Index: head/sys/fs/pseudofs/pseudofs_vnops.c
===================================================================
--- head/sys/fs/pseudofs/pseudofs_vnops.c	(revision 351740)
+++ head/sys/fs/pseudofs/pseudofs_vnops.c	(revision 351741)
@@ -1,1064 +1,1092 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer
  *    in this position and unchanged.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include "opt_pseudofs.h"
 
 #include <sys/param.h>
 #include <sys/kernel.h>
 #include <sys/systm.h>
 #include <sys/ctype.h>
 #include <sys/dirent.h>
 #include <sys/fcntl.h>
 #include <sys/limits.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/mount.h>
 #include <sys/mutex.h>
 #include <sys/namei.h>
 #include <sys/proc.h>
 #include <sys/sbuf.h>
 #include <sys/sx.h>
 #include <sys/sysctl.h>
 #include <sys/vnode.h>
 
 #include <fs/pseudofs/pseudofs.h>
 #include <fs/pseudofs/pseudofs_internal.h>
 
 #define KASSERT_PN_IS_DIR(pn)						\
 	KASSERT((pn)->pn_type == pfstype_root ||			\
 	    (pn)->pn_type == pfstype_dir ||				\
 	    (pn)->pn_type == pfstype_procdir,				\
 	    ("%s(): VDIR vnode refers to non-directory pfs_node", __func__))
 
 #define KASSERT_PN_IS_FILE(pn)						\
 	KASSERT((pn)->pn_type == pfstype_file,				\
 	    ("%s(): VREG vnode refers to non-file pfs_node", __func__))
 
 #define KASSERT_PN_IS_LINK(pn)						\
 	KASSERT((pn)->pn_type == pfstype_symlink,			\
 	    ("%s(): VLNK vnode refers to non-link pfs_node", __func__))
 
 /*
  * Returns the fileno, adjusted for target pid
  */
 static uint32_t
 pn_fileno(struct pfs_node *pn, pid_t pid)
 {
 
 	KASSERT(pn->pn_fileno > 0,
 	    ("%s(): no fileno allocated", __func__));
 	if (pid != NO_PID)
 		return (pn->pn_fileno * NO_PID + pid);
 	return (pn->pn_fileno);
 }
 
 /*
  * Returns non-zero if given file is visible to given thread.
  */
 static int
 pfs_visible_proc(struct thread *td, struct pfs_node *pn, struct proc *proc)
 {
 	int visible;
 
 	if (proc == NULL)
 		return (0);
 
 	PROC_LOCK_ASSERT(proc, MA_OWNED);
 
 	visible = ((proc->p_flag & P_WEXIT) == 0);
 	if (visible)
 		visible = (p_cansee(td, proc) == 0);
 	if (visible && pn->pn_vis != NULL)
 		visible = pn_vis(td, proc, pn);
 	if (!visible)
 		return (0);
 	return (1);
 }
 
 static int
 pfs_visible(struct thread *td, struct pfs_node *pn, pid_t pid,
     struct proc **p)
 {
 	struct proc *proc;
 
 	PFS_TRACE(("%s (pid: %d, req: %d)",
 	    pn->pn_name, pid, td->td_proc->p_pid));
 
 	if (p)
 		*p = NULL;
 	if (pid == NO_PID)
 		PFS_RETURN (1);
 	proc = pfind(pid);
 	if (proc == NULL)
 		PFS_RETURN (0);
 	if (pfs_visible_proc(td, pn, proc)) {
 		if (p)
 			*p = proc;
 		else
 			PROC_UNLOCK(proc);
 		PFS_RETURN (1);
 	}
 	PROC_UNLOCK(proc);
 	PFS_RETURN (0);
 }
 
+static int
+pfs_lookup_proc(pid_t pid, struct proc **p)
+{
+	struct proc *proc;
+
+	proc = pfind(pid);
+	if (proc == NULL)
+		return (0);
+	if ((proc->p_flag & P_WEXIT) != 0) {
+		PROC_UNLOCK(proc);
+		return (0);
+	}
+	_PHOLD(proc);
+	PROC_UNLOCK(proc);
+	*p = proc;
+	return (1);
+}
+
 /*
  * Verify permissions
  */
 static int
 pfs_access(struct vop_access_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct vattr vattr;
 	int error;
 
