Index: head/sys/fs/devfs/devfs_vnops.c
===================================================================
--- head/sys/fs/devfs/devfs_vnops.c
+++ head/sys/fs/devfs/devfs_vnops.c
@@ -1137,7 +1137,6 @@
 	int error, ref, vlocked;
 	struct cdevsw *dsw;
 	struct file *fpop;
-	struct mtx *mtxp;
 
 	if (vp->v_type == VBLK)
 		return (ENXIO);
@@ -1191,16 +1190,6 @@
 #endif
 	if (fp->f_ops == &badfileops)
 		finit(fp, fp->f_flag, DTYPE_VNODE, dev, &devfs_ops_f);
-	mtxp = mtx_pool_find(mtxpool_sleep, fp);
-
-	/*
-	 * Hint to the dofilewrite() to not force the buffer draining
-	 * on the writer to the file.  Most likely, the write would
-	 * not need normal buffers.
-	 */
-	mtx_lock(mtxp);
-	fp->f_vnread_flags |= FDEVFS_VNODE;
-	mtx_unlock(mtxp);
 	return (error);
 }
 
Index: head/sys/kern/sys_generic.c
===================================================================
--- head/sys/kern/sys_generic.c
+++ head/sys/kern/sys_generic.c
@@ -561,9 +561,6 @@
 		ktruio = cloneuio(auio);
 #endif
 	cnt = auio->uio_resid;
-	if (fp->f_type == DTYPE_VNODE &&
-	    (fp->f_vnread_flags & FDEVFS_VNODE) == 0)
-		bwillwrite();
 	if ((error = fo_write(fp, auio, td->td_ucred, flags, td))) {
 		if (auio->uio_resid != cnt && (error == ERESTART ||
 		    error == EINTR || error == EWOULDBLOCK))
Index: head/sys/sys/file.h
===================================================================
--- head/sys/sys/file.h
+++ head/sys/sys/file.h
@@ -208,7 +208,6 @@
 
 #define	FOFFSET_LOCKED       0x1
 #define	FOFFSET_LOCK_WAITING 0x2
-#define	FDEVFS_VNODE	     0x4
 
 #endif /* _KERNEL || _WANT_FILE */