
+       if (error) {
+               if (uppervp) {
+                       if (dvp == uppervp)
+                               vrele(uppervp);
+                       else
+                               vput(uppervp);
+               }
+               if (lowervp)
+                       vrele(lowervp);
+

                goto out;
                goto out;

+       }

 
        MALLOC((*vpp)->v_data, void *, sizeof(struct union_node),
                M_TEMP, M_WAITOK);
 
        MALLOC((*vpp)->v_data, void *, sizeof(struct union_node),
                M_TEMP, M_WAITOK);


@@ -173,7 +250,15 @@ loop:
        un->un_uppervp = uppervp;
        un->un_lowervp = lowervp;
        un->un_openl = 0;
        un->un_uppervp = uppervp;
        un->un_lowervp = lowervp;
        un->un_openl = 0;

-       un->un_flags = 0;
+       un->un_flags = UN_LOCKED;
+       if (un->un_uppervp)
+               un->un_flags |= UN_ULOCK;
+#ifdef DIAGNOSTIC
+       if (curproc)
+               un->un_pid = curproc->p_pid;
+       else
+               un->un_pid = -1;
+#endif

        if (cnp && (lowervp != NULLVP) && (lowervp->v_type == VREG)) {
                un->un_hash = cnp->cn_hash;
                un->un_path = malloc(cnp->cn_namelen+1, M_TEMP, M_WAITOK);
        if (cnp && (lowervp != NULLVP) && (lowervp->v_type == VREG)) {
                un->un_hash = cnp->cn_hash;
                un->un_path = malloc(cnp->cn_namelen+1, M_TEMP, M_WAITOK);


@@ -192,12 +277,6 @@ loop:
                continue;
        *pp = un;
 
                continue;
        *pp = un;
 

-       un->un_flags |= UN_LOCKED;
-
-#ifdef DIAGNOSTIC
-       un->un_pid = curproc->p_pid;
-#endif
-

        if (xlowervp)
                vrele(xlowervp);
 
        if (xlowervp)
                vrele(xlowervp);
 


@@ -216,15 +295,9 @@ int
 union_freevp(vp)
        struct vnode *vp;
 {
 union_freevp(vp)
        struct vnode *vp;
 {

-       struct union_node **unpp;

        struct union_node *un = VTOUNION(vp);
 
        struct union_node *un = VTOUNION(vp);
 

-       for (unpp = &unhead; *unpp != 0; unpp = &(*unpp)->un_next) {
-               if (*unpp == un) {
-                       *unpp = un->un_next;
-                       break;
-               }
-       }
+       union_remlist(un);

 
        FREE(vp->v_data, M_TEMP);
        vp->v_data = 0;
 
        FREE(vp->v_data, M_TEMP);
        vp->v_data = 0;


@@ -504,7 +577,12 @@ void
 union_removed_upper(un)
        struct union_node *un;
 {
 union_removed_upper(un)
        struct union_node *un;
 {

-       vrele(un->un_uppervp);
+       if (un->un_flags & UN_ULOCK) {
+               un->un_flags &= ~UN_ULOCK;
+               vput(un->un_uppervp);
+       } else {
+               vrele(un->un_uppervp);
+       }

        un->un_uppervp = NULLVP;
 }
 
        un->un_uppervp = NULLVP;
 }
 

diff --git a/usr/src/sys/miscfs/union/union_vfsops.c b/usr/src/sys/miscfs/union/union_vfsops.c
index 2139392..0df9f55 100644 (file)
--- a/usr/src/sys/miscfs/union/union_vfsops.c
+++ b/usr/src/sys/miscfs/union/union_vfsops.c
@@ -8,7 +8,7 @@
  *
  * %sccs.include.redist.c%
  *
  *
  * %sccs.include.redist.c%
  *

- *     @(#)union_vfsops.c      1.9 (Berkeley) %G%
+ *     @(#)union_vfsops.c      2.1 (Berkeley) %G%