 	PFS_TRACE(("%s", pvd->pvd_pn->pn_name));
 	(void)pvd;
 
 	error = VOP_GETATTR(vn, &vattr, va->a_cred);
 	if (error)
 		PFS_RETURN (error);
 	error = vaccess(vn->v_type, vattr.va_mode, vattr.va_uid,
 	    vattr.va_gid, va->a_accmode, va->a_cred, NULL);
 	PFS_RETURN (error);
 }
 
 /*
  * Close a file or directory
  */
 static int
 pfs_close(struct vop_close_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 	struct proc *proc;
 	int error;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	/*
 	 * Do nothing unless this is the last close and the node has a
 	 * last-close handler.
 	 */
 	if (vrefcnt(vn) > 1 || pn->pn_close == NULL)
 		PFS_RETURN (0);
 
 	if (pvd->pvd_pid != NO_PID) {
 		proc = pfind(pvd->pvd_pid);
 	} else {
 		proc = NULL;
 	}
 
 	error = pn_close(va->a_td, proc, pn);
 
 	if (proc != NULL)
 		PROC_UNLOCK(proc);
 
 	PFS_RETURN (error);
 }
 
 /*
  * Get file attributes
  */
 static int
 pfs_getattr(struct vop_getattr_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 	struct vattr *vap = va->a_vap;
 	struct proc *proc;
 	int error = 0;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
 		PFS_RETURN (ENOENT);
 
 	vap->va_type = vn->v_type;
 	vap->va_fileid = pn_fileno(pn, pvd->pvd_pid);
 	vap->va_flags = 0;
 	vap->va_blocksize = PAGE_SIZE;
 	vap->va_bytes = vap->va_size = 0;
 	vap->va_filerev = 0;
 	vap->va_fsid = vn->v_mount->mnt_stat.f_fsid.val[0];
 	vap->va_nlink = 1;
 	nanotime(&vap->va_ctime);
 	vap->va_atime = vap->va_mtime = vap->va_ctime;
 
 	switch (pn->pn_type) {
 	case pfstype_procdir:
 	case pfstype_root:
 	case pfstype_dir:
 #if 0
 		pfs_lock(pn);
 		/* compute link count */
 		pfs_unlock(pn);
 #endif
 		vap->va_mode = 0555;
 		break;
 	case pfstype_file:
 	case pfstype_symlink:
 		vap->va_mode = 0444;
 		break;
 	default:
 		printf("shouldn't be here!\n");
 		vap->va_mode = 0;
 		break;
 	}
 
 	if (proc != NULL) {
 		vap->va_uid = proc->p_ucred->cr_ruid;
 		vap->va_gid = proc->p_ucred->cr_rgid;
 	} else {
 		vap->va_uid = 0;
 		vap->va_gid = 0;
 	}
 
 	if (pn->pn_attr != NULL)
 		error = pn_attr(curthread, proc, pn, vap);
 
 	if(proc != NULL)
 		PROC_UNLOCK(proc);
 
 	PFS_RETURN (error);
 }
 
 /*
  * Perform an ioctl
  */
 static int
 pfs_ioctl(struct vop_ioctl_args *va)
 {
 	struct vnode *vn;
 	struct pfs_vdata *pvd;
 	struct pfs_node *pn;
 	struct proc *proc;
 	int error;
 
 	vn = va->a_vp;
 	vn_lock(vn, LK_SHARED | LK_RETRY);
 	if (vn->v_iflag & VI_DOOMED) {
 		VOP_UNLOCK(vn, 0);
 		return (EBADF);
 	}
 	pvd = vn->v_data;
 	pn = pvd->pvd_pn;
 
 	PFS_TRACE(("%s: %lx", pn->pn_name, va->a_command));
 	pfs_assert_not_owned(pn);
 
 	if (vn->v_type != VREG) {
 		VOP_UNLOCK(vn, 0);
 		PFS_RETURN (EINVAL);
 	}
 	KASSERT_PN_IS_FILE(pn);
 
 	if (pn->pn_ioctl == NULL) {
 		VOP_UNLOCK(vn, 0);
 		PFS_RETURN (ENOTTY);
 	}
 
 	/*
 	 * This is necessary because process' privileges may
 	 * have changed since the open() call.
 	 */
 	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc)) {
 		VOP_UNLOCK(vn, 0);
 		PFS_RETURN (EIO);
 	}
 
 	error = pn_ioctl(curthread, proc, pn, va->a_command, va->a_data);
 
 	if (proc != NULL)
 		PROC_UNLOCK(proc);
 
