FSF_WANT
if (fs->fs_flags & FSF_WANT)
fs->fs_flags &= ~FSF_WANT;
if (fs->fs_flags & FSF_WANT)
if (fs->fs_flags & FSF_WANT)
if (oflags != fs->fs_flags && (fs->fs_flags & FSF_WANT))
if (error < 0 && wchan && !(fs->fs_flags & FSF_WANT)) {
fs->fs_flags |= FSF_WANT;