  */
 
 /*
  */
 
 /*


@@ -309,6 +309,7 @@ union_root(mp, vpp)
         * Return locked reference to root.
         */
        VREF(um->um_uppervp);
         * Return locked reference to root.
         */
        VREF(um->um_uppervp);

+       VOP_LOCK(um->um_uppervp);

        if (um->um_lowervp)
                VREF(um->um_lowervp);
        error = union_allocvp(vpp, mp,
        if (um->um_lowervp)
                VREF(um->um_lowervp);
        error = union_allocvp(vpp, mp,

diff --git a/usr/src/sys/miscfs/union/union_vnops.c b/usr/src/sys/miscfs/union/union_vnops.c
index 6363f71..9a2e248 100644 (file)
--- a/usr/src/sys/miscfs/union/union_vnops.c
+++ b/usr/src/sys/miscfs/union/union_vnops.c
@@ -8,7 +8,7 @@
  *
  * %sccs.include.redist.c%
  *
  *
  * %sccs.include.redist.c%
  *

- *     @(#)union_vnops.c       1.9 (Berkeley) %G%
+ *     @(#)union_vnops.c       2.1 (Berkeley) %G%

  */
 
 #include <sys/param.h>
  */
 
 #include <sys/param.h>


@@ -135,11 +135,10 @@ union_lookup(ap)
         * on and just return that vnode.
         */
        if (upperdvp) {
         * on and just return that vnode.
         */
        if (upperdvp) {

-               VOP_LOCK(upperdvp);

                uerror = union_lookup1(um->um_uppervp, upperdvp,
                                        &uppervp, cnp);
                uerror = union_lookup1(um->um_uppervp, upperdvp,
                                        &uppervp, cnp);

-               if (uppervp != upperdvp)
-                       VOP_UNLOCK(upperdvp);
+               /*if (uppervp == upperdvp)
+                       dun->un_flags |= UN_KLOCK;*/

 
                if (cnp->cn_consume != 0) {
                        *ap->a_vpp = uppervp;
 
                if (cnp->cn_consume != 0) {
                        *ap->a_vpp = uppervp;


@@ -159,15 +158,29 @@ union_lookup(ap)
         * instead.
         */
        if (lowerdvp) {
         * instead.
         */
        if (lowerdvp) {

+               int nameiop;
+

                VOP_LOCK(lowerdvp);
                VOP_LOCK(lowerdvp);

+
+               /*
+                * Only do a LOOKUP on the bottom node, since
+                * we won't be making changes to it anyway.
+                */
+               nameiop = cnp->cn_nameiop;
+               cnp->cn_nameiop = LOOKUP;

                lerror = union_lookup1(um->um_lowervp, lowerdvp,
                lerror = union_lookup1(um->um_lowervp, lowerdvp,

-                                       &lowervp, cnp);
+                               &lowervp, cnp);
+               cnp->cn_nameiop = nameiop;
+

                if (lowervp != lowerdvp)
                        VOP_UNLOCK(lowerdvp);
 
                if (cnp->cn_consume != 0) {
                        if (uppervp) {
                if (lowervp != lowerdvp)
                        VOP_UNLOCK(lowerdvp);
 
                if (cnp->cn_consume != 0) {
                        if (uppervp) {

-                               vput(uppervp);
+                               if (uppervp == upperdvp)
+                                       vrele(uppervp);
+                               else
+                                       vput(uppervp);

                                uppervp = NULLVP;
                        }
                        *ap->a_vpp = lowervp;
                                uppervp = NULLVP;
                        }
                        *ap->a_vpp = lowervp;


@@ -216,7 +229,12 @@ union_lookup(ap)
        /* case 2. */
        if (uerror != 0 /* && (lerror == 0) */ ) {
                if (lowervp->v_type == VDIR) { /* case 2b. */
        /* case 2. */
        if (uerror != 0 /* && (lerror == 0) */ ) {
                if (lowervp->v_type == VDIR) { /* case 2b. */