 	VOP_UNLOCK(vn, 0);
 	PFS_RETURN (error);
 }
 
 /*
  * Perform getextattr
  */
 static int
 pfs_getextattr(struct vop_getextattr_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 	struct proc *proc;
 	int error;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	/*
 	 * This is necessary because either process' privileges may
 	 * have changed since the open() call.
 	 */
 	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
 		PFS_RETURN (EIO);
 
 	if (pn->pn_getextattr == NULL)
 		error = EOPNOTSUPP;
 	else
 		error = pn_getextattr(curthread, proc, pn,
 		    va->a_attrnamespace, va->a_name, va->a_uio,
 		    va->a_size, va->a_cred);
 
 	if (proc != NULL)
 		PROC_UNLOCK(proc);
 
 	PFS_RETURN (error);
 }
 
 /*
  * Convert a vnode to its component name
  */
 static int
 pfs_vptocnp(struct vop_vptocnp_args *ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct vnode **dvp = ap->a_vpp;
 	struct pfs_vdata *pvd = vp->v_data;
 	struct pfs_node *pd = pvd->pvd_pn;
 	struct pfs_node *pn;
 	struct mount *mp;
 	char *buf = ap->a_buf;
 	int *buflen = ap->a_buflen;
 	char pidbuf[PFS_NAMELEN];
 	pid_t pid = pvd->pvd_pid;
 	int len, i, error, locked;
 
 	i = *buflen;
 	error = 0;
 
 	pfs_lock(pd);
 
 	if (vp->v_type == VDIR && pd->pn_type == pfstype_root) {
 		*dvp = vp;
 		vhold(*dvp);
 		pfs_unlock(pd);
 		PFS_RETURN (0);
 	} else if (vp->v_type == VDIR && pd->pn_type == pfstype_procdir) {
 		len = snprintf(pidbuf, sizeof(pidbuf), "%d", pid);
 		i -= len;
 		if (i < 0) {
 			error = ENOMEM;
 			goto failed;
 		}
 		bcopy(pidbuf, buf + i, len);
 	} else {
 		len = strlen(pd->pn_name);
 		i -= len;
 		if (i < 0) {
 			error = ENOMEM;
 			goto failed;
 		}
 		bcopy(pd->pn_name, buf + i, len);
 	}
 
 	pn = pd->pn_parent;
 	pfs_unlock(pd);
 
 	mp = vp->v_mount;
 	error = vfs_busy(mp, 0);
 	if (error)
 		return (error);
 
 	/*
 	 * vp is held by caller.
 	 */
 	locked = VOP_ISLOCKED(vp);
 	VOP_UNLOCK(vp, 0);
 
 	error = pfs_vncache_alloc(mp, dvp, pn, pid);
 	if (error) {
 		vn_lock(vp, locked | LK_RETRY);
 		vfs_unbusy(mp);
 		PFS_RETURN(error);
 	}
 
 	*buflen = i;
 	VOP_UNLOCK(*dvp, 0);
 	vn_lock(vp, locked | LK_RETRY);
 	vfs_unbusy(mp);
 
 	PFS_RETURN (0);
 failed:
 	pfs_unlock(pd);
 	PFS_RETURN(error);
 }
 
 /*
  * Look up a file or directory
  */
 static int
 pfs_lookup(struct vop_cachedlookup_args *va)
 {
 	struct vnode *vn = va->a_dvp;
 	struct vnode **vpp = va->a_vpp;
 	struct componentname *cnp = va->a_cnp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pd = pvd->pvd_pn;
 	struct pfs_node *pn, *pdn = NULL;
 	struct mount *mp;
 	pid_t pid = pvd->pvd_pid;
 	char *pname;
 	int error, i, namelen, visible;
 
