diff --git a/sys/cam/ctl/ctl_backend_block.c b/sys/cam/ctl/ctl_backend_block.c
index c56023bf787..8ea52aa323d 100644
--- a/sys/cam/ctl/ctl_backend_block.c
+++ b/sys/cam/ctl/ctl_backend_block.c
@@ -2123,18 +2123,7 @@ ctl_be_block_open(struct ctl_be_block_softc *softc,
 		return (1);
 	}
 
-	if (!curthread->td_proc->p_fd->fd_cdir) {
-		curthread->td_proc->p_fd->fd_cdir = rootvnode;
-		VREF(rootvnode);
-	}
-	if (!curthread->td_proc->p_fd->fd_rdir) {
-		curthread->td_proc->p_fd->fd_rdir = rootvnode;
-		VREF(rootvnode);
-	}
-	if (!curthread->td_proc->p_fd->fd_jdir) {
-		curthread->td_proc->p_fd->fd_jdir = rootvnode;
-		VREF(rootvnode);
-	}
+	pwd_ensure_dirs();
 
  again:
 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, be_lun->dev_path, curthread);
diff --git a/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c b/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
index 9ff798a15b7..52d695b4f5a 100644
--- a/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
+++ b/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
@@ -67,21 +67,10 @@ static void *
 kobj_open_file_vnode(const char *file)
 {
 	struct thread *td = curthread;
-	struct filedesc *fd;
 	struct nameidata nd;
 	int error, flags;
 
-	fd = td->td_proc->p_fd;
-	FILEDESC_XLOCK(fd);
-	if (fd->fd_rdir == NULL) {
-		fd->fd_rdir = rootvnode;
-		vref(fd->fd_rdir);
-	}
-	if (fd->fd_cdir == NULL) {
-		fd->fd_cdir = rootvnode;
-		vref(fd->fd_cdir);
-	}
-	FILEDESC_XUNLOCK(fd);
+	pwd_ensure_dirs();
 
 	flags = FREAD | O_NOFOLLOW;
 	NDINIT(&nd, LOOKUP, 0, UIO_SYSSPACE, file, td);
diff --git a/sys/cddl/compat/opensolaris/sys/vnode.h b/sys/cddl/compat/opensolaris/sys/vnode.h
index 22256cf1f1e..d7bc7f7a1b2 100644
--- a/sys/cddl/compat/opensolaris/sys/vnode.h
+++ b/sys/cddl/compat/opensolaris/sys/vnode.h
@@ -162,7 +162,6 @@ vn_openat(char *pnamep, enum uio_seg seg, int filemode, int createmode,
     int fd)
 {
 	struct thread *td = curthread;
-	struct filedesc *fdc;
 	struct nameidata nd;
 	int error, operation;
 
@@ -179,17 +178,7 @@ vn_openat(char *pnamep, enum uio_seg seg, int filemode, int createmode,
 	}
 	ASSERT(umask == 0);
 
-	fdc = td->td_proc->p_fd;
-	FILEDESC_XLOCK(fdc);
-	if (fdc->fd_rdir == NULL) {
-		fdc->fd_rdir = rootvnode;
-		vref(fdc->fd_rdir);
-	}
-	if (fdc->fd_cdir == NULL) {
-		fdc->fd_cdir = rootvnode;
-		vref(fdc->fd_rdir);
-	}
-	FILEDESC_XUNLOCK(fdc);
+	pwd_ensure_dirs();
 
 	if (startvp != NULL)
 		vref(startvp);
diff --git a/sys/compat/ndis/subr_ndis.c b/sys/compat/ndis/subr_ndis.c
index f3ba7008411..ac26a2e093f 100644
--- a/sys/compat/ndis/subr_ndis.c
+++ b/sys/compat/ndis/subr_ndis.c
@@ -2817,10 +2817,7 @@ NdisOpenFile(status, filehandle, filelength, filename, highestaddr)
 