+                       dun->un_flags &= ~UN_ULOCK;
+                       VOP_UNLOCK(upperdvp);

                        uerror = union_mkshadow(um, upperdvp, cnp, &uppervp);
                        uerror = union_mkshadow(um, upperdvp, cnp, &uppervp);

+                       VOP_LOCK(upperdvp);
+                       dun->un_flags |= UN_ULOCK;
+

                        if (uerror) {
                                if (lowervp) {
                                        vput(lowervp);
                        if (uerror) {
                                if (lowervp) {
                                        vput(lowervp);


@@ -227,8 +245,6 @@ union_lookup(ap)
                }
        }
 
                }
        }
 

-       if (uppervp)
-               VOP_UNLOCK(uppervp);

        if (lowervp)
                VOP_UNLOCK(lowervp);
 
        if (lowervp)
                VOP_UNLOCK(lowervp);
 


@@ -237,7 +253,7 @@ union_lookup(ap)
 
        if (error) {
                if (uppervp)
 
        if (error) {
                if (uppervp)

-                       vrele(uppervp);
+                       vput(uppervp);

                if (lowervp)
                        vrele(lowervp);
        } else {
                if (lowervp)
                        vrele(lowervp);
        } else {


@@ -266,14 +282,12 @@ union_create(ap)
                struct vnode *vp;
 
                VREF(dvp);
                struct vnode *vp;
 
                VREF(dvp);

-               VOP_LOCK(dvp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_dvp);
                error = VOP_CREATE(dvp, &vp, ap->a_cnp, ap->a_vap);
                if (error)
                        return (error);
 
                vput(ap->a_dvp);
                error = VOP_CREATE(dvp, &vp, ap->a_cnp, ap->a_vap);
                if (error)
                        return (error);
 

-               VOP_UNLOCK(vp);
-

                error = union_allocvp(
                                ap->a_vpp,
                                ap->a_dvp->v_mount,
                error = union_allocvp(
                                ap->a_vpp,
                                ap->a_dvp->v_mount,


@@ -283,7 +297,7 @@ union_create(ap)
                                vp,
                                NULLVP);
                if (error)
                                vp,
                                NULLVP);
                if (error)

-                       vrele(vp);
+                       vput(vp);

                return (error);
        }
 
                return (error);
        }
 


@@ -308,15 +322,13 @@ union_mknod(ap)
                struct vnode *vp;
 
                VREF(dvp);
                struct vnode *vp;
 
                VREF(dvp);

-               VOP_LOCK(dvp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_dvp);
                error = VOP_MKNOD(dvp, &vp, ap->a_cnp, ap->a_vap);
                if (error)
                        return (error);
 
                if (vp) {
                vput(ap->a_dvp);
                error = VOP_MKNOD(dvp, &vp, ap->a_cnp, ap->a_vap);
                if (error)
                        return (error);
 
                if (vp) {

-                       VOP_UNLOCK(vp);
-

                        error = union_allocvp(
                                        ap->a_vpp,
                                        ap->a_dvp->v_mount,
                        error = union_allocvp(
                                        ap->a_vpp,
                                        ap->a_dvp->v_mount,


@@ -326,7 +338,7 @@ union_mknod(ap)
                                        vp,
                                        NULLVP);
                        if (error)
                                        vp,
                                        NULLVP);
                        if (error)

-                               vrele(vp);
+                               vput(vp);

                }
                return (error);
        }
                }
                return (error);
        }


@@ -380,8 +392,10 @@ union_open(ap)
                        error = union_vn_create(&vp, un, p);
                        if (error)
                                return (error);
                        error = union_vn_create(&vp, un, p);
                        if (error)
                                return (error);

-                       un->un_uppervp = vp;    /* XXX */
+

                        /* at this point, uppervp is locked */
                        /* at this point, uppervp is locked */

+                       un->un_uppervp = vp;    /* XXX */
+                       un->un_flags |= UN_ULOCK;

