=== PATCHED dirfs_vnops.o compile (errors identical to unpatched = pre-existing) ===
*** Error code 1
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1057:10: error: implicit declaration of function 'kmalloc'; did you mean 'falloc'? [-Werror=implicit-function-declaration]
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1057:10: error: nested extern declaration of 'kmalloc' [-Werror=nested-externs]
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1057:44: error: 'M_ZERO' undeclared (first use in this function); did you mean 'NZERO'?
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1057:53: error: 'M_WAITOK' undeclared (first use in this function); did you mean 'F_WAIT'?
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1078:3: error: implicit declaration of function 'kfree'; did you mean 'crfree'? [-Werror=implicit-function-declaration]
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1078:3: error: nested extern declaration of 'kfree' [-Werror=nested-externs]
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1186:43: error: 'M_ZERO' undeclared (first use in this function); did you mean 'NZERO'?
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1186:52: error: 'M_WAITOK' undeclared (first use in this function); did you mean 'F_WAIT'?
/usr/src/sys/vfs/dirfs/dirfs_vnops.c:1250:38: error: 'M_WAITOK' undeclared (first use in this function); did you mean 'F_WAIT'?

=== sibling dirfs_vfsops.o BUILT CLEAN in full vkernel build ===
-rw-r--r--  1 root  1000  190704 Jul  6 13:48 dirfs_vfsops.o

=== fix applied to /usr/src ===
	buf = kmalloc(uio->uio_resid + 1, M_DIRFS_MISC, M_WAITOK | M_ZERO);
		error = uiomove(buf, nlen, uio);