 	PFS_TRACE(("%.*s", (int)cnp->cn_namelen, cnp->cn_nameptr));
 	pfs_assert_not_owned(pd);
 
 	if (vn->v_type != VDIR)
 		PFS_RETURN (ENOTDIR);
 	KASSERT_PN_IS_DIR(pd);
 
 	error = VOP_ACCESS(vn, VEXEC, cnp->cn_cred, cnp->cn_thread);
 	if (error)
 		PFS_RETURN (error);
 
 	/*
 	 * Don't support DELETE or RENAME.  CREATE is supported so
 	 * that O_CREAT will work, but the lookup will still fail if
 	 * the file does not exist.
 	 */
 	if ((cnp->cn_flags & ISLASTCN) &&
 	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
 		PFS_RETURN (EOPNOTSUPP);
 
 	/* shortcut: check if the name is too long */
 	if (cnp->cn_namelen >= PFS_NAMELEN)
 		PFS_RETURN (ENOENT);
 
 	/* check that parent directory is visible... */
 	if (!pfs_visible(curthread, pd, pvd->pvd_pid, NULL))
 		PFS_RETURN (ENOENT);
 
 	/* self */
 	namelen = cnp->cn_namelen;
 	pname = cnp->cn_nameptr;
 	if (namelen == 1 && pname[0] == '.') {
 		pn = pd;
 		*vpp = vn;
 		VREF(vn);
 		PFS_RETURN (0);
 	}
 
 	mp = vn->v_mount;
 
 	/* parent */
 	if (cnp->cn_flags & ISDOTDOT) {
 		if (pd->pn_type == pfstype_root)
 			PFS_RETURN (EIO);
 		error = vfs_busy(mp, MBF_NOWAIT);
 		if (error != 0) {
 			vfs_ref(mp);
 			VOP_UNLOCK(vn, 0);
 			error = vfs_busy(mp, 0);
 			vn_lock(vn, LK_EXCLUSIVE | LK_RETRY);
 			vfs_rel(mp);
 			if (error != 0)
 				PFS_RETURN(ENOENT);
 			if (vn->v_iflag & VI_DOOMED) {
 				vfs_unbusy(mp);
 				PFS_RETURN(ENOENT);
 			}
 		}
 		VOP_UNLOCK(vn, 0);
 		KASSERT(pd->pn_parent != NULL,
 		    ("%s(): non-root directory has no parent", __func__));
 		/*
 		 * This one is tricky.  Descendents of procdir nodes
 		 * inherit their parent's process affinity, but
 		 * there's no easy reverse mapping.  For simplicity,
 		 * we assume that if this node is a procdir, its
 		 * parent isn't (which is correct as long as
 		 * descendents of procdir nodes are never procdir
 		 * nodes themselves)
 		 */
 		if (pd->pn_type == pfstype_procdir)
 			pid = NO_PID;
 		pfs_lock(pd);
 		pn = pd->pn_parent;
 		pfs_unlock(pd);
 		goto got_pnode;
 	}
 
 	pfs_lock(pd);
 
 	/* named node */
 	for (pn = pd->pn_nodes; pn != NULL; pn = pn->pn_next)
 		if (pn->pn_type == pfstype_procdir)
 			pdn = pn;
 		else if (pn->pn_name[namelen] == '\0' &&
 		    bcmp(pname, pn->pn_name, namelen) == 0) {
 			pfs_unlock(pd);
 			goto got_pnode;
 		}
 
 	/* process dependent node */
 	if ((pn = pdn) != NULL) {
 		pid = 0;
 		for (pid = 0, i = 0; i < namelen && isdigit(pname[i]); ++i)
 			if ((pid = pid * 10 + pname[i] - '0') > PID_MAX)
 				break;
 		if (i == cnp->cn_namelen) {
 			pfs_unlock(pd);
 			goto got_pnode;
 		}
 	}
 
 	pfs_unlock(pd);
 
