4 files changed, 48 insertions, 21 deletions

diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index 22dfe01ac624..c9bc2074d5e6 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -3736,8 +3736,8 @@ cache_fpl_terminated(struct cache_fpl *fpl)
 
 #define CACHE_FPL_SUPPORTED_CN_FLAGS \
 	(NC_NOMAKEENTRY | NC_KEEPPOSENTRY | LOCKLEAF | LOCKPARENT | WANTPARENT | \
-	 FOLLOW | LOCKSHARED | SAVENAME | SAVESTART | WILLBEDIR | ISOPEN | \
-	 NOMACCHECK | AUDITVNODE1 | AUDITVNODE2 | NOCAPCHECK)
+	 FAILIFEXISTS | FOLLOW | LOCKSHARED | SAVENAME | SAVESTART | WILLBEDIR | \
+	 ISOPEN | NOMACCHECK | AUDITVNODE1 | AUDITVNODE2 | NOCAPCHECK)
 
 #define CACHE_FPL_INTERNAL_CN_FLAGS \
 	(ISDOTDOT | MAKEENTRY | ISLASTCN)
@@ -3990,6 +3990,11 @@ cache_fplookup_final_modifying(struct cache_fpl *fpl)
 		return (cache_fpl_handled(fpl, EROFS));
 	}
 
+	if (fpl->tvp != NULL && (cnp->cn_flags & FAILIFEXISTS) != 0) {
+		cache_fpl_smr_exit(fpl);
+		return (cache_fpl_handled(fpl, EEXIST));
+	}
+
 	/*
 	 * Secure access to dvp; check cache_fplookup_partial_setup for
 	 * reasoning.
@@ -4070,6 +4075,12 @@ cache_fplookup_final_modifying(struct cache_fpl *fpl)
 		return (cache_fpl_aborted(fpl));
 	}
 
+	if ((cnp->cn_flags & FAILIFEXISTS) != 0) {
+		vput(dvp);
+		vput(tvp);
+		return (cache_fpl_handled(fpl, EEXIST));
+	}
+
 	if ((cnp->cn_flags & LOCKLEAF) == 0) {
 		VOP_UNLOCK(tvp);
 	}
@@ -4221,6 +4232,7 @@ cache_fplookup_noentry(struct cache_fpl *fpl)
 	MPASS(!cache_fpl_isdotdot(cnp));
 
 	if (cnp->cn_nameiop != LOOKUP) {
+		fpl->tvp = NULL;
 		return (cache_fplookup_modifying(fpl));
 	}
 
diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
index 511efaa9d01a..da04dd09af40 100644
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -545,6 +545,16 @@ namei(struct nameidata *ndp)
 	ndp->ni_debugflags |= NAMEI_DBG_CALLED;
 	if (ndp->ni_startdir != NULL)
 		ndp->ni_debugflags |= NAMEI_DBG_HADSTARTDIR;
+	if (cnp->cn_flags & FAILIFEXISTS) {
+		KASSERT(cnp->cn_nameiop == CREATE,
+		    ("%s: FAILIFEXISTS passed for op %d", __func__, cnp->cn_nameiop));
+		/*
+		 * The limitation below is to restrict hairy corner cases.
+		 */
+		KASSERT((cnp->cn_flags & (LOCKPARENT | LOCKLEAF)) == LOCKPARENT,
+		    ("%s: FAILIFEXISTS must be passed with LOCKPARENT and without LOCKLEAF",
+		    __func__));
+	}
 	/*
 	 * For NDVALIDATE.
 	 *
@@ -1295,8 +1305,11 @@ success:
 			goto bad2;
 		}
 	}
-	if (ndp->ni_vp != NULL && ndp->ni_vp->v_type == VDIR)
+	if (ndp->ni_vp != NULL) {
 		nameicap_tracker_add(ndp, ndp->ni_vp);
+		if ((cnp->cn_flags & (FAILIFEXISTS | ISSYMLINK)) == FAILIFEXISTS)
+			goto bad_eexist;
+	}
 	return (0);
 
 bad2:
@@ -1311,6 +1324,24 @@ bad:
 		vput(dp);
 	ndp->ni_vp = NULL;
 	return (error);
+bad_eexist:
+	/*
+	 * FAILIFEXISTS handling.
+	 *
+	 * XXX namei called with LOCKPARENT but not LOCKLEAF has the strange
+	 * behaviour of leaving the vnode unlocked if the target is the same
+	 * vnode as the parent.
+	 */
+	MPASS((cnp->cn_flags & ISSYMLINK) == 0);
+	if (ndp->ni_vp == ndp->ni_dvp)
+		vrele(ndp->ni_dvp);
+	else
+		vput(ndp->ni_dvp);
+	vrele(ndp->ni_vp);
+	ndp->ni_dvp = NULL;
+	ndp->ni_vp = NULL;
+	NDFREE(ndp, NDF_ONLY_PNBUF);
+	return (EEXIST);
 }
 
 /*
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index cbfff229540a..5a30b06e4e9e 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -3768,7 +3768,6 @@ kern_mkdirat(struct thread *td, int fd, const char *path, enum uio_seg segflg,
     int mode)
 {
 	struct mount *mp;
-	struct vnode *vp;
 	struct vattr vattr;
 	struct nameidata nd;
 	int error;
@@ -3777,26 +3776,11 @@ kern_mkdirat(struct thread *td, int fd, const char *path, enum uio_seg segflg,
 restart:
 	bwillwrite();
 	NDINIT_ATRIGHTS(&nd, CREATE, LOCKPARENT | SAVENAME | AUDITVNODE1 |
-	    NC_NOMAKEENTRY | NC_KEEPPOSENTRY, segflg, path, fd,
+	    NC_NOMAKEENTRY | NC_KEEPPOSENTRY | FAILIFEXISTS, segflg, path, fd,
 	    &cap_mkdirat_rights, td);
 	nd.ni_cnd.cn_flags |= WILLBEDIR;
 	if ((error = namei(&nd)) != 0)
 		return (error);
-	vp = nd.ni_vp;
-	if (vp != NULL) {
-		NDFREE(&nd, NDF_ONLY_PNBUF);
-		/*
-		 * XXX namei called with LOCKPARENT but not LOCKLEAF has
-		 * the strange behaviour of leaving the vnode unlocked
-		 * if the target is the same vnode as the parent.
-		 */
-		if (vp == nd.ni_dvp)
-			vrele(nd.ni_dvp);
-		else
-			vput(nd.ni_dvp);
-		vrele(vp);
-		return (EEXIST);
-	}
 	if (vn_start_write(nd.ni_dvp, &mp, V_NOWAIT) != 0) {
 		NDFREE(&nd, NDF_ONLY_PNBUF);
 		vput(nd.ni_dvp);
diff --git a/sys/sys/namei.h b/sys/sys/namei.h
index dfb5e5e4cec3..ddba9cbd8912 100644
--- a/sys/sys/namei.h
+++ b/sys/sys/namei.h
@@ -143,7 +143,7 @@ int	cache_fplookup(struct nameidata *ndp, enum cache_fpl_status *status,
 #define	LOCKLEAF	0x0004	/* lock vnode on return */
 #define	LOCKPARENT	0x0008	/* want parent vnode returned locked */
 #define	WANTPARENT	0x0010	/* want parent vnode returned unlocked */
-/* UNUSED		0x0020 */
+#define	FAILIFEXISTS	0x0020	/* return EEXIST if found */
 #define	FOLLOW		0x0040	/* follow symbolic links */
 #define	BENEATH		0x0080	/* No escape from the start dir */
 #define	LOCKSHARED	0x0100	/* Shared lock leaf */