 
                        /*
                         * Now, if the file is being opened with truncation,
 
                        /*
                         * Now, if the file is being opened with truncation,


@@ -405,9 +419,13 @@ union_open(ap)
                                } else {
                                        VOP_UNLOCK(tvp);
                                }
                                } else {
                                        VOP_UNLOCK(tvp);
                                }

+
+                               un->un_flags &= ~UN_ULOCK;

                                VOP_UNLOCK(un->un_uppervp);
                                union_vn_close(un->un_uppervp, FWRITE, cred, p);
                                VOP_LOCK(un->un_uppervp);
                                VOP_UNLOCK(un->un_uppervp);
                                union_vn_close(un->un_uppervp, FWRITE, cred, p);
                                VOP_LOCK(un->un_uppervp);

+                               un->un_flags |= UN_ULOCK;
+

                                if (!error)
                                        uprintf("union: copied up %s\n",
                                                                un->un_path);
                                if (!error)
                                        uprintf("union: copied up %s\n",
                                                                un->un_path);


@@ -429,15 +447,21 @@ union_open(ap)
 
                        if (error == 0)
                                error = VOP_OPEN(un->un_uppervp, mode, cred, p);
 
                        if (error == 0)
                                error = VOP_OPEN(un->un_uppervp, mode, cred, p);

-                       VOP_UNLOCK(un->un_uppervp);

                        return (error);
                }
                        return (error);
                }

+
+               /*
+                * Just open the lower vnode
+                */

                un->un_openl++;
                un->un_openl++;

+               VOP_LOCK(tvp);
+               error = VOP_OPEN(tvp, mode, cred, p);
+               VOP_UNLOCK(tvp);
+
+               return (error);

        }
 
        }
 

-       VOP_LOCK(tvp);

        error = VOP_OPEN(tvp, mode, cred, p);
        error = VOP_OPEN(tvp, mode, cred, p);

-       VOP_UNLOCK(tvp);

 
        return (error);
 }
 
        return (error);
 }


@@ -498,11 +522,8 @@ union_access(ap)
                        return (error);
        }
 
                        return (error);
        }
 

-       if (vp = un->un_uppervp) {
-               VOP_LOCK(vp);
+       if (vp = un->un_uppervp)

                error = VOP_ACCESS(vp, ap->a_mode, ap->a_cred, ap->a_p);
                error = VOP_ACCESS(vp, ap->a_mode, ap->a_cred, ap->a_p);

-               VOP_UNLOCK(vp);
-       }

 
        return (error);
 }
 
        return (error);
 }


@@ -521,10 +542,13 @@ union_getattr(ap)
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);

+       int dolock = (vp == LOWERVP(ap->a_vp));

 
 

-       VOP_LOCK(vp);
+       if (dolock)
+               VOP_LOCK(vp);

        error = VOP_GETATTR(vp, ap->a_vap, ap->a_cred, ap->a_p);
        error = VOP_GETATTR(vp, ap->a_vap, ap->a_cred, ap->a_p);

-       VOP_UNLOCK(vp);
+       if (dolock)
+               VOP_UNLOCK(vp);

 
        /* Requires that arguments be restored. */
        ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
 
        /* Requires that arguments be restored. */
        ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];


@@ -544,10 +568,8 @@ union_setattr(ap)
        int error;
 
        if (un->un_uppervp) {
        int error;
 
        if (un->un_uppervp) {

-               VOP_LOCK(un->un_uppervp);

                error = VOP_SETATTR(un->un_uppervp, ap->a_vap,
                                        ap->a_cred, ap->a_p);
                error = VOP_SETATTR(un->un_uppervp, ap->a_vap,
                                        ap->a_cred, ap->a_p);

-               VOP_UNLOCK(un->un_uppervp);

        } else {
                /*
                 * XXX should do a copyfile (perhaps only if
        } else {
                /*
                 * XXX should do a copyfile (perhaps only if