 	PFS_RETURN (ENOENT);
 
  got_pnode:
 	pfs_assert_not_owned(pd);
 	pfs_assert_not_owned(pn);
 	visible = pfs_visible(curthread, pn, pid, NULL);
 	if (!visible) {
 		error = ENOENT;
 		goto failed;
 	}
 
 	error = pfs_vncache_alloc(mp, vpp, pn, pid);
 	if (error)
 		goto failed;
 
 	if (cnp->cn_flags & ISDOTDOT) {
 		vfs_unbusy(mp);
 		vn_lock(vn, LK_EXCLUSIVE | LK_RETRY);
 		if (vn->v_iflag & VI_DOOMED) {
 			vput(*vpp);
 			*vpp = NULL;
 			PFS_RETURN(ENOENT);
 		}
 	}
 	if (cnp->cn_flags & MAKEENTRY && !(vn->v_iflag & VI_DOOMED))
 		cache_enter(vn, *vpp, cnp);
 	PFS_RETURN (0);
  failed:
 	if (cnp->cn_flags & ISDOTDOT) {
 		vfs_unbusy(mp);
 		vn_lock(vn, LK_EXCLUSIVE | LK_RETRY);
 		*vpp = NULL;
 	}
 	PFS_RETURN(error);
 }
 
 /*
  * Open a file or directory.
  */
 static int
 pfs_open(struct vop_open_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 	int mode = va->a_mode;
 
 	PFS_TRACE(("%s (mode 0x%x)", pn->pn_name, mode));
 	pfs_assert_not_owned(pn);
 
 	/* check if the requested mode is permitted */
 	if (((mode & FREAD) && !(mode & PFS_RD)) ||
 	    ((mode & FWRITE) && !(mode & PFS_WR)))
 		PFS_RETURN (EPERM);
 
 	/* we don't support locking */
 	if ((mode & O_SHLOCK) || (mode & O_EXLOCK))
 		PFS_RETURN (EOPNOTSUPP);
 
 	PFS_RETURN (0);
 }
 
 /*
  * Read from a file
  */
 static int
 pfs_read(struct vop_read_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 	struct uio *uio = va->a_uio;
 	struct proc *proc;
 	struct sbuf *sb = NULL;
 	int error, locked;
 	off_t buflen;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	if (vn->v_type != VREG)
 		PFS_RETURN (EINVAL);
 	KASSERT_PN_IS_FILE(pn);
 
 	if (!(pn->pn_flags & PFS_RD))
 		PFS_RETURN (EBADF);
 
 	if (pn->pn_fill == NULL)
 		PFS_RETURN (EIO);
 
 	/*
 	 * This is necessary because either process' privileges may
 	 * have changed since the open() call.
 	 */
 	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
 		PFS_RETURN (EIO);
 	if (proc != NULL) {
 		_PHOLD(proc);
 		PROC_UNLOCK(proc);
 	}
 
 	vhold(vn);
 	locked = VOP_ISLOCKED(vn);
 	VOP_UNLOCK(vn, 0);
 
 	if (pn->pn_flags & PFS_RAWRD) {
 		PFS_TRACE(("%zd resid", uio->uio_resid));
 		error = pn_fill(curthread, proc, pn, NULL, uio);
 		PFS_TRACE(("%zd resid", uio->uio_resid));
 		goto ret;
 	}
 
 	if (uio->uio_resid < 0 || uio->uio_offset < 0 ||
 	    uio->uio_resid > OFF_MAX - uio->uio_offset) {
 		error = EINVAL;
 		goto ret;
 	}
 	buflen = uio->uio_offset + uio->uio_resid;
 	if (buflen > MAXPHYS)
 		buflen = MAXPHYS;
 
 	sb = sbuf_new(sb, NULL, buflen + 1, 0);
 	if (sb == NULL) {
 		error = EIO;
 		goto ret;
 	}
 
 	error = pn_fill(curthread, proc, pn, sb, uio);
 
 	if (error) {
 		sbuf_delete(sb);
 		goto ret;
 	}
 
 	/*
 	 * XXX: If the buffer overflowed, sbuf_len() will not return
 	 * the data length. Then just use the full length because an
 	 * overflowed sbuf must be full.
 	 */
 	if (sbuf_finish(sb) == 0)
 		buflen = sbuf_len(sb);
 	error = uiomove_frombuf(sbuf_data(sb), buflen, uio);
 	sbuf_delete(sb);
 ret:
 	vn_lock(vn, locked | LK_RETRY);
 	vdrop(vn);
 	if (proc != NULL)
 		PRELE(proc);
 	PFS_RETURN (error);
 }
 
