diff --git a/sys/fs/ext2fs/ext2_vfsops.c b/sys/fs/ext2fs/ext2_vfsops.c
index b82a41e41163..e72b07d423ba 100644
--- a/sys/fs/ext2fs/ext2_vfsops.c
+++ b/sys/fs/ext2fs/ext2_vfsops.c
@@ -675,7 +675,8 @@ ext2_mountfs(struct vnode *devvp, struct mount *mp)
 	 * Initialize filesystem stat information in mount struct.
 	 */
 	MNT_ILOCK(mp);
-	mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED;
+	mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED |
+	    MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 	return (0);
 out:
diff --git a/sys/fs/fuse/fuse_vfsops.c b/sys/fs/fuse/fuse_vfsops.c
index c00a96cb10f6..0a3337303d9f 100644
--- a/sys/fs/fuse/fuse_vfsops.c
+++ b/sys/fs/fuse/fuse_vfsops.c
@@ -337,6 +337,7 @@ fuse_vfsop_mount(struct mount *mp)
 	MNT_ILOCK(mp);
 	mp->mnt_data = data;
 	mp->mnt_flag |= MNT_LOCAL;
+	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 	/* We need this here as this slot is used by getnewvnode() */
 	mp->mnt_stat.f_iosize = PAGE_SIZE;
diff --git a/sys/fs/msdosfs/msdosfs_vfsops.c b/sys/fs/msdosfs/msdosfs_vfsops.c
index 11659349357b..7c6d3ed08d5f 100644
--- a/sys/fs/msdosfs/msdosfs_vfsops.c
+++ b/sys/fs/msdosfs/msdosfs_vfsops.c
@@ -759,6 +759,7 @@ mountmsdosfs(struct vnode *devvp, struct mount *mp)
 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
 	MNT_ILOCK(mp);
 	mp->mnt_flag |= MNT_LOCAL;
+	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 
 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
diff --git a/sys/fs/nandfs/nandfs_vfsops.c b/sys/fs/nandfs/nandfs_vfsops.c
index eb07d4f5e988..7132635efdca 100644
--- a/sys/fs/nandfs/nandfs_vfsops.c
+++ b/sys/fs/nandfs/nandfs_vfsops.c
@@ -1391,6 +1391,7 @@ nandfs_mountfs(struct vnode *devvp, struct mount *mp)
 	nmp->nm_ronly = ronly;
 	MNT_ILOCK(mp);
 	mp->mnt_flag |= MNT_LOCAL;
+	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 	nmp->nm_nandfsdev = nandfsdev;
 	/* Add our mountpoint */
diff --git a/sys/fs/nfsclient/nfs_clvfsops.c b/sys/fs/nfsclient/nfs_clvfsops.c
index 9758b4c3a0a0..43ca6dc1683d 100644
--- a/sys/fs/nfsclient/nfs_clvfsops.c
+++ b/sys/fs/nfsclient/nfs_clvfsops.c
@@ -1198,7 +1198,8 @@ nfs_mount(struct mount *mp)
 out:
 	if (!error) {
 		MNT_ILOCK(mp);
-		mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_NO_IOPF;
+		mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_NO_IOPF |
+		    MNTK_USES_BCACHE;
 		MNT_IUNLOCK(mp);
 	}
 	return (error);
diff --git a/sys/fs/nfsserver/nfs_nfsdport.c b/sys/fs/nfsserver/nfs_nfsdport.c
index 0ea48cdc8562..5e450284b30e 100644
--- a/sys/fs/nfsserver/nfs_nfsdport.c
+++ b/sys/fs/nfsserver/nfs_nfsdport.c
@@ -1270,8 +1270,11 @@ nfsvno_fsync(struct vnode *vp, u_int64_t off, int cnt, struct ucred *cred,
 	 * file is done.  At this time VOP_FSYNC does not accept offset and
 	 * byte count parameters so call VOP_FSYNC the whole file for now.
 	 * The same is true for NFSv4: RFC 3530 Sec. 14.2.3.
+	 * File systems that do not use the buffer cache (as indicated
+	 * by MNTK_USES_BCACHE not being set) must use VOP_FSYNC().
 	 */
-	if (cnt == 0 || cnt > MAX_COMMIT_COUNT) {
+	if (cnt == 0 || cnt > MAX_COMMIT_COUNT ||
+	    (vp->v_mount->mnt_kern_flag & MNTK_USES_BCACHE) == 0) {
 		/*
 		 * Give up and do the whole thing
 		 */
diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c
index fd3d385a6142..618090b70a81 100644
--- a/sys/fs/nullfs/null_vfsops.c
+++ b/sys/fs/nullfs/null_vfsops.c
@@ -199,7 +199,7 @@ nullfs_mount(struct mount *mp)
 	}
 	mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT;
 	mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
-	    MNTK_SUSPENDABLE;
+	    (MNTK_SUSPENDABLE | MNTK_USES_BCACHE);
 	MNT_IUNLOCK(mp);
 	mp->mnt_data = xmp;
 	vfs_getnewfsid(mp);
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index fda80c96faf4..8e34456621ca 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -3147,6 +3147,7 @@ DB_SHOW_COMMAND(mount, db_show_mount)
 	MNT_KERN_FLAG(MNTK_VGONE_WAITER);
 	MNT_KERN_FLAG(MNTK_LOOKUP_EXCL_DOTDOT);
 	MNT_KERN_FLAG(MNTK_MARKER);
+	MNT_KERN_FLAG(MNTK_USES_BCACHE);
 	MNT_KERN_FLAG(MNTK_NOASYNC);
 	MNT_KERN_FLAG(MNTK_UNMOUNT);
 	MNT_KERN_FLAG(MNTK_MWAIT);
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index 6fb2d08187b7..b1678457fa7e 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -355,6 +355,7 @@ void          __mnt_vnode_markerfree_active(struct vnode **mvp, struct mount *);
 #define	MNTK_LOOKUP_EXCL_DOTDOT	0x00000800
 #define	MNTK_MARKER		0x00001000
 #define	MNTK_UNMAPPED_BUFS	0x00002000
+#define	MNTK_USES_BCACHE	0x00004000 /* FS uses the buffer cache. */
 #define MNTK_NOASYNC	0x00800000	/* disable async */
 #define MNTK_UNMOUNT	0x01000000	/* unmount in progress */
 #define	MNTK_MWAIT	0x02000000	/* waiting for unmount to finish */
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index 6e2e55692251..88f952f0cd4e 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -1055,7 +1055,8 @@ ffs_mountfs(devvp, mp, td)
 	 */
 	MNT_ILOCK(mp);
 	mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED |
-	    MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS | MNTK_SUSPENDABLE;
+	    MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS | MNTK_SUSPENDABLE |
+	    MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 #ifdef UFS_EXTATTR
 #ifdef UFS_EXTATTR_AUTOSTART