VB_WRITE
if (!vfs_busy(mp, VB_WRITE|VB_WAIT)) {
error = vfs_busy(mp, VB_WRITE|VB_WAIT|VB_DUPOK);
if (vfs_busy(mp, VB_WRITE|VB_NOWAIT))
int rwflags = ISSET(flags, VB_WRITE) ? RW_WRITE : RW_READ;
if (vfs_busy(mp, VB_WRITE|VB_WAIT))
error = vfs_busy(mp, VB_WRITE|VB_WAIT|VB_DUPOK);
if (vfs_busy(mp, VB_WRITE|VB_NOWAIT) ||