 /*
  * Iterate through directory entries
  */
 static int
 pfs_iterate(struct thread *td, struct proc *proc, struct pfs_node *pd,
 	    struct pfs_node **pn, struct proc **p)
 {
 	int visible;
 
 	sx_assert(&allproc_lock, SX_SLOCKED);
 	pfs_assert_owned(pd);
  again:
 	if (*pn == NULL) {
 		/* first node */
 		*pn = pd->pn_nodes;
 	} else if ((*pn)->pn_type != pfstype_procdir) {
 		/* next node */
 		*pn = (*pn)->pn_next;
 	}
 	if (*pn != NULL && (*pn)->pn_type == pfstype_procdir) {
 		/* next process */
 		if (*p == NULL)
 			*p = LIST_FIRST(&allproc);
 		else
 			*p = LIST_NEXT(*p, p_list);
 		/* out of processes: next node */
 		if (*p == NULL)
 			*pn = (*pn)->pn_next;
 		else
 			PROC_LOCK(*p);
 	}
 
 	if ((*pn) == NULL)
 		return (-1);
 
 	if (*p != NULL) {
 		visible = pfs_visible_proc(td, *pn, *p);
 		PROC_UNLOCK(*p);
 	} else if (proc != NULL) {
 		visible = pfs_visible_proc(td, *pn, proc);
 	} else {
 		visible = 1;
 	}
 	if (!visible)
 		goto again;
 
 	return (0);
 }
 
 /* Directory entry list */
 struct pfsentry {
 	STAILQ_ENTRY(pfsentry)	link;
 	struct dirent		entry;
 };
 STAILQ_HEAD(pfsdirentlist, pfsentry);
 
 /*
  * Return directory entries.
  */
 static int
 pfs_readdir(struct vop_readdir_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pd = pvd->pvd_pn;
 	pid_t pid = pvd->pvd_pid;
 	struct proc *p, *proc;
 	struct pfs_node *pn;
 	struct uio *uio;
 	struct pfsentry *pfsent, *pfsent2;
 	struct pfsdirentlist lst;
 	off_t offset;
 	int error, i, resid;
 
 	STAILQ_INIT(&lst);
 	error = 0;
 	KASSERT(pd->pn_info == vn->v_mount->mnt_data,
 	    ("%s(): pn_info does not match mountpoint", __func__));
 	PFS_TRACE(("%s pid %lu", pd->pn_name, (unsigned long)pid));
 	pfs_assert_not_owned(pd);
 
 	if (vn->v_type != VDIR)
 		PFS_RETURN (ENOTDIR);
 	KASSERT_PN_IS_DIR(pd);
 	uio = va->a_uio;
 
 	/* only allow reading entire entries */
 	offset = uio->uio_offset;
 	resid = uio->uio_resid;
 	if (offset < 0 || offset % PFS_DELEN != 0 ||
 	    (resid && resid < PFS_DELEN))
 		PFS_RETURN (EINVAL);
 	if (resid == 0)
 		PFS_RETURN (0);
 
+	if (!pfs_lookup_proc(pid, &proc))
+		PFS_RETURN (ENOENT);
+
 	sx_slock(&allproc_lock);
 	pfs_lock(pd);
+	PROC_LOCK(proc);
 
         /* check if the directory is visible to the caller */
-        if (!pfs_visible(curthread, pd, pid, &proc)) {
+        if (!pfs_visible_proc(curthread, pd, proc)) {
+		_PRELE(proc);
+		PROC_UNLOCK(proc);
 		sx_sunlock(&allproc_lock);
 		pfs_unlock(pd);
                 PFS_RETURN (ENOENT);
 	}
 	KASSERT(pid == NO_PID || proc != NULL,
 	    ("%s(): no process for pid %lu", __func__, (unsigned long)pid));
 
 	/* skip unwanted entries */
 	for (pn = NULL, p = NULL; offset > 0; offset -= PFS_DELEN) {
 		if (pfs_iterate(curthread, proc, pd, &pn, &p) == -1) {
 			/* nothing left... */
-			if (proc != NULL)
+			if (proc != NULL) {
+				_PRELE(proc);
 				PROC_UNLOCK(proc);
+			}
 			pfs_unlock(pd);
 			sx_sunlock(&allproc_lock);
 			PFS_RETURN (0);
 		}
 	}
 