@@ -571,10 +593,13 @@ union_read(ap)
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);

+       int dolock = (vp == LOWERVP(ap->a_vp));

 
 

-       VOP_LOCK(vp);
+       if (dolock)
+               VOP_LOCK(vp);

        error = VOP_READ(vp, ap->a_uio, ap->a_ioflag, ap->a_cred);
        error = VOP_READ(vp, ap->a_uio, ap->a_ioflag, ap->a_cred);

-       VOP_UNLOCK(vp);
+       if (dolock)
+               VOP_UNLOCK(vp);

 
        return (error);
 }
 
        return (error);
 }


@@ -590,10 +615,13 @@ union_write(ap)
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);

+       int dolock = (vp == LOWERVP(ap->a_vp));

 
 

-       VOP_LOCK(vp);
+       if (dolock)
+               VOP_LOCK(vp);

        error = VOP_WRITE(vp, ap->a_uio, ap->a_ioflag, ap->a_cred);
        error = VOP_WRITE(vp, ap->a_uio, ap->a_ioflag, ap->a_cred);

-       VOP_UNLOCK(vp);
+       if (dolock)
+               VOP_UNLOCK(vp);

 
        return (error);
 }
 
        return (error);
 }


@@ -656,10 +684,14 @@ union_fsync(ap)
        struct vnode *targetvp = OTHERVP(ap->a_vp);
 
        if (targetvp) {
        struct vnode *targetvp = OTHERVP(ap->a_vp);
 
        if (targetvp) {

-               VOP_LOCK(targetvp);
+               int dolock = (targetvp == LOWERVP(ap->a_vp));
+
+               if (dolock)
+                       VOP_LOCK(targetvp);

                error = VOP_FSYNC(targetvp, ap->a_cred,
                                        ap->a_waitfor, ap->a_p);
                error = VOP_FSYNC(targetvp, ap->a_cred,
                                        ap->a_waitfor, ap->a_p);

-               VOP_UNLOCK(targetvp);
+               if (dolock)
+                       VOP_UNLOCK(targetvp);

        }
 
        return (error);
        }
 
        return (error);


@@ -695,10 +727,10 @@ union_remove(ap)
                struct vnode *vp = un->un_uppervp;
 
                VREF(dvp);
                struct vnode *vp = un->un_uppervp;
 
                VREF(dvp);

-               VOP_LOCK(dvp);
+               dun->un_flags |= UN_KLOCK;

                vput(ap->a_dvp);
                VREF(vp);
                vput(ap->a_dvp);
                VREF(vp);

-               VOP_LOCK(vp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_vp);
 
                error = VOP_REMOVE(dvp, vp, ap->a_cnp);
                vput(ap->a_vp);
 
                error = VOP_REMOVE(dvp, vp, ap->a_cnp);


@@ -737,7 +769,7 @@ union_link(ap)
                struct vnode *vp = un->un_uppervp;
 
                VREF(dvp);
                struct vnode *vp = un->un_uppervp;
 
                VREF(dvp);

-               VOP_LOCK(dvp);
+               dun->un_flags |= UN_KLOCK;

                vput(ap->a_vp);
                VREF(vp);
                vrele(ap->a_tdvp);
                vput(ap->a_vp);
                VREF(vp);
                vrele(ap->a_tdvp);


@@ -807,7 +839,7 @@ union_rename(ap)
 
                tdvp = un->un_uppervp;
                VREF(tdvp);
 
                tdvp = un->un_uppervp;
                VREF(tdvp);

-               VOP_LOCK(tdvp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_tdvp);
        }
 
                vput(ap->a_tdvp);
        }
 


@@ -820,7 +852,7 @@ union_rename(ap)
 
                tvp = un->un_uppervp;
                VREF(tvp);
 
                tvp = un->un_uppervp;
                VREF(tvp);

