vfs: add NDFREE_NOTHING and convert several NDFREE_PNBUF callers

Check the comment above the routine for reasoning.

4 files changed, 47 insertions, 18 deletions

diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
index ad369fc7b23e..44e48bc864a3 100644
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -1568,7 +1568,7 @@ unp_connectat(int fd, struct socket *so, struct sockaddr *nam,
 	else
 		vp = nd.ni_vp;
 	ASSERT_VOP_LOCKED(vp, "unp_connect");
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	if (error)
 		goto bad;
 
diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
index da04dd09af40..3b8ee558e023 100644
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -1487,6 +1487,33 @@ NDFREE_PNBUF(struct nameidata *ndp)
 	}
 }
 
+/*
+ * NDFREE_PNBUF replacement for callers that know there is no buffer.
+ *
+ * This is a hack. Preferably the VFS layer would not produce anything more
+ * than it was asked to do. Unfortunately several non-LOOKUP cases can add the
+ * HASBUF flag to the result. Even then an interface could be implemented where
+ * the caller specifies what they expected to see in the result and what they
+ * are going to take care of.
+ *
+ * In the meantime provide this kludge as a trivial replacement for NDFREE_PNBUF
+ * calls scattered throughout the kernel where we know for a fact the flag must not
+ * be seen.
+ */
+#ifdef INVARIANTS
+void
+NDFREE_NOTHING(struct nameidata *ndp)
+{
+	struct componentname *cnp;
+
+	cnp = &ndp->ni_cnd;
+	KASSERT(cnp->cn_nameiop == LOOKUP, ("%s: got non-LOOKUP op %d\n",
+	    __func__, cnp->cn_nameiop));
+	KASSERT((cnp->cn_flags & (SAVENAME | HASBUF)) == 0,
+	    ("%s: bad flags \%" PRIx64 "\n", __func__, cnp->cn_flags));
+}
+#endif
+
 void
 (NDFREE)(struct nameidata *ndp, const u_int flags)
 {
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index ce5da109f168..560a003765d5 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -340,7 +340,7 @@ kern_statfs(struct thread *td, const char *path, enum uio_seg pathseg,
 		return (error);
 	mp = nd.ni_vp->v_mount;
 	vfs_ref(mp);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	vput(nd.ni_vp);
 	return (kern_do_statfs(td, mp, buf));
 }
@@ -949,11 +949,11 @@ kern_chdir(struct thread *td, const char *path, enum uio_seg pathseg)
 		return (error);
 	if ((error = change_dir(nd.ni_vp, td)) != 0) {
 		vput(nd.ni_vp);
-		NDFREE(&nd, NDF_ONLY_PNBUF);
+		NDFREE_NOTHING(&nd);
 		return (error);
 	}
 	VOP_UNLOCK(nd.ni_vp);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	pwd_chdir(td, nd.ni_vp);
 	return (0);
 }
@@ -991,12 +991,12 @@ sys_chroot(struct thread *td, struct chroot_args *uap)
 	VOP_UNLOCK(nd.ni_vp);
 	error = pwd_chroot(td, nd.ni_vp);
 	vrele(nd.ni_vp);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	return (error);
 e_vunlock:
 	vput(nd.ni_vp);
 error:
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	return (error);
 }
 
@@ -2118,7 +2118,7 @@ kern_accessat(struct thread *td, int fd, const char *path,
 	vp = nd.ni_vp;
 
 	error = vn_access(vp, amode, usecred, td);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	vput(vp);
 out:
 	if (usecred != cred) {
@@ -2417,7 +2417,7 @@ kern_statat(struct thread *td, int flag, int fd, const char *path,
 		if (__predict_false(hook != NULL))
 			hook(nd.ni_vp, sbp);
 	}
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	vput(nd.ni_vp);
 #ifdef __STAT_TIME_T_EXT
 	sbp->st_atim_ext = 0;
@@ -2557,7 +2557,7 @@ kern_pathconf(struct thread *td, const char *path, enum uio_seg pathseg,
 	    pathseg, path, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 
 	error = VOP_PATHCONF(nd.ni_vp, name, valuep);
 	vput(nd.ni_vp);
@@ -2613,7 +2613,7 @@ kern_readlinkat(struct thread *td, int fd, const char *path,
 
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	vp = nd.ni_vp;
 
 	error = kern_readlink_vp(vp, buf, bufseg, count, td);
@@ -2764,7 +2764,7 @@ kern_chflagsat(struct thread *td, int fd, const char *path,
 	    &cap_fchflags_rights, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	error = setfflags(td, nd.ni_vp, flags);
 	vrele(nd.ni_vp);
 	return (error);
@@ -2893,7 +2893,7 @@ kern_fchmodat(struct thread *td, int fd, const char *path,
 	    &cap_fchmod_rights, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	error = setfmode(td, td->td_ucred, nd.ni_vp, mode);
 	vrele(nd.ni_vp);
 	return (error);
@@ -3006,7 +3006,7 @@ kern_fchownat(struct thread *td, int fd, const char *path,
 
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	error = setfown(td, td->td_ucred, nd.ni_vp, uid, gid);
 	vrele(nd.ni_vp);
 	return (error);
@@ -3219,7 +3219,7 @@ kern_utimesat(struct thread *td, int fd, const char *path,
 
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	error = setutimes(td, nd.ni_vp, ts, 2, tptr == NULL);
 	vrele(nd.ni_vp);
 	return (error);
@@ -3255,7 +3255,7 @@ kern_lutimes(struct thread *td, const char *path, enum uio_seg pathseg,
 	NDINIT(&nd, LOOKUP, NOFOLLOW | AUDITVNODE1, pathseg, path, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	error = setutimes(td, nd.ni_vp, ts, 2, tptr == NULL);
 	vrele(nd.ni_vp);
 	return (error);
@@ -3370,7 +3370,7 @@ kern_utimensat(struct thread *td, int fd, const char *path,
 	 * "If both tv_nsec fields are UTIME_OMIT... EACCESS may be detected."
 	 * "Search permission is denied by a component of the path prefix."
 	 */
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	if ((flags & UTIMENS_EXIT) == 0)
 		error = setutimes(td, nd.ni_vp, ts, 2, flags & UTIMENS_NULL);
 	vrele(nd.ni_vp);
@@ -4226,7 +4226,7 @@ sys_revoke(struct thread *td, struct revoke_args *uap)
 	if ((error = namei(&nd)) != 0)
 		return (error);
 	vp = nd.ni_vp;
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	if (vp->v_type != VCHR || vp->v_rdev == NULL) {
 		error = EINVAL;
 		goto out;
@@ -4361,7 +4361,7 @@ kern_getfhat(struct thread *td, int flags, int fd, const char *path,
 	error = namei(&nd);
 	if (error != 0)
 		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
+	NDFREE_NOTHING(&nd);
 	vp = nd.ni_vp;
 	bzero(&fh, sizeof(fh));
 	fh.fh_fsid = vp->v_mount->mnt_stat.f_fsid;
diff --git a/sys/sys/namei.h b/sys/sys/namei.h
index ddba9cbd8912..c045bc7c6bc5 100644
--- a/sys/sys/namei.h
+++ b/sys/sys/namei.h
@@ -288,8 +288,10 @@ void NDFREE(struct nameidata *, const u_int);
 } while (0)
 
 #ifdef INVARIANTS
+void NDFREE_NOTHING(struct nameidata *);
 void NDVALIDATE(struct nameidata *);
 #else
+#define NDFREE_NOTHING(ndp)	do { } while (0)
 #define NDVALIDATE(ndp)	do { } while (0)
 #endif