 	/* fill in entries */
 	while (pfs_iterate(curthread, proc, pd, &pn, &p) != -1 &&
 	    resid >= PFS_DELEN) {
 		if ((pfsent = malloc(sizeof(struct pfsentry), M_IOV,
 		    M_NOWAIT | M_ZERO)) == NULL) {
 			error = ENOMEM;
 			break;
 		}
 		pfsent->entry.d_reclen = PFS_DELEN;
 		pfsent->entry.d_fileno = pn_fileno(pn, pid);
 		/* PFS_DELEN was picked to fit PFS_NAMLEN */
 		for (i = 0; i < PFS_NAMELEN - 1 && pn->pn_name[i] != '\0'; ++i)
 			pfsent->entry.d_name[i] = pn->pn_name[i];
 		pfsent->entry.d_namlen = i;
 		/* NOTE: d_off is the offset of the *next* entry. */
 		pfsent->entry.d_off = offset + PFS_DELEN;
 		switch (pn->pn_type) {
 		case pfstype_procdir:
 			KASSERT(p != NULL,
 			    ("reached procdir node with p == NULL"));
 			pfsent->entry.d_namlen = snprintf(pfsent->entry.d_name,
 			    PFS_NAMELEN, "%d", p->p_pid);
 			/* fall through */
 		case pfstype_root:
 		case pfstype_dir:
 		case pfstype_this:
 		case pfstype_parent:
 			pfsent->entry.d_type = DT_DIR;
 			break;
 		case pfstype_file:
 			pfsent->entry.d_type = DT_REG;
 			break;
 		case pfstype_symlink:
 			pfsent->entry.d_type = DT_LNK;
 			break;
 		default:
 			panic("%s has unexpected node type: %d", pn->pn_name, pn->pn_type);
 		}
 		PFS_TRACE(("%s", pfsent->entry.d_name));
 		dirent_terminate(&pfsent->entry);
 		STAILQ_INSERT_TAIL(&lst, pfsent, link);
 		offset += PFS_DELEN;
 		resid -= PFS_DELEN;
 	}
-	if (proc != NULL)
+	if (proc != NULL) {
+		_PRELE(proc);
 		PROC_UNLOCK(proc);
+	}
 	pfs_unlock(pd);
 	sx_sunlock(&allproc_lock);
 	i = 0;
 	STAILQ_FOREACH_SAFE(pfsent, &lst, link, pfsent2) {
 		if (error == 0)
 			error = uiomove(&pfsent->entry, PFS_DELEN, uio);
 		free(pfsent, M_IOV);
 		i++;
 	}
 	PFS_TRACE(("%ju bytes", (uintmax_t)(i * PFS_DELEN)));
 	PFS_RETURN (error);
 }
 
 /*
  * Read a symbolic link
  */
 static int
 pfs_readlink(struct vop_readlink_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 	struct uio *uio = va->a_uio;
 	struct proc *proc = NULL;
 	char buf[PATH_MAX];
 	struct sbuf sb;
 	int error, locked;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	if (vn->v_type != VLNK)
 		PFS_RETURN (EINVAL);
 	KASSERT_PN_IS_LINK(pn);
 
 	if (pn->pn_fill == NULL)
 		PFS_RETURN (EIO);
 
 	if (pvd->pvd_pid != NO_PID) {
 		if ((proc = pfind(pvd->pvd_pid)) == NULL)
 			PFS_RETURN (EIO);
 		if (proc->p_flag & P_WEXIT) {
 			PROC_UNLOCK(proc);
 			PFS_RETURN (EIO);
 		}
 		_PHOLD(proc);
 		PROC_UNLOCK(proc);
 	}
 	vhold(vn);
 	locked = VOP_ISLOCKED(vn);
 	VOP_UNLOCK(vn, 0);
 