-               VOP_LOCK(tvp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_tvp);
        }
 
                vput(ap->a_tvp);
        }
 


@@ -853,13 +885,12 @@ union_mkdir(ap)
                struct vnode *vp;
 
                VREF(dvp);
                struct vnode *vp;
 
                VREF(dvp);

-               VOP_LOCK(dvp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_dvp);
                error = VOP_MKDIR(dvp, &vp, ap->a_cnp, ap->a_vap);
                if (error)
                        return (error);
 
                vput(ap->a_dvp);
                error = VOP_MKDIR(dvp, &vp, ap->a_cnp, ap->a_vap);
                if (error)
                        return (error);
 

-               VOP_UNLOCK(vp);

                error = union_allocvp(
                                ap->a_vpp,
                                ap->a_dvp->v_mount,
                error = union_allocvp(
                                ap->a_vpp,
                                ap->a_dvp->v_mount,


@@ -869,7 +900,7 @@ union_mkdir(ap)
                                vp,
                                NULLVP);
                if (error)
                                vp,
                                NULLVP);
                if (error)

-                       vrele(vp);
+                       vput(vp);

                return (error);
        }
 
                return (error);
        }
 


@@ -894,13 +925,13 @@ union_rmdir(ap)
                struct vnode *vp = un->un_uppervp;
 
                VREF(dvp);
                struct vnode *vp = un->un_uppervp;
 
                VREF(dvp);

-               VOP_LOCK(dvp);
+               dun->un_flags |= UN_KLOCK;

                vput(ap->a_dvp);
                VREF(vp);
                vput(ap->a_dvp);
                VREF(vp);

-               VOP_LOCK(vp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_vp);
 
                vput(ap->a_vp);
 

-               error = VOP_REMOVE(dvp, vp, ap->a_cnp);
+               error = VOP_RMDIR(dvp, vp, ap->a_cnp);

                if (!error)
                        union_removed_upper(un);
 
                if (!error)
                        union_removed_upper(un);
 


@@ -938,7 +969,7 @@ union_symlink(ap)
                struct mount *mp = ap->a_dvp->v_mount;
 
                VREF(dvp);
                struct mount *mp = ap->a_dvp->v_mount;
 
                VREF(dvp);

-               VOP_LOCK(dvp);
+               un->un_flags |= UN_KLOCK;

                vput(ap->a_dvp);
                error = VOP_SYMLINK(dvp, &vp, ap->a_cnp,
                                        ap->a_vap, ap->a_target);
                vput(ap->a_dvp);
                error = VOP_SYMLINK(dvp, &vp, ap->a_cnp,
                                        ap->a_vap, ap->a_target);


@@ -969,13 +1000,8 @@ union_readdir(ap)
        int error = 0;
        struct union_node *un = VTOUNION(ap->a_vp);
 
        int error = 0;
        struct union_node *un = VTOUNION(ap->a_vp);
 

-       if (un->un_uppervp) {
-               struct vnode *vp = un->un_uppervp;
-
-               VOP_LOCK(vp);
-               error = VOP_READLINK(vp, ap->a_uio, ap->a_cred);
-               VOP_UNLOCK(vp);
-       }
+       if (un->un_uppervp)
+               error = VOP_READDIR(un->un_uppervp, ap->a_uio, ap->a_cred);

 
        return (error);
 }
 
        return (error);
 }


@@ -990,10 +1016,13 @@ union_readlink(ap)
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);

+       int dolock = (vp == LOWERVP(ap->a_vp));

 
 

-       VOP_LOCK(vp);
+       if (dolock)
+               VOP_LOCK(vp);

        error = VOP_READLINK(vp, ap->a_uio, ap->a_cred);
        error = VOP_READLINK(vp, ap->a_uio, ap->a_cred);