 	/* Some threads don't have a current working directory. */
 
-	if (td->td_proc->p_fd->fd_rdir == NULL)
-		td->td_proc->p_fd->fd_rdir = rootvnode;
-	if (td->td_proc->p_fd->fd_cdir == NULL)
-		td->td_proc->p_fd->fd_cdir = rootvnode;
+	pwd_ensure_dirs();
 
 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, path, td);
 
diff --git a/sys/dev/xen/blkback/blkback.c b/sys/dev/xen/blkback/blkback.c
index 459271ea26f..f266ffd2902 100644
--- a/sys/dev/xen/blkback/blkback.c
+++ b/sys/dev/xen/blkback/blkback.c
@@ -2692,18 +2692,7 @@ xbb_open_backend(struct xbb_softc *xbb)
 	if ((xbb->flags & XBBF_READ_ONLY) == 0)
 		flags |= FWRITE;
 
-	if (!curthread->td_proc->p_fd->fd_cdir) {
-		curthread->td_proc->p_fd->fd_cdir = rootvnode;
-		VREF(rootvnode);
-	}
-	if (!curthread->td_proc->p_fd->fd_rdir) {
-		curthread->td_proc->p_fd->fd_rdir = rootvnode;
-		VREF(rootvnode);
-	}
-	if (!curthread->td_proc->p_fd->fd_jdir) {
-		curthread->td_proc->p_fd->fd_jdir = rootvnode;
-		VREF(rootvnode);
-	}
+	pwd_ensure_dirs();
 
  again:
 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, xbb->dev_name, curthread);
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 7e54d1835a4..4229cc9ece4 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -68,6 +68,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sbuf.h>
 #include <sys/signalvar.h>
 #include <sys/socketvar.h>
+#include <sys/kdb.h>
 #include <sys/stat.h>
 #include <sys/sx.h>
 #include <sys/syscallsubr.h>
@@ -308,6 +309,24 @@ fdfree(struct filedesc *fdp, int fd)
 #endif
 }
 
+void
+pwd_ensure_dirs(void)
+{
+	struct filedesc *fdp;
+
+	fdp = curproc->p_fd;
+	FILEDESC_XLOCK(fdp);
+	if (fdp->fd_cdir == NULL) {
+		fdp->fd_cdir = rootvnode;
+		VREF(rootvnode);
+	}
+	if (fdp->fd_rdir == NULL) {
+		fdp->fd_rdir = rootvnode;
+		VREF(rootvnode);
+	}
+	FILEDESC_XUNLOCK(fdp);
+}
+
 /*
  * System calls on descriptors.
  */
diff --git a/sys/kern/subr_firmware.c b/sys/kern/subr_firmware.c
index 20ab76e282b..172d7198dc6 100644
--- a/sys/kern/subr_firmware.c
+++ b/sys/kern/subr_firmware.c
@@ -383,19 +383,8 @@ firmware_put(const struct firmware *p, int flags)
 static void
 set_rootvnode(void *arg, int npending)
 {
-	struct thread *td = curthread;
-	struct proc *p = td->td_proc;
 
-	FILEDESC_XLOCK(p->p_fd);
-	if (p->p_fd->fd_cdir == NULL) {
-		p->p_fd->fd_cdir = rootvnode;
-		VREF(rootvnode);
-	}
-	if (p->p_fd->fd_rdir == NULL) {
-		p->p_fd->fd_rdir = rootvnode;
-		VREF(rootvnode);
-	}
-	FILEDESC_XUNLOCK(p->p_fd);
+	pwd_ensure_dirs();
 
 	free(arg, M_TEMP);
 }
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
index e569a3b5e0e..727a09827f1 100644
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -208,6 +208,7 @@ fd_modified(struct filedesc *fdp, int fd, seq_t seq)
 /* cdir/rdir/jdir manipulation functions. */
 void	pwd_chdir(struct thread *td, struct vnode *vp);
 int	pwd_chroot(struct thread *td, struct vnode *vp);
+void	pwd_ensure_dirs(void);
 
 #endif /* _KERNEL */