 	/* sbuf_new() can't fail with a static buffer */
 	sbuf_new(&sb, buf, sizeof buf, 0);
 
 	error = pn_fill(curthread, proc, pn, &sb, NULL);
 
 	if (proc != NULL)
 		PRELE(proc);
 	vn_lock(vn, locked | LK_RETRY);
 	vdrop(vn);
 
 	if (error) {
 		sbuf_delete(&sb);
 		PFS_RETURN (error);
 	}
 
 	if (sbuf_finish(&sb) != 0) {
 		sbuf_delete(&sb);
 		PFS_RETURN (ENAMETOOLONG);
 	}
 
 	error = uiomove_frombuf(sbuf_data(&sb), sbuf_len(&sb), uio);
 	sbuf_delete(&sb);
 	PFS_RETURN (error);
 }
 
 /*
  * Reclaim a vnode
  */
 static int
 pfs_reclaim(struct vop_reclaim_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	return (pfs_vncache_free(va->a_vp));
 }
 
 /*
  * Set attributes
  */
 static int
 pfs_setattr(struct vop_setattr_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	/* Silently ignore unchangeable attributes. */
 	PFS_RETURN (0);
 }
 
 /*
  * Write to a file
  */
 static int
 pfs_write(struct vop_write_args *va)
 {
 	struct vnode *vn = va->a_vp;
 	struct pfs_vdata *pvd = vn->v_data;
 	struct pfs_node *pn = pvd->pvd_pn;
 	struct uio *uio = va->a_uio;
 	struct proc *proc;
 	struct sbuf sb;
 	int error;
 
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
 	if (vn->v_type != VREG)
 		PFS_RETURN (EINVAL);
 	KASSERT_PN_IS_FILE(pn);
 
 	if (!(pn->pn_flags & PFS_WR))
 		PFS_RETURN (EBADF);
 
 	if (pn->pn_fill == NULL)
 		PFS_RETURN (EIO);
 
 	/*
 	 * This is necessary because either process' privileges may
 	 * have changed since the open() call.
 	 */
 	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
 		PFS_RETURN (EIO);
 	if (proc != NULL) {
 		_PHOLD(proc);
 		PROC_UNLOCK(proc);
 	}
 
 	if (pn->pn_flags & PFS_RAWWR) {
 		error = pn_fill(curthread, proc, pn, NULL, uio);
 		if (proc != NULL)
 			PRELE(proc);
 		PFS_RETURN (error);
 	}
 
 	sbuf_uionew(&sb, uio, &error);
 	if (error) {
 		if (proc != NULL)
 			PRELE(proc);
 		PFS_RETURN (error);
 	}
 
 	error = pn_fill(curthread, proc, pn, &sb, uio);
 
 	sbuf_delete(&sb);
 	if (proc != NULL)
 		PRELE(proc);
 	PFS_RETURN (error);
 }
 
 /*
  * Vnode operations
  */
 struct vop_vector pfs_vnodeops = {
 	.vop_default =		&default_vnodeops,
 
 	.vop_access =		pfs_access,
 	.vop_cachedlookup =	pfs_lookup,
 	.vop_close =		pfs_close,
 	.vop_create =		VOP_EOPNOTSUPP,
 	.vop_getattr =		pfs_getattr,
 	.vop_getextattr =	pfs_getextattr,
 	.vop_ioctl =		pfs_ioctl,
 	.vop_link =		VOP_EOPNOTSUPP,
 	.vop_lookup =		vfs_cache_lookup,
 	.vop_mkdir =		VOP_EOPNOTSUPP,
 	.vop_mknod =		VOP_EOPNOTSUPP,
 	.vop_open =		pfs_open,
 	.vop_read =		pfs_read,
 	.vop_readdir =		pfs_readdir,
 	.vop_readlink =		pfs_readlink,
 	.vop_reclaim =		pfs_reclaim,
 	.vop_remove =		VOP_EOPNOTSUPP,
 	.vop_rename =		VOP_EOPNOTSUPP,
 	.vop_rmdir =		VOP_EOPNOTSUPP,
 	.vop_setattr =		pfs_setattr,
 	.vop_symlink =		VOP_EOPNOTSUPP,
 	.vop_vptocnp =		pfs_vptocnp,
 	.vop_write =		pfs_write,
 	/* XXX I've probably forgotten a few that need VOP_EOPNOTSUPP */
 };