-       VOP_UNLOCK(vp);
+       if (dolock)
+               VOP_UNLOCK(vp);

 
        return (error);
 }
 
        return (error);
 }


@@ -1009,11 +1038,12 @@ union_abortop(ap)
        struct vnode *vp = OTHERVP(ap->a_dvp);
        struct union_node *un = VTOUNION(ap->a_dvp);
        int islocked = un->un_flags & UN_LOCKED;
        struct vnode *vp = OTHERVP(ap->a_dvp);
        struct union_node *un = VTOUNION(ap->a_dvp);
        int islocked = un->un_flags & UN_LOCKED;

+       int dolock = (vp == LOWERVP(ap->a_dvp));

 
 

-       if (islocked)
+       if (islocked && dolock)

                VOP_LOCK(vp);
        error = VOP_ABORTOP(vp, ap->a_cnp);
                VOP_LOCK(vp);
        error = VOP_ABORTOP(vp, ap->a_cnp);

-       if (islocked)
+       if (islocked && dolock)

                VOP_UNLOCK(vp);
 
        return (error);
                VOP_UNLOCK(vp);
 
        return (error);


@@ -1089,6 +1119,17 @@ union_lock(ap)
 {
        struct union_node *un = VTOUNION(ap->a_vp);
 
 {
        struct union_node *un = VTOUNION(ap->a_vp);
 

+       if (un->un_uppervp) {
+               if ((un->un_flags & UN_ULOCK) == 0) {
+                       VOP_LOCK(un->un_uppervp);
+                       un->un_flags |= UN_ULOCK;
+               }
+#ifdef DIAGNOSTIC
+               if (un->un_flags & UN_KLOCK)
+                       panic("union: dangling upper lock");
+#endif
+       }
+

        while (un->un_flags & UN_LOCKED) {
 #ifdef DIAGNOSTIC
                if (curproc && un->un_pid == curproc->p_pid &&
        while (un->un_flags & UN_LOCKED) {
 #ifdef DIAGNOSTIC
                if (curproc && un->un_pid == curproc->p_pid &&


@@ -1125,6 +1166,12 @@ union_unlock(ap)
 #endif
 
        un->un_flags &= ~UN_LOCKED;
 #endif
 
        un->un_flags &= ~UN_LOCKED;

+
+       if ((un->un_flags & (UN_ULOCK|UN_KLOCK)) == UN_ULOCK)
+               VOP_UNLOCK(un->un_uppervp);
+
+       un->un_flags &= ~(UN_ULOCK|UN_KLOCK);
+

        if (un->un_flags & UN_WANT) {
                un->un_flags &= ~UN_WANT;
                wakeup((caddr_t) &un->un_flags);
        if (un->un_flags & UN_WANT) {
                un->un_flags &= ~UN_WANT;
                wakeup((caddr_t) &un->un_flags);


@@ -1149,10 +1196,13 @@ union_bmap(ap)
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);

+       int dolock = (vp == LOWERVP(ap->a_vp));

 
 

-       VOP_LOCK(vp);
+       if (dolock)
+               VOP_LOCK(vp);

        error = VOP_BMAP(vp, ap->a_bn, ap->a_vpp, ap->a_bnp, ap->a_runp);
        error = VOP_BMAP(vp, ap->a_bn, ap->a_vpp, ap->a_bnp, ap->a_runp);

-       VOP_UNLOCK(vp);
+       if (dolock)
+               VOP_UNLOCK(vp);

 
        return (error);
 }
 
        return (error);
 }


@@ -1190,10 +1240,13 @@ union_pathconf(ap)
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);
 {
        int error;
        struct vnode *vp = OTHERVP(ap->a_vp);

+       int dolock = (vp == LOWERVP(ap->a_vp));

 
 

-       VOP_LOCK(vp);
+       if (dolock)
+               VOP_LOCK(vp);

        error = VOP_PATHCONF(vp, ap->a_name, ap->a_retval);
        error = VOP_PATHCONF(vp, ap->a_name, ap->a_retval);

-       VOP_UNLOCK(vp);
+       if (dolock)
+               VOP_UNLOCK(vp);

 
        return (error);
 }
 
        return (error);
 }